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The Origins of Consciousness

              (103285 bytes)Consciousness is something we have, but how do we get it?  And does any other species have it?  Could non-organic machines have it?  



These questions are, essentially, questions concerning the development of consciousness, and psychology offers two, perhaps three, principal views of development:


The Phylogenetic View

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In the 17th century, the question of animal consciousness was foreclosed by Descartes' strict dualistic separation of mind and body, which entailed a strict separation between humans (who have minds and free will) and animals (which just have bodies, and operate as reflex machines).  Descartes, following Catholic doctrine (he was aware of what had happened to "heretics" such as Girodano Bruno and Galileo) identified humans as the highest stage of development, except of course for God and the angels.  But the doctrine of human free will legitimized such concepts of sin, and crime -- actions for which individuals can be held accountable.  But in Descartes' view, animals had nothing like consciousness or free will.  They operated solely by reflex -- a word that Descartes coined to refer to his theory that energy from the stimulus was reflected back into the environment in the form of behavior.  In any event, Descartes held that "lower" animals simply did not have the sorts of conscious experiences that were crucial to Descartes's "Cogito" insight.  For example, he asserted that they did not feel pain -- the yelp of a dog which is being beaten is simply a reflex.

              (105663 bytes)In 007Phrenology.jpg (105017 bytes) some respects, the Cartesian viewpoint is exemplified by Pierre Flourens (1794-1867), a French neuroanatomist, who characterized the decorticate pigeon as a reflex machine.  Flourens agreed with the phrenologists Gall and Spurzheim that the brain was the organ of the mind, but he argued against their tendencies toward radical localizationism.  Rather, he sided with those who argued instead for cortical equipotentiality.  


While the phrenologists had attempted to relate mind to body by examining the lumps and depressions of the skull, Flourens pioneered the method of surgical ablation -- destroying parts of the brain, and then observing the behavioral consequences. 

With his ablation method, Flourens identified the medulla oblongata as a motor center, and established that the cerebellum played an important role in maintaining stability and coordinating motor activities.  When it came to the cortex, he agreed that some "lower" sensory and motor functions were differentiated and localized.  At the same time, he argued that the "higher" functions of perception, volition, and intellect were distributed throughout the cerebral cortex.  For Flourens and other proponents of equipotentiality, the brain -- the cerebral cortex, anyway -- was the organ of a unified mind.

In his famous experiments on reflexes in the decorticate pigeon, for example, Flourens (1824, 1842) found that a number of "reflex" behaviors were preserved:

At the same time, other behaviors were abolished:
From these observations, Flourens concluded that the decorticate pigeon was, indeed, a reflex machine that merely reacts to external stimulation, but does not engage in any spontaneous or self-initiated behavior.


Localization and Equipotentiality

The debate between localization and equipotentiality continued to rage throughout the rest of the 19th century, and into the 20th.  Research by Broca and Wernicke identified areas of the cerebral cortex that were crucial for language and speech, but outside of the sensory and motor projection areas, the cerebral cortex was largely held to consist of undifferentiated "association cortex".  In 1929, Karl Lashley announced his Law of Mass Action, based on experiments with rats in mazes that were not all that different from the ablation experiments pioneered by Flourens a century earlier.  

The Law of Mass Action was the triumph of the equipotentialists.  More recently, however, modern behavioral and cognitive neuroscience has embraced a doctrine of modularity that holds that various mental and behavioral functions are performed by specialized cognitive modules or systems, which in turn are associated with dedicated brain modules or systems.  Studies of implicit memory in amnesia and of implicit perception in blindsight, for example, have been interpreted as suggesting that there are separate modules for conscious and unconscious memory, perception, and the like.  It has even been suggested (by D.L. Schacter, who has since revised his thinking) that conscious awareness in general is mediated by a conscious awareness system which takes inputs from modules responsible for perception, memory, and other functions.  If the outputs of these processing modules reach the CAS, we are aware of them; if they do not, we perform these functions unconsciously.  


Evolution and Comparative Psychology

                (95355 bytes)Descartes had argued for a strict separation of man from "lower" animals.  But  Darwin's Origin of Species by Natural Selection (1859) changed all that, by arguing convincingly for a continuity between humans and other (sic), nonhuman, animals.  In Darwin's theory of evolution by natural selection, adaptations that confer reproductive advantages are passed down to one's offspring, eventuating in the creation of new species.  Thus, the theory held, different species are descended from common ancestors.  

Darwin's doctrine of evolution was spelled out most clearly with respect to the morphological similarities and differences between species -- physical traits.  But at the same time, the theory implied that evolution applied to mental similarities and differences as well.

By the same token, even rabid Darwinists, seemed to acknowledge the possibility of discontinuity.  You will recall from the lectures on Mind and Body, the assertion of epiphenomenalism by T.H. Huxley, Darwin's cousin and "bulldog" defender of evolution.  Note, however, that Huxley refers only to "the consciousness of brutes" (emphasis added) -- which seems to leave open the possibility that the consciousness of men (and women) wasn't epiphenomenal.  If Huxley meant to imply that human consciousness was not epiphenomenal, this would count as a qualitative discontinuity between humans and other, nonhuman animals.

Evolution had been much discussed before Darwin came along -- what was really new in Darwin's theory was the idea of natural selection as the means by which evolution occurred.  In fact, Darwin's cousin, Herbert Spencer, had already argued in his Principles of Psychology (1855) that the processes of mind were continuous with the processes of life, and that an evolution of mind could be traced in parallel with the evolution of life.  Spencer argued that the mind evolved through a series of stages:

Darwin himself embraced this view in Descent of Man (1871):

There can be no doubt that the difference between the mind of the lowest man and that of the highest animal is immense.  Nevertheless, the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind.  We have seen that the senses and intuitions, the various emotions and faculties, such as love, memory, attention, curiosity, imitation, reason, etc. of which man boasts, may be found in an incipient, or even sometimes in a well-developed condition, in the lower animals....

If it could be proved that certain high mental powers, such as the formation of general concepts, self-consciousness, etc., were absolutely peculiar to man, which seems extremely doubtful, it is not improbable that these qualities are merely the incidental results of other highly-advanced intellectual faculties; and these again mainly the result of the continued use of a perfect language....

That such evolution is at least possible, ought not to be denied, for we daily see these faculties developing in every infant; and we may trace a perfect gradation from the mind of an utter idiot, lower than that of an animal low in the scale, to the mind of a Newton.

The evolutionary perspective (the "modern synthesis") which defines modern biology was quickly imported into psychology, with assertions of continuity at the level of mind and behavior, not just anatomy and physiology.  In recent history, what began as E.O. Wilson's Sociobiology has itself evolved into the contemporary field of evolutionary psychology.

Interestingly, the stage for this importation was set by Darwin himself, who argued in the Descent of Man (1871) and The Expression of Emotions in Man and Animals (1872) that there were similarities between humans and other animals in their facial and other bodily expressions of emotions.

013BasicEmotions.jpg (86020 bytes)In contemporary psychology, Darwin's position has been embraced most vigorously by Paul Ekman, in his work on innate "basic emotions" such as happiness, sadness, fear, anger, surprise, and disgust.  



Animal Consciousness and the Rise of Comparative Psychology

                (99492 bytes)In the 19th century, Darwin's position was embraced within psychology by his friend George John Romanes (1848-1894), whose Animal Intelligence (1882) attempted to marshal the evidence for intelligence and consciousness in nonhuman animals, especially dogs, horses, and primates.  Romanes' method was essentially to collect anecdotes that, to him, illustrated these traits in animal behavior -- for example, a dog bringing its food dish to its master when it wanted to be fed, or what seemed to be a coordinated attack on humans by a band of baboons.  To quote Romanes at length:

One day, watching a small column of these ants (Eciton hamata), I placed a little stone on one of them to secure it.  The next that approached, as soon as it discovered its situation, ran backwards in an agitated manner, and soon communicated the intelligence to the others.  They rushed to the rescue; some bit at the stone and tried to move it, others seized the prisoner by the legs and tugged with such force that I thought the legs would be pulled off, but they persevered until they got the captive free.  I next covered one up with a piece of clay, leaving only the ends of its antennae projecting.  It was soon discovered by its fellows, which set to work immediately, and by biting off pieces of the clay soon liberated it.  Another time I found a very few of them passing along at intervals.  I confined one of these under a piece of clay at a little distance from the line, with his head projecting.  Several ants passed it, but at least one discovered it and tried to pull it out, but could not.  It immediately set off at a great rate, and I thought it had deserted its comrade, but it had only gone for assistance, for in a short time about a dozen ants came hurrying up, evidently fully informed of the circumstances of the case, for they made directly for their imprisoned comrade and soon set him free.  I do not see how this action could be distinctive.  It was sympathetic help, such as man only among the higher mammalia shows.  The excitement and ardour with which they carried on their unflagging exertions for the rescue of their comrade could not have been greater if they had been human beings.

This observation seems unequivocal as proving fellow-feeling and sympathy, so far as we can trace any analogy between the emotions of the higher animals and those of insects.

By means of such anecdotes, Romanes accumulated evidence for "higher" mental functions, including memory, emotion, and intelligence, in nonhuman animals. Stories such as those Romanes collected have a powerful hold on our imagination.  In our time, similar collections of anecdotes have appeared from time to time -- as in Jeffrey Masson's When Elephants Weep (1996), which claimed that many animal species have complex emotional lives.

In Mental Evolution in Animals (1883) Romanes distinguished between reflexes and instincts fixed by heredity, and intelligence which involved learning and consciousness.  As evidence of the evolution of mental abilities, he gathered evidence of memory in sea urchins, learning in mollusks, tool use in monkeys, and conscience in dogs and apes.  

In Mental Evolution in Man (1888), Romanes distinguished among three categories of mental phenomena:

Like Darwin and Spencer, Romanes argued that it was "improbable" that the body was continuous, but mind discontinuous:

"[There is a] very strong prima facie case in favour of the view that there has been no interruption of the developmental process in the course of psychological history; but that the mind of man, like the mind of animals... has evolved."

Romanes is considered to be the founder of the field of comparative psychology, but it is important to understand that there were serious problems with his methodology:

Still, Romanes played an important role in bringing evolutionary thinking to bear on the question of animal intelligence and consciousness.  He argued that it was "improbable that the body was continuous, but the mind discontinuous".  

                (101654 bytes)Romanes' point about continuity was well taken, but his methods were criticized by another English psychologist, C. Lloyd Morgan (1852-1936) -- who in fact had been Romanes' student!  Morgan complained that Romanes leaped to the hypothesis of animal intelligence, while overlooking the simpler hypothesis that apparently intelligent animal behavior had its origins in instincts and trial-and-error learning.  Ever since, the field of comparative psychology has been dominated by Morgan's "canon":

Always interpret behavior in terms of the lowest psychological process that could produce it.  

Nevertheless, Morgan elaborated on Romanes' distinctions among reflex, instinct, and intelligence:

027Washburn.jpg (118877 bytes)If Romanes was perhaps too liberal in attributing consciousness to nonhuman animals, perhaps Morgan was too conservative.  A sort of "third way" into the problem was offered by Margaret Floy Washburn (1871-1939), who was the first female PhD in psychology (from Cornell, under Titchener, in 1894) and the second woman to serve as president of the American Psychological Association (the first was Mary Whiton Calkins, who invented paired-associate learning).  In The Animal Mind (1903), Washburn argued that the question of animal consciousness was really no different than the familiar and ancient philosophical problem of other minds. 


"The mind of each human being forms a region inaccessible to all save its possessor....  If my neighbor's mind is a mystery to me, how great is the mystery which looks out of the eyes of a dog, and how insoluble the problem presented by the mind of... an ant or a spider?"

Still, Washburn noted, on the reasonable assumption that all human minds are "built on the same pattern", we make inferences about others' mental states from their words and actions.  And the same holds for animal's mental states:

"[A]ll psychic interpretation of animal behavior must be on the analogy of human experience...  Our acquaintance with the mind of animals rests upon the same basis as our acquaintance with the mind of our fellow-man: both are derived by inference from observed behavior."

Washburn found a number of traditional criteria for animal consciousness unsatisfactory, because they could all occur unconsciously:

In the end, Washburn settled on a dual criterion for animal consciousness:

"We know not where consciousness begins in the animal world.  We know where it surely exists -- in ourselves; we know where it exists beyond a reasonable doubt -- in those animals of structure resembling ours which readily adapt themselves to the lessons of experience. Beyond this point, for all we know, it may exist in simpler and simpler forms until we reach the very lowest of living beings."

Consciousness in Plants?

Much the same kind of anecdotal evidence has also been deployed to make the argument that plants, as well as animals, are conscious.  The idea that plants might be conscious has its origins in The Secret Life of Plants, by Peter Tompkins and Christopher Byrd, which found its way to the New York Times best-seller list in 1973.  Although that book was mostly a piece of pseudoscience, more recently some serious plant biologists have argued that plants can show behavior that, if displayed by animals, would be taken as evidence of intelligence and consciousness -- even though plants lack anything remotely resembling a nervous system.  In a "manifesto" for "plant neurobiology", Eric Brenner and his colleagues point out that plants respond to changes in their environment, and possess signalling systems that resemble the electrical and chemical activity of an animal's nervous system (Trends in Plant Science, 2006, 11:413-419).  These authors, and like-minded individuals, founded the Society for Plant Neurobiology in 2005, along with its flagship journal, Plant Signalling & Behavior

Not surprisingly, this development has been opposed by a large number of other plant scientists, who see this new research as a kind of throwback to the bad old days of TSLOP.  See, for example, "Plant neurobiology: no brain, no gain?" by A. Alpi et al., Trends in Plant Science, 2007;12:135-136.

The proponents argue that plant "behavior" goes beyond mere photo- and hydrotropisms.  It sometimes really looks like plants are responding flexibly to changed environmental circumstances (which is one definition of intelligence), responding to injuries (like being cut or harvested), and communicating their internal physiological states to other plants. 

The evidence is largely anecdotal, but the question of "plant neurobiology" is really, no different from the one raised by Romanes and Washburn: We know that we ourselves are conscious, and we can infer that other humans are conscious, but how would we know whether another kind of creature is conscious?  Romanes and Washburn asked this question about apes, dogs, and ants. But think about the question of consciousness in computers:  computers don't have the same physiology as we do, but that doesn't prevent serious people from asking whether computers could be conscious, and how we could know. And the same question crops up in the search for extraterrestrial intelligence how would we know whether a non-carbon-based life form is conscious?

The question of consciousness in plants is no different from the question of consciousness in nonhuman animals, machines, and alien lifeforms.  It can't be rejected out of hand -- by saying, for example, that something that doesn't have a human-like nervous system can't be conscious.  Rather, it forces us to be clear about what we mean by consciousness, so that we could develop convincing tests for it.

For an overview of the argument about mind, behavior, and consciousness in plants, see "The Intelligent Plant" by Michael Pollan, New Yorker, 12/23-30/2013.

Intelligence, Learning, and the Behaviorist Revolution

For Morgan, the essential question of the evolution of mind was:

How is congenital variation [i.e., in instincts] related to acquired modification [i.e., learning]?

Of course, this is an old question.  Jean Baptiste Lamarck (1744-1829), a French naturalist, had proposed that acquired habits were passed on to the organism's offspring through heredity -- a doctrine which became known as the inheritance of acquired characteristics.  As Lamarck put it:

 [C]ongenital variation will gradually render hereditary... that [which] was provisionally attained by plastic modification."

Darwin and his followers, including Romanes and Morgan, were adamantly opposed to the Lamarckian doctrine.  For them, behavior was passed from generation to generation by means of "organic selection".  In response to a sudden environmental change, certain acquired habits might have favored adaptation to the new environment; but what is inherited by the next generation was only a congenital variation favoring the acquired modification, rather than the modification itself.  What the last generation learned, cannot be inherited by the next generation -- the next generation has to learn it anew.

022Thorndike.jpg (88961 bytes)For better or for worse, it turned out that Morgan's evidence was also anecdotal, and so it fell to Edward L. Thorndike (1874-1949) to bring the study of animal intelligence into the laboratory.  Working at roughly the same time as Pavlov, Thorndike's classic studies of instrumental conditioning (e.g., cats in "puzzle boxes") led to the formulation of a set of "connectionist" (his term) laws of stimulus-response learning: 


In Animal Intelligence (1898), Thorndike had defined intelligence as the ability to form new associations -- but the associations in question were between stimuli and responses, not between two ideas, or between ideas and actions.  For Thorndike, human rational thought was merely an extension of associative learning.  In the 1911 revision of his book, Thorndike actually redefined psychology as a science of behavior -- and this two years before John B. Watson initiated the behaviorist revolution in psychology!  For Thorndike, intelligence, reasoning, and consciousness played no role in animal behavior, and this position inevitably raised the question of whether they played any role in human behavior either. 


The Continuity Conundrum

Romanes, Morgan, and Thorndike represent three responses to the Darwinian doctrine of psychological continuity.

025Watson.jpg (86829 bytes)And if Thorndike didn't do so in so many words, Watson and Skinner were certainly prepared to.  In fact, Washburn's 1903 book on The Animal Mind was the direct target of Watson's twin manifestos, "Psychology as a Behaviorist Views  It" (1913) and Psychology from the Standpoint of a Behaviorist (1919).




Insight, Purpose, and Curiosity in Animal Behavior

030CatTrigonometry.jpg (144641 bytes) Beginning with J.B. Watson, and culminating in the work of B.F. Skinner, the radical behaviorists turned the continuity assumption on its head. Whereas Romanes wanted to attributed consciousness and intelligence to nonhuman animals, the behaviorists wanted to deny it (or at least its functional importance) to humans as well.  



Despite the hegemony of behaviorist thought in the period 1920-1950 or so, interest in animal consciousness and intelligence persisted -- just as interest in human consciousness persisted in those who studied the span of apprehension and Gestalt perception.  

031Kohler.jpg (117148 bytes)Among the most famous examples of consciousness in animals were Wolfgang Kohler's experiments on insight learning in chimpanzees, as described in The Mentality of Apes (1977).  At the time that World War I broke out, Kohler (1887-1967) was working at a primate research facility operated by the Prussian Academy of Sciences in the Canary Islands.  The war essentially marooned him off the Atlantic coast of Africa, and with lots of time on his hands -- leading to the studies that made him famous.  


032Chimpanzees.jpg (73024 bytes)In his experiments, Kohler constructed a kind of playground, with a scattering of objects.  Then he would present the chimpanzees with a problem of obtaining food that was not directly accessible to them - -for example, a bunch of bananas lying outside the enclosure, or hung out of reach.  In order to solve these problems, the chimps would have to use their playthings as tools.

While solving these problems, Kohler believed that the chimpanzees engaged in "cognitive trial and error":

From Kohler's point of view, the animals were "experimenting in their minds" before using tools -- engaging in conscious insight and planning.  

Of course, there are a number of problems with this inference, including:

034Tolman.jpg (102909 bytes)Animal consciousness was also implied in Edward C. Tolman's classic studies of latent learning in rats, performed at UC Berkeley in the 1930s (Tolman Hall is named after him).  In his experiments, Tolman allowed rats to explore a maze without reward.  Compared to animals who were rewarded for reaching the goal box, they seemed not to learn anything at all.  But when reward was introduced into the goal box, the previously unrewarded animals immediately began to traverse the correct path from the start box to the goal box more quickly -- just as quickly, in fact, as those who had been continuously rewarded.  


While Thorndike's Law of Effect had asserted that reinforcement is necessary for learning to occur, Tolman concluded that animals acquire knowledge simply through experience, without need of reward or punishment.  In the mazes, for example, they acquired a "cognitive map" of the territory.  Later, they could then use this knowledge for their own purposes, as circumstances warranted -- for example, quickly finding their way to the goal box once they learned that there was food to be eaten there.

In fact, although the behaviorists argued that reinforcement shaped behavior that began as random, E.R. Hilgard went so far as to argue that the even the animal's response on the very first trial of learning is not random.  Rather, Hilgard argued, it has the character of a hypothesis -- it is as if the animal thinks to itself, "I wonder what will happen if I turn left?".

Of course, the radical behaviorists did not take kindly to this kind of mentalizing, and they sometimes caricatured Tolman's rats as "lost in thought at the choice point".  

036Harlow.jpg (109432 bytes)Caricatures aside, Tolman had it right about the role of reward in learning, and it became increasingly obvious that animal behavior wasn't motivated solely by rewards and punishments, but rather by goals of prediction and control.  For example, at Wisconsin Harry F. Harlow (1950a, 1959b), he of the famous studies of monkey love (which came later), performed classic studies of curiosity and intrinsic motivation.  In his research, Harlow presented rhesus monkeys with wooden puzzle blocks.  In one condition, the animals were rewarded with food for making correct moves; in the control condition there was no reward.  In general, there were no differences in performance between the two conditions.  And contrary to Thorndike's Law of Effect, hunger actually interfered with performance (when the monkeys were not hungry, but received food as a reward, they stored it for later).  Harlow concluded that the monkeys were intrinsically motivated to solve the puzzles -- they did so even without promise or prospect of reward.  The study was one of a number of early studies of learning and reinforcement that, like Tolman's work, undermined the behaviorist Law of Effect.  But in the present context, Harlow's findings suggests that the monkeys were curious about the puzzles. 

Harlow was fond of telling the story of one evening when he left his laboratory at 600 N. Park Street (and sometimes known as Goon Park), on the edge of the University of Wisconsin Campus, he was startled to look back and see the lights flashing on and off.  Fearing that there was a short-circuit that could cause a fire, he returned to find one of his rhesus monkeys flipping the light on and off -- apparently just for the sheer enjoyment of it.  Another example of intrinsic motivation.


Consciousness in Cognitive Ethology

Interest in human consciousness was revived by the cognitive revolution of the 1950s and 1960s, with its renewed interest in mental states and processes; and by virtue of the continuity assumption, the question was once again raised whether the behavior of nonhuman animals was mediated by conscious mental states, and intelligent processes, as that of humans was (or seemed to be).

The late Donald B. Griffin, of Rockefeller University, argued in the affirmative in a series of books: The Question of Animal Awareness (1976), Animal Thinking (1984), and Animal Minds (1992).  

Griffin asked "What is it about some kinds of behavior that leads us to feel that it is accompanied by conscious thinking?"  As criteria for consciousness, Griffin rejected mere complexity, or adaptability to changing circumstances, and based his arguments for animal awareness on three considerations:

A good example of Griffin's method is provided by his analysis of the assassin bug (from Animal Thinking, 1984):

[The bug has] camouflaged itself chemically and tactile by gluing bits of a termite nest all over its body. In this way it is able to capture a termite at the opening of the nest without alarming the soldier termites.  After sucking out the termite’s semifluid organs, the assassin bug jiggles the empty exoskeleton in front of the next opening in order to attract another termite worker….  When a second termite seizes the first, it is then captured and consumed itself…. [T]he process may be repeated continuously many times by the same assassin bug.  The extraordinary complexity and coordination of these actions strongly suggest conscious thought, even though the assassin bug’s central nervous system is very small.

Griffin is considered to be the founder of the field of cognitive ethology.  Classical ethology, as exemplified by the Nobel-Prize-winning work of Konrad Lorenz, Nikko Tinbergen, and Karl Frisch, was interested in the evolution of behavior -- imprinting in ducks, the zig-zag mating dance of the stickleback, and dancing in honeybees.  Cognitive ethology is interested in the evolution of mental processes.  (The term was later appropriated by the philosopher Daniel Dennett for somewhat different purposes.)

However, Griffin's behaviorist critics (e.g., Blumberg & Wasserman, 1995, 1996) accused him of making a behavioral analog to the creationists' argument from design -- that behavior is so complex that only consciousness and intelligence could produce it.  They drew an analogy to arguments against evolution by proponents of creationism or "intelligent design" -- who assert, in much the same way, that nature is so complex that it could not have arisen by chance, but must have been designed by God.  Thus, in their view, Mind occupies the same place in Griffin's cognitive ethology as God does in creationism (this was, of course, a particularly nasty argument to make against a biologist who accepts in the theory of evolution!).  Instead of a "mentalistic comparative psychology", Blumberg and Wasserman argue for "animal mindlessness" -- and just so their intentions are clear, they assert that human consciousness is epiphenomenal as well:

"[T]he mentalistic approach in vogue today is as useless for understanding human behavior as it is for understanding animal behavior.

040Honeybee.jpg (139020 bytes)Still, many ethologists, like Gould and Gould (e.g., The Animal Mind, 1994), find it compelling to attribute mental states to nonhuman animals.  For example, they find evidence of consciousness even in the behavior of invertebrates like honeybees:

For example, in discussing the dance "language" by which honeybees communicate the location of a pollen source, Gould and Gould write:

"This vibrating pollen forager is reporting a food source about 15 degrees to the right of the sun’s direction. Six attending bees are also being told of the distance to the food and the dancer’s opinion of its quality."

Still, it must be recognized that the cognitive ethology of Griffin and the Goulds was still essentially anecdotal.  To be sure, they had more systematic data than was available to Romanes, but their analysis still relied on an interpretation that was easy to contest.  What was needed was a clear demonstration of animal consciousness, which quickly came in two forms.



DarwinMonkeyMirror.jpg (132513 bytes)The first was the mirror test of self-awareness developed by Gordon Gallup (1970), based on observations originally made by Darwin (1871, 1872) himself.  When a mirror was placed outside the cage of some orangutans residing in the London Zoo, Darwin observed three stages of response:

053Darwin.jpg (102039 bytes)But what is really going on? Are they reacting to the image as if it were another ape -- first treating it as a threat, and later as benign?  Or do they realize, eventually, that they are looking at themselves?  


Inspired by Darwin's test, Gordon Gallup embarked on a study of mirror self-recognition in chimpanzees which has become a classic in consciousness research.

055GallupMirror.jpg (58251 bytes)When Gallup (1970) repeated Darwin's test, he found that the initial response of chimpanzees (and other animals) to exposure to a mirror is to explore the mirror and engage in other-directed behaviors -- i.e., to treat their reflection as if it were another animal.  With continued exposure, however, chimps begin to engage in self-directed behaviors, using the mirror to explore themselves -- especially hidden parts of their bodies:

Gallup concluded that the chimps were now reacting to the image as if it were a representation of themselves.  Put another way, eventually the chimps actually came to recognize themselves in the mirror. 

In a formal test of self-awareness, Gallup painted red marks on the foreheads of mirror-habituated chimpanzees. 057GallupSelf.jpg (39844 bytes) The painting was performed while the chimps were anesthetized and the paint was odorless, so the animals could only notice the spot when they looked at themselves in the mirror. The chimps' response was to examine the spots visually -- by looking at themselves in the mirror, touching the spots, and visually inspecting (and smelling) the fingers that had touched the spots. Gallup argued that the chimpanzees recognized a discrepancy between their self-image and their image in the mirror.

By comparison, a study by Nielsen and Dissanayake (2004) showed that all human infants show mirror self-recognition by 24 months of age.


img059.jpg (70347 bytes)Later primate experiments by Daniel Povinelli added methodological niceties, such as a comparison of marked and unmarked facial regions. 




062MirrorCont.jpg (94207 bytes)Another Povinelli study indicated 061SelfMirror.jpg (50744 bytes)that mirror self-recognition is relatively rare, even among chimpanzees.  It happens, but it's rare. 




Thus, not all chimpanzees show self-recognition in mirrors.  In general, the effect is obtained from chimps who are sexually mature (but not too old), have been raised in groups, and have had prior mirror exposure.  In the photo at right, a group of chimpanzees confront their reflections in the windows of a farmhouse in western Uganda.  The group became so violent that the family who lived there had to abandon the house (see "The Conflict Zone" by Ronan Donovan, National Geographic, 02/2022). 

The same mirror self-recognition effect is found in orangutans and human infants, but not usually in other primate species (the status of gorillas, such as the famous Koko, is controversial).   And not usually in non-primate species, except that there is some evidence for mirror self-recognition in:

However, a comprehensive review by Gallup and Anderson concludes that only human infants and some species of great apes show "clear, consisting, and convincing evidence" for mirror self-recognition ("Self-recognition in animals: Where do we stand 50 years later? Lessons from cleaner wrasse and other species", Psychology of Consciousness, 2019).

Other paradigms have also been employed to document self-awareness in non-primate species.

Back when Gallup first reported his experiments, some behavioristically inclined researchers were having none of it.  In 1981, Robert Epstein and Robert Lanza, working in B.F. Skinner's laboratory, claimed that pigeons could be trained to perform mirror self-recognition, and that what looked like evidence of self-awareness was just a product of operant conditioning, and said nothing about consciousness in nonhuman animals (or humans, for that matter).  Subsequently Uchino and Watanabe (JEAB 2014) confirmed their observations and supported their conclusions.  However, what appeared to be self-directed behavior in pigeons was observed only after an arduous "shaping" regime in which the pigeons were first reinforced for pecking at visible marks on their own bodies, then dots projected on a wall, and then dots observed only in a mirror.  By contrast, self-recognition in chimpanzees (and human infants, for that matter) occurs more or less spontaneously, without any special training.  The chimps may go through a stage where they incorrectly perceive their self-images as other animals, but eventually they (often) come to recognize that the image in the glass is of themselves.  So Epstein et al.'s experiment does not undermine the claims of Gallup and later investigators about mirror-self-recognition.  But they do show the lengths to which radical behaviorists like Skinner would go to avoid talking about consciousness or any other mentalistic construct!  (Epstein was, I believe, Skinner's last graduate student and this paper was one of the last empirical papers that Skinner published.)

Self-Recognition in Solaris

In the great science-fiction film Solaris (Russian-language original scripted and directed in 1972 by Andrei Tarkovsky, based on the novel of the same title by Stanislaw Lem; English-language remake, 2002, by Steven Soderburgh, starring George Clooney), a psychologist, Kris, visits a space station orbiting the planet Solaris that has been the site of mysterious deaths.  It turns out that the planet is a living, sentient organism, which has inserted creatures into the station based on images stored in the cosmonauts' (repressed?) memories.  As soon as Kris gets to the station, he encounters the spitting image of Hari (she's named Rheya in the book), his late wife, who had committed suicide 10 years before.  Searching through his baggage, the woman comes upon a picture of herself, but she does not recognize the image until she views herself, while holding the picture, in a mirror.  It is clear that until that moment she had no internal, mental representation of what she looked like.  

The episode does not appear in Lem's book, which appeared in 1961, long before Gallup's original article was published (at least I can't find it) -- though Lem does have some interesting remarks about Rheya's memory -- she doesn't have much, and one of her memories is illusory.  But Tarkovsky's film appeared in 1972, so he would have had the opportunity to hear about Gallup's findings (which were prominently reported), and incorporate them into the script (losing the material about memory).

064Primate.jpg (51707 bytes)If it really turns out that orangutans have self-recognition, but gorillas do not, the implication is that the capacity for self-recognition arose independently at least twice in primate evolution.  




065Tamarin1.jpg (98665 bytes)The 066Tamarrin2.jpg (61233 bytes) matter is complicated, however, because  Hauser et al. (1995) obtained evidence for mirror self-recognition in cotton-top tamarins, a species of monkeys that are, in evolutionary terms, quite distant from the great apes.  By his account, Hauser succeeded because he took the animals' normal behavioral ecology into account.  However, his methods were criticized by Anderson and Gallup (1997; for a reply, see Hauser & Kralik, 1997).  However, in 2001 Hauser and his colleagues reported that they could not replicate their earlier observations.


Given the results with chimpanzees, investigators have asked whether mirror self-recognition occurs in species other than primates.

Here's a photo, contributed by a neighbor, of her cat watching a diamondback rattlesnake which has come up on her patio.  She reports that the snake "danced", waving back and forth, for about five minutes before slinking away (the cat in the picture was safely on the other side of a sliding glass door).  One commentator suggested that the snake saw its reflection (not just the cat) in the door, and was "dancing" the way it would to challenge another snake.  I suppose you could also suggest that the snake was trying to match its kinesthetic/proprioceptive feedback with what it saw the image doing, in which case maybe even snakes can engage in mirror-self-identification!  Too bad the snake didn't stick around so someone could do the experiment.

Me, I'm a cat person, so I'm always on the lookout for pictures of cats looking in mirrors (and apparently I'm not alone!).


057Dolphin.jpg (36422 bytes)Marten and Psarakos (1994) compared the reactions of bottle-nose dolphins to a mirror placed in their pool, to their reactions to a strange dolphin viewed through a gate.  The dolphins paid more attention to the stranger than to their reflections -- a behavioral difference that might suggest that they recognized themselves.  



059DolphinPhotos.jpg (119995 bytes)In 060DolphinGraph.jpg (82637 bytes)a followup study, Marten and Psarakos (1995) compared reactions to real-time self-views played over a television set installed in the pool, compared to taped playback.  One dolphin (Keola) appeared to discriminate between the two videos, but another (Hot Rod) did not.  Keola also was observed using the video setup to examine a dye mark on his side. 


Gallup has argued that chimpanzees, at least, have bidirectional consciousness: they are responsive to events in the external world, and they are also aware of the relationship between these events and themselves. In his view, this last form of awareness is the hallmark of consciousness.  Still, the fact remains that, even among chimpanzees, not every animal shows mirror self-recognition -- and that must mean something.


Theory of Mind

In another development, Premack and Woodruff (1978) argued that chimpanzees (and perhaps other primates, especially great apes) had a "theory of mind".  In their study, they reported that at least one chimp, namely the famous Sarah, was able to solve novel problems that entailed attributing mental states -- beliefs and desires -- to humans.  After she retired from research, she spent the last 13 years of her life at Chimp Haven, a sanctuary for chimpanzees, and died in 2019 ("The World's Smartest Chimp Has Died", bu Lori Gruen, New York Times, 08/10/2019).

069FoodProb.jpg (99755 bytes) 064SarahNonfood.jpg (98194
                                            bytes) 071Sarah.jpg (50966 bytes)

There's more to be said about the development of consciousness from the phylogenetic point of view, but before we go any further, let's shift for a moment to the ontogenetic view.

What Is It Like To Be an Elephant?  Or an Earthworm?

This is the question raised, and addressed, with a combination of anecdote and rigorous scientific research, by Carl Safina in Beyond Words: What Animals Think and Feel (2015).  Reviewing the book in the New York Review of Books, Tim Flannery wrote ("The Amazing Inner Lives of Animals", 10/08/2015):

Safina comes to an unfamiliar but empirically based conclusion: prior to the domestication of plants and the invention of writing, the differences between human societies and those of elephants, dogs, killer whales, and dolphins was a mater of degree, not kind.  Why, he asks, has it taken us so long to understand this?  Are our egos "threatened by the thought that other animals think and feel?  Is it because acknowledging the mind of another makes it harder to abuse them?

The discovery of nonhuman societies composed of highly intelligent, social, empathetic individuals possessing sophisticated communication systems will force us to reformulate many questions.  We have long asked whether we are along in the universe.  But clearly we are not alone on earth.  The evolution of intelligence, of empathy and complex societies, is surely more likely than we have hitherto considered.  And what is it, exactly, that sets our species apart?  We clearly are different, but in light of Beyond Words we need to reevaluate how, and why. 

Beyond Words will have a deep impact on many readers, for it elevates our relationships with animals to a higher plane.  When your dog looks at you adoringly, even though he or she cannot say it, you can be as sure that love is being expressed as you can when hearing any human declaration of eternal devotion.  Most of us already knew this, but have withheld ourselves from a full surrender to its implications.  ...Beyond Words marks a major milestone in our evolving understanding of our place in nature.  Indeed it has the potential to change our relationship with the natural world.

Most work on animal consciousness focuses on mammals, for the simple reason that they are the most like us in terms of brain structure.  But other animals haven't been neglected.  Consider the following recent book title: What a Fish Knows: The Inner Lives of Our Underwater Cousins by Jonathan Balcombe (2016).  In Other Minds: The Octopus, the Sea, and the Deep Origins of Consciousness (2016), Peter Godfrey-Smith masses evidence that cephalopods, including squid, cuttlefish, and octopus, are highly intelligent -- indeed, the most intelligent of all the "water-bound" animals.  He argues that the octopus, with approximately as many neurons in its brain as a dog has, also has consciousness.  But because the bulk of the octopus's neural mass is located in its tentacles (the word cephalopod is derived from the Greek words for "head" and "foot"), rather than in its head, he claims that the consciousness of an octopus must be very different from our own.

Another book in the same vein is The Inner Life of Animals by Peter Wohlieben (2017), a German forester.    In the later book, he presents mostly anecdotal evidence, drawn from domestic and wild animals, to argue that animals have levels of both intelligence and consciousness that we don't usually appreciate.

In 2016, Stevan Harnad, the founding editor of the highly regarded Behavioral & Brain Sciences, announced a new journal, Animal Sentience, devoted to publishing research on " animal thinking, feeling or well-being". 

In an earlier book, The Hidden Life of Trees: What They Feel, How They Communicate (2016), Peter Wohlieben -- who, after all, began his career as a forester --  animated plants, writing about how they care for their young, feel fear and pain, mourn the death of nearby trees, learn about their environment, etc.  Lincoln Taiz, a plant biologist at UC Santa Cruz, has led a group of critics of Wohlieben's views, arguing that the appearance of intelligence just testifies to the power of evolution by natural selection, and that any thought otherwise just shows how susceptible people are to animism -- especially when it comes to trees (think The Wizard of Oz or The Lord of the Rings).  Wohlieben himself doesn't seem too invested in the idea of tree-consciousness, however, pretty much admitting that he is using metaphor to stimulate his readers to make the same kind of emotional connection to plant life as they do, more naturally, to animal life, and consider that trees, like animals, might be entitled to some kind of rights, or at least deserve some kind of dignity and respect (e.g., No clearcutting old-growth forests!).  But at another level, the idea of consciousness in trees raises the question of consciousness in other kinds of things, like computers and extra-terrestrials, which might have nervous systems very different from ours -- and how we would ever know they have it.

On July 7, 2012, a prominent international group of cognitive neuroscientists, neuropharmacologists, neurophysiologists, neuroanatomists and computational neuroscientists gathered at The University of Cambridge to reassess the neurobiological substrates of conscious experience and related behaviors in human and non-human animals, and signed the portentously named "Cambridge Declaration on Consciousness" asserting that at least some nonhuman animals have consciousness.

For a journalistic account of the debate over intelligence, consciousness, and deliberate intention in plants, see "The Whispering Trees" by Richard Grant, (Smithsonian, 03/2018).

For a photo essay on consciousness, intelligence, and emotion in nonhuman animals, see "What Are They Thinking?" by Yudhijit Bhattacharjee (National Geographic, 10/2022).  The article, which is generally sympathetic to the idea of consciousness across a wide range of species, cites pertinent anecdotal and experimental evidence but also acknowledges the difficulties in making inferences about animal awareness.  As an example, the following caption accompanies the photo (by Anil T. Probhakar) to the left:

Hand up or handout?  A rescued orangutan named Arih reaches toward Syahrul, an employee of the Borneo Orangutan Survival Foundation who has cared for Anih for years.  Anih watched Syahrul struggle to walk in the mucky canal, the photographer says, and finally offered a hand.  The photo went viral, but foundation officials caution against anthropomorphizing animal behavior.  They think Anih probably was asking for food.

The Ontogenetic View

The "theory of mind" (ToM) now plays an important role in theories of cognitive development (e.g., Flavell, 1999) (although ToM researchers do not always acknowledge that the concept has its origins in animal research).

A great deal of ToM research is based on the false-belief task, which assesses whether a child can impute mental states (beliefs and desires) to other people, and understands that his mental states might differ from theirs.  The FBT involves three participants: the child, a puppet, and an experimenter.

  1. First, the experimenter makes the puppet hide a ball in an oatmeal container.
  2. Then the puppet is put away in a cupboard.
  3. Together, the experimenter and the child switch the ball from the oatmeal container to the box.
  4. The puppet is brought back out of the cupboard, and looks for the ball. 
  5. The child is asked where the puppet will look.
    1. 3 to 4-year-old children will typically say that the puppet will look in the box, because "that's where the ball is". 
    2. 4 to 5-year-old children will typically say that the puppet will look in the oatmeal container, because "that where he thinks it is".

Children who pass the FBT show clearly that they recognize that beliefs are mental representations of reality, and that others' beliefs may be different.  By the time they are 60 months old, a clear majority of children pass the FBT.

Simon Baron-Cohen, a British psychiatrist, has characterized the theory of mind as mindreading -- the ability to make inferences about the contents of someone else's mind.  As such, the theory of mind is an important concept in the study of social cognition.  But here we are only interested in ToM as an aspect of consciousness -- the recognition of mental states as such, as representations of reality.

Some neuroscientists have suggested that mindreading is served by a dedicated module in the brain.  Saxe and Kanwisher (2003) conducted an fMRI study in which adults were asked to read three different kinds of stories:

When subjects read the stories about true and false beliefs, the researchers saw increased activation in an area of the brain centered on the temporo-parietal junction, which they dubbed the theory of mind area.  By contrast, another area of the brain, known as the extra-striate body area, which is activated when subjects think about the human body, showed no differential activation.

Now, there's a seeming contradiction here.  If we take mirror self-recognition as our index of consciousness, then human infants have it by the time they're 2 years old.  But if we take the FBT as our index, human children don't have it until they are 4 or 5 years of age.  Which is it?

Clements and Perner (1994) proposed one solution by looking at children's nonverbal behavior in the FBT. When asked, 2- and 3-year-olds will incorrectly say that the puppet will look in the new location (the oatmeal container).  But at the same time, they'll look at the new location (the box).  Apparently, these children have an understanding of the situation that they cannot express verbally, showing what is known as the competence-performance distinction.

Accordingly, more recent investigators have developed non-verbal versions of the FBT to assess the theory of mind in infants (and others) with limited verbal abilities. 

In a truly wonderful study, Onishi and Baillargeon (2005) tested 15-month-old infants on a totally nonverbal version of the FBT.  The experiment depends on the familiar finding that, when infants tend to look longer at counter-expectational events (OK, sometimes they pay less attention to counter-expectational events; still, researchers commonly use looking-time to assess infants' expectations).

In a set of three Familiarization Trials, an actor first hides a plastic watermelon slice in the green box rather than the yellow box.  On two subsequent trials, the actor returns and reaches into the green box.
These were followed by a single belief-induction trial, which was different for each of four conditions.
  1. In the True Belief-Green condition, an actor watched as the yellow box was moved toward the green box.
  2. In the True Belief-Yellow condition, the actor watched as the watermelon slice moved from the green box to the yellow one.
  3. In the False Belief-Green condition, the watermelon slice moved from the green to the yellow box when the actor was not observing.
  4. In the False Belief-Yellow condition, the actor watched as the watermelon slice moved from the green box to the yellow one.  Then, after the actor had disappeared, the slice was moved back to the green box.

Finally, there was a single Test Trial, in which the actor appeared and reached into either the green box or the yellow box.

The results were strikingly clear.
  1. In the TBG condition, the infants looked longer when the actor reached (counterexpectationally) into the yellow box, thus violating her own beliefs about the location of the watermelon.
  2. In the TBY condition, they looked longer when the actor reached into the green box.
  3. In the FBG condition, they looked longer when the actor reached into the yellow box.
  4. And in the FBY condition, they looked longer when the actor reached into the green box.

So, when you test them nonverbally, it appears that even very young infants have at least a rudimentary theory of mind.  They understand that mental states are representations of reality, they know that what others believe might be incorrect, and they expect other people to act in accordance with their beliefs -- and are surprised when they do not.

Now, with a nonverbal version of the FBT in hand, let's ask the obvious question: Does the chimpanzee have a theory of mind as mindreading?  We already know that (some) chimpanzees pass the mirror self-recognition test, and have some degree of consciousness by that standard.  And Premack and Woodruff's study seemed to show that the chimpanzee Sarah, at least, had a theory of mind.  But what we really need is systematic research on a bigger sample of primates.  So...

Back to the Phylogenetic View

Perhaps the best study of the chimpanzee theory of mind was by Call and Tomasello (1998), using a non-verbal version of the FBT.

  1. The chimpanzees were familiarized with a human hider who hid a reward in one of two distinct containers in view of another human communicator.
    1. The communicator had previously proved a reliable informant about the source of food.
    2. In a control condition, the communicator was invisible to the chimpanzee subject.
  2. After the communicator left the room, the hider switched the location of the reward from the old box to a new one, in full view of the subject.
  3. Then the communicator returned to the room and marked the "old" box as correct.  The question, then, is Which location will the chimp choose?

The results were quite clear.  The chimpanzees rarely chose the correct box.  Instead, they chose the box indicated by the communicator.  When 4-year-old human infants were tested on the same situation, they also performed relatively poorly -- though they still performed better than the chimps.  Another group of 5-year-old children, by contrast, almost always made the correct choice, understanding that the communicator's beliefs were incorrect.  So, by this criterion, the chimps lacked a theory of mind.

Similar results were obtained by Hermann et al. (2007), employing the Primate Cognition Test Battery, which you can think of as a sort of "IQ" test for primates. The PCTB consists of a number of subscales, just like the Wechsler or Stanford-Binet IQ tests, assessing performance on a wide variety of tasks.  For our purposes, most interest lies in two tests of the theory of mind: gaze-following and understanding intentions.  In this study, the investigators tested 106 chimpanzees (mean age = 10 years), 32 orangutans (M age = 6 years), and 105 children (M age = 2.5 years).

For the record, the chimps, orangs, and children performed similarly on the tests of spatial and quantitative skills, and also on their understanding of causal relations.

When it came to social skills, however, there were some interesting differences.
  • The children scored well on the test of social learning, but the primates did not.
  • None of the groups performed particularly well on tests of communication.
  • And, most critically, the primates scored particularly poorly on the tests of the theory of mind.

Here are the group comparisons for the two ToM tests taken separately. 

So, if consciousness entails having a theory of mind, then:

But doesn't this contradict the conclusions by Premack and Woodruff, who found evidence that Sarah, at least, did have a theory of mind?  Well, in the first place, Sarah was a very special chimpanzee, who was raised with considerable and intimate contact with her human keepers, and she had acquired a symbolic vocabulary (semantics, anyway, if not syntax).  So it would be hazardous to generalize from her performance.

Moreover, there are some problems with these laboratory studies. 

Based on the evidence available so far, however, Call and Tomasello (2008) offered the following tentative conclusions about "chimpanzee psychology".

This conclusion may seem to violate the Darwinian doctrine of psychological continuity, but there have to be some discontinuities, somewhere, unless you want to start looking for evidence of ToMM in cockroaches.  In commenting on this situation, Povinelli has turned Darwin on his head, reminding us that, despite the continuities uniting species, the whole point of evolution is to add new traits that aren't possessed even by close relatives.  For humans, language appears to be such a trait.  Perhaps consciousness, in the form of ToM, is another.

On the other hand, Frans de Waal (in are We Smart Enough to Know How Smart Animals Are?, 2016) has argued that our assumptions concerning animal intelligence, including consciousness, have been distorted by a kind of human egotism -- that is, by the assumption that animal intelligence (or consciousness) has to be measured by human standards.  Instead, de Waal has argued that the case for animal intelligence is to be made on the animals' own terms, by looking at their behavior in their natural world. 

It's hard to argue with that!  

Still, the line of research on mirror self-recognition initiated by Gallup seems to indicate that chimpanzees, at least, have a rudimentary sense of self.  And that reveals a rudimentary consciousness.

There the matter stood until 2016 when Christopher Krupenye, a postdoctoral fellow working with Tomasello and Call, adapted yet another paradigm already employed in the study of infant ToM to primates.  The paradigm in question anticipatory looking, had previously shown to reveal ToM in human infants.  Humans, including infants, direct their gaze to a location where they expect something to happen.  If infants watch while a human searches for an object, they will direct their gaze toward the location where the human believes the object is, even if the human's belief is false.  So, apparently, do apes.  In their experiment, Krupenye et al constructed two scenarios in which chimpanzees, bonobos, and orangutans watch a human agent search for an object, and they tracked the apes' eye movements while they did so.

In Experiment 1, a human actor (A) looks for "King Kong" (KK), an actor dressed in a sort of gorilla suit.

First come two Familiarization Trials.  In Trial 1, A looks inside two haystacks, then walks towards the door.  KK appears and hits A in the back; A runs inside the door and comes out with a stick, while KK hides in a haystack.  A hits the haystack in which KK is hiding (Target), and KK runs away.  On Trial 2,  KK hides in a haystack, and A hits the other haystack (Distractor).

On False-Belief Test 1, A watches KK hide in one haystack (Target) and then move to the other haystack (Distractor).  A goes in the door and shuts it behind him, while KK runs away.  A comes out of the door with the stick, and walks toward the haystacks.  Where will the subject look?

False-Belief Test 2, A watches KK hide in one haystack (Target), and then runs inside the door.  A does not see KK move to the other haystack (Distractor) and then run away.  A comes out the door with the stick, and walks toward the haystacks.  Where will the subject look?

In Experiment 2, the actor looks for a stone.

In Familiarization Trial 1, A attempts to retrieve a stone through a mesh opening, but KK steals it and hides it under a box (Target) and walks away.  A overturns the correct box (Target) and retrieves the stone.  Trial 2 repeats the scenario with the other box as the Target.

On False-Belief Test 1, KK steals the stone, and A watches KK hide the stone under one box (Distractor, then move to the other box (Target), and finally holds the Distractor box.  KK then threatens A, who leaves the room and shuts the door behind him, and KK runs away with the stone.  A returns and reaches toward the boxes.  Where will the subject look?

On False-Belief Test 2
, KK steals the stone and (P) hides it under one box while A watches.  After A leaves the room, KK moves the stone to the other box and then removes the stone again and runs away with it.  A returns and reaches toward the boxes.  Where will the subject look?

The answer is that most of the apes directed their first look to the location where the Actor thought KK or the stone would be, given his knowledge.  The apes knew better, of course, but they expected the Actor to act in accordance with his beliefs, not their own.  This is the essence of the False Belief test, and the apes passed it by looking where they expected the Actor to look, based on their understanding of his (false) belief.  At least most of them did.  Most of the apes passed one or the other test, and many of them passed both of them

Here are links to videos of two subjects' performance on the two experiments (one each for Experiment 1 and Experiment 2).  The subject can be seen in the upper left-hand corner, and the red dots indicate where he or she is looking.  You may need to be connected to the UCB network (either directly, via AirBears, or VPN), or otherwise have access to the Science website to view these videos.

Krupenye et al. conclude that great apes -- at least some chimpanzees, bonobos, and orangutans -- do possess a theory of mind after all.  They anticipate the goal-directed behavior of some agent, and attribute mental states -- at least, states of belief to an agent, even if these beliefs are incongruent with reality.  Actually, Krupenye et al. argue that these apes have an implicit if not explicit understanding of false beliefs (I would prefer the term covert to implicit, because I want to reserve the term "implicit" for unconscious percepts, memories, thoughts, and the like).  Although not reflected in their own overt behavioral choices, as indicated by their poor performance on other ToM tests, their understanding of false beliefs is reflected in their covert anticipatory looking behavior.

Krupenye et al conclude: "that great apes operate, at least on an implicit level, with an understanding of false beliefs suggested that this essential TOM skill is likely at least as old as humans' last common ancestor with the other apes" (p. 113).

The Evolution of Machine Consciousness

According to some "futurists", we are quickly heading into a new stage of evolution, satirized by Roz Chast in this cartoon (New Yorker, 11/01/2021).  One in which computers will surpass humans in intelligence, and even become conscious like ourselves (or more so).  The chief proponent of this idea is Ray Kurzweil, in books like the Age of Intelligent Machines (1990), The Age of Spiritual Machines (1999), The Singularity is Near: When Humans Transcend Biology (2005), and How to Create a Mind: the Secret of Human Thought Revealed (2012).  There are others, including the 4th Revolution: How the Infosphere is Reshaping Human Reality by Luciana Floridi (2014) and Superintelligence: Paths, Dangers, Strategies by Nick Bostrom (2014). 

The evolution of machine intelligence begins in the medieval period with the construction of robots -- machines designed to perform some humanlike task (like serving wine -- see illustration at the left).  For an interesting survey of these devices in medieval Europe, see Medieval Robots: Mechanism, Magic, Nature, and Art (2023) by Elly R. Truit.  The figure at left is from a 15th-century illustrated edition of The Travels of Marco Polo, originally published in the 13th century, in which the author refers to a magical machine that fills goblets automatically.  

Why shouldn't machines be intelligent?  And if they achieve a certain level of complexity, why shouldn't they be conscious?  If, as Marvin Minsky argued, the brain is a computer (or a machine) made of meat Minsky, M. ("Why People Think Computers Can’t", AI Magazine, 3(4), 1982), and brains are conscious, then there's no principled reason why computers (or other machines), made out of other substances (silicon chips, or beer cans tied together with string) could not also become conscious.  It's just a matter of having sufficient computational power -- and the right program.  The claim that, at a certain level of organization, information-processing machines might become conscious is fairly explicitly stated in Chalmers's theory of consciousness, discussed in the lectures on The Mind-Body Problem.

Reviewing the books by Floridi and Bostrom, John Searle makes some critical points that suggest, to me at least, serious problems with the idea that computers could become conscious, simply by virtue of massive information-processing power ("What Your Computer Can't Know", New York Review of Books, 10/09/2014; for a subsequent exchange with Floridi, see "At the Information Desk", NYRB, 12/18/2014). 

First, remember from the lectures on Introspection that the essence of consciousness is subjectivity: there is something it's like to be conscious.  But Searle's basic point is that consciousness is observer-relative, and so is information.  Therefore, the concept of information can't provide an objective, third-person account of subjective, first-person experience because information is also observer-relative. 

Let's review Searle's take on the objective-subjective distinction, which turns out to be a lot more complicated than it first appears.  In what follows, I use examples from Searle's 2014 review.

Searle then goes on to clarify certain assumptions about ostensibly "intelligent" computers -- essentially, repeating his famous "Chinese Room" argument against Strong Artificial Intelligence..

It follows from this that digital computers don't have any observer-independent intelligence at all.  All of their intelligence is observer-relative, because it has been built into the computer by a programmer who has real, intrinsic, observer-independent consciousness and intelligence. 

And it follows, too, that everything that a digital computer does is, in Searle's terms nonconscious.  It simply implements a program that has been written by a conscious agent.  It doesn't think, or feel, or desire anything -- it simply executes a program that has been created by a conscious programmer.

Searle also discusses the nature of information, making some points that are critical for understanding the possibility of computer consciousness.

Recall that David Chalmers's theory of consciousness is panpsychist, because he proposes that any physical system that represents information is conscious.  Thus, thermostats and solar systems are conscious, to the extent that they can represent information.  The implication is that computers are conscious, too, or at least they can be conscious, once they approach the information-processing capacity of the human brain, with its 100 billion neurons and 100 trillion synaptic connections between them.  It is this kind of argument that leads some theorists to conclude that computers can, in principle, become conscious entities, once they become powerful-enough information processors. 

In addressing this argument, Searle reminds us that there are two kinds of information.

Searle argues, first, that the computations performed by machines such as computers are observer-relative.  All the machine does is to manipulate physical symbolsThese physical symbols (for example, of 0s and 1s) may represent something, like words and numbers; but whatever they represent, they represent it my virtue of some interpretation which has been placed on them -- for example, by a programmer.

 The LaMDA Brouhaha at Google

In 2002, a controversy erupted at Google when Blake Lemoine, one of its software engineers, publicly announced on Medium, an idea-sharing social network, that one of the company's computational  systems, a "large language model" (LLM) known as the Language Model for Dialogue Applications (LaMDA) was, in fact, "sentient".  It didn't just make meaningful, appropriate responses to verbal input, carrying on conversations.  It's a souped-up version of Joseph Weizenbaum's ELIZA program, which simulated a "Rogerian" psychotherapist, coupled with a knowledge base like Watson, the IBM supercomputer that defeated two GOAT champions at "Jeopardy!" -- except, so Lemoine claimed, LaMDA actually knew what it was talking about. 

For a short but provocative essay on the political economy of artificial intelligence, see "You Talking to Me?" by Dwayne Monroe, The Nation, 06/25/2022.

Following up on the LaMDA Brouhaha, the introduction of other, even more sophisticated Large Language Models like ChatGPT led some users to have the impression that they were, in fact, interacting with a sentient being -- thus, at least to some extent, passing a version of the Turing Test.  Maybe that was a little overenthusiastic in 2023, but the very question of whether an AI system could actually possess consciousness has led a number of cognitive scientists to try to figure out how we would know.  To that end, Patrick Butlin, Robert Long, and their colleagues (a collection of philosophers, cognitive scientists, and neuroscientists) surveyed a number of prominent theories of consciousness, including some discussed in this course, and assembled a list of 14 potential "indicators" that an AI system might be conscious.  For example, Global Workspace Theory asserts that a conscious system should have a limited capacity workspace that is accessible to all of the system's processing modules.  And the Higher Order Theory (HOT) a the 14 indicatorssserts that a conscious system must have some form of metacognitive monitoring.  The image on the left summarizes the 14 indicators.  For the complete report, see https://arxiv.org/abs/2308.08708.  The report provides a very good summary of various computer-inspired theories of consciousness. 

Of course, none of these theories yield neural indicators of consciousness, because computers don't have neurons.  Instead, they are based on theories of cognitive or computer architecture.  Thus, Baars, who was trained as a psychologist, identifies consciousness with something like working memory, and postulates connections to other modules that perform various cognitive tasks.  Rosenthal's HOT theory identifies consciousness with metacognition.

For the record, none of the AIs evaluated by these authors came even close to meeting the criteria for consciousness, as specified by these indicators.  Even to achieve just this level of success, the indicators, and the architectures, had to be defined very broadly.

It's nice to propose various indicators of consciousness, but its another thing entirely to figure out how those indicators are indicated (as it were).  For example, it's an easy matter to build a system with something like working memory built into it: that's what a memory buffer is.  And its also an easy matter to build a system out of a bunch of task-specific modules.  But while a conscious system might have to have something like working memory with input and output connections to various modules, nobody claims that a computer system, like a network of computers, that has these properties is necessarily conscious.  So something more is required.

What's required to generate sentience is something like metacognition -- the awareness that one is the thing that's doing the thinking.  We can measure that in humans -- that's what tests of the theory of mind are for, for example.  But how are we going to do that with a machine? 

And finally, consciousness has to do with the self -- one's awareness that one's thoughts,feelings, and desires are one's own, and not necessarily shared by others.  In other words, in order to have consciousness an AI is going to have to have a self.  And "self" is a concept that's missing from Butlin and Long's list.

The Large Language Models that support contemporary approaches to AI are based on "connectionist" architectures familiar in cognitive psychology, as discussed in my lectures on Neuroscientific and Computational Models of Memory.    An article in the New Yorker profiled Geoffrey Hinton, one of the earliest proponents of connectionist modeling and for that reason sometimes called "the godfather of AI".  in 2017, he shared the Turing Award, often called the "Nobel Prize" in computer science, with and Yann Bengio Le Cun for their work on "deep learning" by machines.  The profile ("Metamorphosis" by Joshua Rothman, 11/20/2023) is absolutely fascinanting, including these remarks (by Rothman) on the relation between AI and human intelligence:
How should we describe the mental life of a digital intelligence without a mortal body or an individual identity? In recent months, some A.I. researchers have taken to calling GPT a “reasoning engine”—a way, perhaps, of sliding out from under the weight of the word “thinking,” which we struggle to define. “People blame us for using those words—‘thinking,’ ‘knowing,’ ‘understanding,’ ‘deciding,’ and so on,” Bengio told me. “But even though we don’t have a complete understanding of the meaning of those words, they’ve been very powerful ways of creating analogies that help us understand what we’re doing. It’s helped us a lot to talk about ‘imagination,’ ‘attention,’ ‘planning,’ ‘intuition’ as a tool to clarify and explore.” In Bengio’s view, “a lot of what we’ve been doing is solving the ‘intuition’ aspect of the mind.” Intuitions might be understood as thoughts that we can’t explain: our minds generate them for us, unconsciously, by making connections between what we’re encountering in the present and our past experiences. We tend to prize reason over intuition, but Hinton believes that we are more intuitive than we acknowledge. “For years, symbolic-A.I. people said our true nature is, we’re reasoning machines,” he told me. “I think that’s just nonsense. Our true nature is, we’re analogy machines, with a little bit of reasoning built on top, to notice when the analogies are giving us the wrong answers, and correct them.”? 

The Cultural View

In addition to the phylogenetic and ontogenetic views familiar to psychology, there is another view of development that can be found in other social sciences, such as economics and political science.  This is a cultural view of development, by which it is held that societies and cultures develop much like species evolve and individuals grow.

The origins of this cultural view of development lie in the political economy of Karl Marx, who argued that all societies went through four stages of economic development:

To which, Marx and Engels later added two other stages:

In 1960, the American economic historian W.W. Rostow offered a non-Marxist alternative conception of economic growth which he called the stages of growth:

Along the same lines, in 1965 A.F.K. Organski, a comparative political scientist, proposed four stages of political development:

Most recently, Francis Fukuyama traced political development through a series of stages in the Origins of Political Order: From Prehuman Times to the French Revolution (2011); a second volume, forthcoming as of 2012, will track political development since the French Revolution of 1789.  According to his view:

Stage theories of political and economic development are about as popular in social science as stage theories of cognitive or socio-emotional development have been in psychology!  

Note, however, the implications of the term development, which suggests that some societies are more "developed" -- hence, in some sense better -- than others.  Hence, the familiar distinction between developed and undeveloped or underdeveloped nations.  The implication is somewhat unsavory, just as is the suggestion, based on a misreading of evolutionary theory, that some species (e.g., "lower animals") are "less developed" than others (i.e., humans).  For this reason, contemporary political and social thinkers often prefer to talk of social or cultural diversity rather than social or cultural development, thereby embracing the notion that all social and cultural arrangements are equally good.


Class-Consciousness and Consciousness-Raising

With the exception of Marx, few of these social scientists have had much to say about the correlates between the economic and political development of whole societies and cultures, and the psychological development of the individuals who live in them.  For Marx, however, it was important that industrial workers develop a class consciousness -- an awareness of the class structure of the society that oppressed them -- as a precondition to the revolution(s) that would overthrow bourgeois capitalism in favor of socialism and, eventually, communism.  Mao Tse-tung required the same class consciousness of the peasants who were to lead the revolution in pre-capitalist, feudal China.

Marx specifically discussed the development of consciousness in the preface to his Contribution to the Critique of Political Economy (1859):

The general conclusion at which I arrived and which, once reached, became the guiding principle of my studies can be summarized as follows.  In the social production of their existence, men inevitably enter into definite relations, which are independent of their will, namely relations of production appropriate to a given stage in the development of their material forces of production.  The totality of these relations of production constitutes the economic structure of society, the real foundation, on which arises a legal and political superstructure and to which correspond definite forms of social consciousness.  The mode of production of material life conditions the general process of social, political, and intellectual life.  It is not the consciousness of men that determines their existence, but their social existence that determines their consciousness.  

118Dubois.jpg (158039
                                        bytes)This Marxist notion of consciousness can also be found in the work of  W.E.B. DuBois (pronounced Doo-Boyz; 1868-1963), the African-American scholar who wrote in The Souls of Black Folk (1903) about the "double consciousness" of the American Negro (as African-Americans were then called), who is aware of himself as both American and Negro.  



A related concept can be found in the works of the French-West Indian psychiatrist and social philosopher Frantz Fanon (1925-1961) -- especially in Black Skin, White Masks (1952).

In the late 1960s, this Marxist concept of consciousness could be found in the literature of the women's movement, as in the efforts of first-wave feminists such as Kate Millett to engage in "consciousness-raising" activities that would make women aware of their oppression by men (and, for that matter, men aware of their roles as oppressors).

Capping off the "Sixties Countercuture", at least so far as consciousness is concerned, Charles Reich, legal scholar, wrote The Greening of America (1970), in which he described three stages in the evolution of cultural consciousness:

  1. Consciousness I was highly individualistic, and characteristic of a pre-industrial society in which everyone was more or less on his own (think of the 19th-century western frontier)..
  2. Consciousness II, characteristic of industrial development, which is dominated by interlocking systems, organizational hierarchies, and corporate interests (think of The Gilded Age and "Mad Men").
  3. Consciousness III, focused on individual self-definition, direct action, and the power of the community (think of hippies and the rest of the counterculture).

But little of this had anything to do with scientific psychology or cognitive science. 

In fact, however, some psychologists in the Soviet Union who were influenced by Marx, including Lev Vygotsky, did explore the relations between economic development of society and the cognitive development of individuals.   In the West, this line of research was pursued most avidly by the Michael Cole, Silvia Scribner, and their colleagues at the Center for Comparative Cognition at UC San Diego.  These investigators explored, such topics as literacy as a force in cognitive development.  However, these researchers and theorists have had little to say about consciousness per se.

But that doesn't mean that the cultural development of consciousness has been ignored entirely. 


Mirrors and Mirror Self-Recognition

If mirror self-recognition is your criterion for consciousness, then it's pretty clear that we've had it for a very long time. Archeological digs in Turkey have yielded mirrors, made of polished stone, dating to roughly 6,000 BC. And before that, early humans could see their reflections in pools of water (remember the myth of Narcissus). But how did they react? Did they recognize themselves? They did: jewelry such as beads has been found in some of the earliest Paleolithic cave-dwellings. This indicates that our earliest human ancestors knew what they looked like, and cared about it. (At least once they had been expelled from the Garden of Eden -- see below.)



The Origins of Consciousness in the Breakdown of the Bicameral Mind

119Jaynes.jpg (95051
                                        bytes)In The Origins of Consciousness in the Breakdown of the Bicameral Mind (1977), Julian Jaynes offered the beginnings of an account of the cultural development of consciousness.  Recall (from the Introduction) that Jaynes was able to find relatively few references to mental life in early Western literature, until roughly the 6th century B.C.  



Consciousness in the Iliad and the Odyssey

120Iliad.jpg (94296 bytes)For example, Jaynes points out that there is little or no evidence of consciousness in Homer's Iliad.  With rare exceptions, nobody makes decisions, introspects, or reminisces.  The people in Homer pretty much just do what the gods tell them to do.  


Here are some examples:

The point here is that there's a lot of emotion in the Iliad, and plenty of desire, but not too much by way of thinking, choosing, and desiring.  It's as if the people of the Iliad are operating on what Robert McCarley called the "Reptilian Brain" (the brainstem and cerebellum) and the "Old Mammalian Brain" (the limbic system).

Actually, that's not strictly true.  Achilles, whose pride and wrath are the subject of the Iliad, made a choice: "between a long, insignificant life and a brief, glorious one" (Daniel Mendelsohn, "Battle Lines", New Yorker, 11/07/2011).  That's why he's so angry with Agamemnon: Agamemnon, who had to give up one of his slave girls, took one of Achilles' -- thus depriving Achilles of one of the spoils of war, and in turn threatening Achilles' reputation.  So Achilles decides not to fight any longer, thus depriving the Greeks of their best warrior -- at which point the war starts going badly for them.  And later on, he decides to rejoin the battle.  And at the end, he decides to return Hector's body to Priam.

In the Odyssey (Book XI), by the way, Achilles even changes his mind.  When Odysseus encounters him in the Underworld (Hades), and greets him as "blessed in life, blessed in death" he responds that "I'd rather serve as another man's laborer, as a poor peasant without land, and be alive on Earth, than be lord of all the lifeless dead".

Helen, too, sometimes displays glimmers of consciousness.  When she stands on the walls of Troy, identifying for Priam the Greeks who have massed to attack him, she seems to regret what she has done. Mostly, though, she just names the warriors and the cities they represent.

But the Iliad is a long poem, and there's not a lot of consciousness in it.  At least, not a lot of free will, choice, and decision-making.  After all, Helen wasn't Achilles' wife.  He's gone to battle because Agamemnon requires it.  And it's not as if Helen eloped with Paris of her own free will.  She was given to him by Aphrodite.  And there's no reason to think that Paris had any thought about Helen until Aphrodite offered her as a bribe -- he didn't even know that Helen was already married.

121Odyssey.jpg (138531 bytes)There's consciousness aplenty in Homer's Odyssey, however.


Here are some examples:

(I hear you objecting, "What about the Trojan Horse?".  But the story of the Trojan Horse isn't in the Iliad.  It's in the Odyssey (Books IV and VIII; also Euripides's Trojan Women and Virgil's Aeneid, Book II)  -- and it was Odysseus's idea!  Odysseus is a different sort of man, with a different sort of mind.
Jaynes also points out that certain Greek words, which have mentalistic connotations in later Greek, lack these connotations in Homer.

There are other examples from ancient Greek literature.  In the story of Jason and the Argonauts, for example, dating from the 3rd century BCE, we have a scene in which Jason, who has been the Golden Fleece by King Aietes, but only if he will perform certain tasks, thinks hard about what he should do.

Dating Homer

Homer, of course, may not have ever lived at all, or there may have been many "Homers".  The general view is that "Homer", whoever he was, collected and arranged the Iliad and the Odyssey sometime in the 8th century BCE, based on earlier oral traditions.  Adam Nicolson, in Why Homer Maters (2014), argues that the epics represent "the violence and sense of strangeness of about 1800 B.C.".

Bryan Doerries, reviewing Nicolson's book in the New York Times Book Review ("Songs of the Sirens", 12/28/2014), suggests that "the ancient poems appear as a bridge between the present and an otherwise inaccessible past, a rare window into a moment of cultural convergence around 2000 B.C., when East met West, North met South, and Greek consciousness was forged in the crucible of conflict between a savage warrior culture from the flat grasslands of Eurasia and the wealthy, sophisticated residents of cities in the eastern Mediterranean." 

The Iliad and the Odyssey, Nicholson writes, constitute "a miracle of transmission from one end of human civilization to the other."


Consciousness in the Hebrew Bible

And in a provocative analysis of the Hebrew Bible, 

  • Jaynes suggests that the prophet Amos, whose book was written about 800 BCE, was a "left-over bicameral person".  Amos is always saying things like "Thus sayest the Lord...".  

  • And he contrasts Amos with Ecclesiastes, whose book was written about 200 BCE, whose prophecies are couched quite differently -- e.g., "I saw in my heart that wisdom exelleth folly". 

Amos is repeating God's word;  Ecclesiastes is thinking for himself.

Julian Jaynes in the Garden of Eden


                                                        (213617 bytes)Actually, the book of Genesis itself contains a kind of foreshadowing of Jaynes's argument that consciousness had its origin -- if not in historical time, then in prehistoric time after the appearance of humans on the scene.  The illustrations from The Book of Genesis as illustrated by the great comics author and illustrator R. Crumb (as published in the New Yorker,  06/08-15/2009).




                                                        (90810 bytes)To make a long story short.  On the sixth day of creation, God created man in His own image, and planted a garden in Eden, with the Tree of Life in the middle.  God also planted the Tree of Knowledge of Good and Evil, but cautions Adam and Eve not to eat from it.  But Eve was tempted by the Serpent to eat of the Tree of Knowledge, and persuaded Adam to do the same.  At that point "the eyes of the two were opened, and they knew that they were naked", and they made loincloths out of fig leaves.  This is their first moment of self-awareness.  Before that, they didn't know that they were naked, nor had they any reason to be ashamed of the fact.  Then they heard God walking through the Garden, and they tried to hide from Him.  This is the first time they demonstrate a "theory of mind": they think that God can't see them if they hide in the trees.  



So, before they ate of the Tree of Knowledge of Good and Evil, Adam and Eve weren't conscious in the same way that they were afterwards.  Before, they weren't aware that they were naked, or that nakedness was bad.  And before, they didn't think about what God could see.  Afterwards, they were conscious in both respects.

The Genesis story of Adam and Eve is short and sweet -- well, bittersweet.  God creates Adam, then Eve.  They eat the forbidden fruit of the Tree of Knowledge of Good and Evil and get kicked out of the Garden of Eden before they can eat the forbidden fruit of the Tree of Life.  Together they beget Cain and Abel, but Cain kills Abel, so they beget Seth.  Seth begets Enos (somehow; don't ask), and that's the last we hear of Adam and Eve.

Here's how it goes, in the King James version (Chs. 2-4).

2. [15] And the LORD God took the man, and put him into the garden of Eden to dress it and to keep it.   [16] And the LORD God commanded the man, saying, Of every tree of the garden thou mayest freely eat:  [17] But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die.  [18] And the LORD God said, It is not good that the man should be alone; I will make him an help meet for him.  [19] And out of the ground the LORD God formed every beast of the field, and every fowl of the air; and brought them unto Adam to see what he would call them: and whatsoever Adam called every living creature, that was the name thereof.  [20] And Adam gave names to all cattle, and to the fowl of the air, and to every beast of the field; but for Adam there was not found an help meet for him.  [21] And the LORD God caused a deep sleep to fall upon Adam and he slept: and he took one of his ribs, and closed up the flesh instead thereof;  [22] And the rib, which the LORD God had taken from man, made he a woman, and brought her unto the man.  [23] And Adam said, This is now bone of my bones, and flesh of my flesh: she shall be called Woman, because she was taken out of Man.  [24] Therefore shall a man leave his father and his mother, and shall cleave unto his wife: and they shall be one flesh.  [25] And they were both naked, the man and his wife, and were not ashamed.

3. [1] Now the serpent was more subtil than any beast of the field which the LORD God had made. And he said unto the woman, Yea, hath God said, Ye shall not eat of every tree of the garden?  [2] And the woman said unto the serpent, We may eat of the fruit of the trees of the garden:  [3] But of the fruit of the tree which is in the midst of the garden, God hath said, Ye shall not eat of it, neither shall ye touch it, lest ye die.   [4] And the serpent said unto the woman, Ye shall not surely die:  [5] For God doth know that in the day ye eat thereof, then your eyes shall be opened, and ye shall be as gods, knowing good and evil.   [6] And when the woman saw that the tree was good for food, and that it was pleasant to the eyes, and a tree to be desired to make one wise, she took of the fruit thereof, and did eat, and gave also unto her husband with her; and he did eat.  [7] And the eyes of them both were opened, and they knew that they were naked; and they sewed fig leaves together, and made themselves aprons.  [8] And they heard the voice of the LORD God walking in the garden in the cool of the day: and Adam and his wife hid themselves from the presence of the LORD God amongst the trees of the garden.  [9] And the LORD God called unto Adam, and said unto him, Where art thou?  [10] And he said, I heard thy voice in the garden, and I was afraid, because I was naked; and I hid myself.  [11] And he said, Who told thee that thou wast naked? Hast thou eaten of the tree, whereof I commanded thee that thou shouldest not eat?  [12] And the man said, The woman whom thou gavest to be with me, she gave me of the tree, and I did eat.  [13] And the LORD God said unto the woman, What is this that thou hast done? And the woman said, The serpent beguiled me, and I did eat.  [14] And the LORD God said unto the serpent, Because thou hast done this, thou art cursed above all cattle, and above every beast of the field; upon thy belly shalt thou go, and dust shalt thou eat all the days of thy life:  [15] And I will put enmity between thee and the woman, and between thy seed and her seed; it shall bruise thy head, and thou shalt bruise his heel.  [16] Unto the woman he said, I will greatly multiply thy sorrow and thy conception; in sorrow thou shalt bring forth children; and thy desire shall be to thy husband, and he shall rule over thee.  [17] And unto Adam he said, Because thou hast hearkened unto the voice of thy wife, and hast eaten of the tree, of which I commanded thee, saying, Thou shalt not eat of it: cursed is the ground for thy sake; in sorrow shalt thou eat of it all the days of thy life;  [18] Thorns also and thistles shall it bring forth to thee; and thou shalt eat the herb of the field;  [19] In the sweat of thy face shalt thou eat bread, till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return.  [20] And Adam called his wife's name Eve; because she was the mother of all living.  [21] Unto Adam also and to his wife did the LORD God
make coats of skins, and clothed them.  [22] And the LORD God said, Behold, the man is become as one of us, to know good and evil: and now, lest he put forth his hand, and take also of the tree of life, and eat, and live for ever:  [23] Therefore the LORD God sent him forth from the garden of Eden, to till the ground from whence he was taken.  [24] So he drove out the man; and he placed at the east of the garden of Eden Cherubims, and a flaming sword which turned every way, to keep the way of the tree of life.

4. [1] And Adam knew Eve his wife; and she conceived, and bare Cain, and said, I have gotten a man from the LORD.
[2] And she again bare his brother Abel. And Abel was a keeper of sheep, but Cain was a tiller of the ground....

5. ...[25] And Adam knew his wife again; and she bare a son, and called his name Seth: For God, said she, hath appointed me another seed instead of Abel, whom Cain slew.  [26] And to Seth, to him also there was born a son; and he called his name Enos: then began men to call upon the name of the LORD.....

John Milton, in Paradise Lost (1667), had other ideas about "prelapsarian" life -- that is, life before The Fall.  In Books 4-9, Milton gave Adam and Eve a whole domestic life before they ever ate the apple (as it were).  Adam and Eve talk, eat and drink (they even have the Archangel Rafael over for dinner), walk around the Garden, play with the animals, socialize with angels, sleep and dream, fight and make up, make love -- just like any 21st-century couple (except maybe for the bit about talking with the angels).

For more on Milton's portrayal of Adam and Eve, and especially its implications for modern (i.e., post-17th century) views of consciousness, see Coming To: Consciousness and Natality in Early Modern England (2022) by Timothy Harrison, reviewed by Catherine Nicholson in "Improving Paradise", New York Review of Books, 06/23/2023.  They point out that before Descartes,  consciousness was essentially a moral faculty -- as in consciousness of sin, acquired by eating of the Tree of Knowledge of Good and Evil.  But after Descartes, consciousness was a cognitive faculty, having to do with one's awareness of oneself as a thinking being.  Before The Fall, in Milton's revisionist view, Eve describes her earliest memories as "unexperienced thought"; it's not clear exactly what she means by this, however, but she seems to mean thought that is unreflective -- thoughts without the experience of thinking; thought without self-reflection. 

Still, even before The Fall, Adam and Eve seem to be groping toward self-awareness.  Maybe, aleady under the influence of Descartes, Milton couldn't imagine human existence without consciousness.  In Adam's earliest memory, he asks the animals "Tell, if ye saw, how came I thus, how here?".  Eve, for her part, seems to have been the first subject in the Mirror Test when, shortly after her creation (this is her earliest recollection) she encountered a body of water -- and she fails:

...I thither went
With unexperienced thought and laid me down
On the green bank to look into the cl.ear
Smooth lake that to me seemed another sky.
As I bent down to look, just opposite,
A shape within the watery gleam appeared
Bending to look on me; I started back;
It started back.  But pleased I soon returned;
Pleased it returned as soon with answering looks
Of sympathy and love

More conventionally, here's how Thomas Hardy (1840-1928), the British novelist and poet, put it in his poem, "Before Life and After":

A time there was—as one may guess
And as, indeed, earth's testimonies tell—
Before the birth of consciousness,
When all went well.

None suffered sickness, love, or loss,
None knew regret, starved hope, or heart-burnings;
None cared whatever crash or cross
Brought wrack to things.

If something ceased, no tongue bewailed,
If something winced and waned, no heart was wrung;
If brightness dimmed, and dark prevailed,
No sense was stung.

But the disease of feeling germed,
And primal rightness took the tinct of wrong;
Ere nescience shall be reaffirmed
How long, how long?

For more on Adam, Eve, and what might have gone on in the Garden of Eden, see:

  • Adam, Eve, and the Serpent (1988) by Elaine Pagels, a biblical scholar (among other things), discusses the role of Adam and Eve in the development of Western attitudes towards gender, sexuality, and sin.
  • The First Love Story: Adam, Eve, and Us (2017) by Bruce Feiler, author of Walking the Bible.  As its title indicates, the book focuses mostly on the personal relationship between Adam and Eve, but he does have this to say about our preferred topic:  "Eve is the first teacher, the first to trust her eyes, the firs who wants to know.  In so doing, she becomes the first to commit the ultimate modern act of not accepting the meaning of others but insisting on making meaning yourself.  She writes her own story."
  • The Rise and Fall of Adam and Eve (2017) by Stephen Greenblatt, a scholar of Renaissance literature (among other things), traces the history of Adam and Eve from before Genesis (specifically, the Babylonian epic of Gilgamesh), through Judaism, Christianity, and Islam, to the "just-so story of secular humanism, and ranging over literature, art, and biology as well as theology.  Did Adam and Eve have sex before The Fall?  Did they even talk to each other?  Greenblatt has the provocative answers.
    • See the review by A.N. Wilson ("When Our Eyes Were Opened", Wall Street Journal, 09/09/2017).
    • And by Marina Warner ("Legends of the Fall", New York Review of Books, 09/28/2017).
    • And by Marilynne Robinson ("The Truth and Fiction of Adam and Eve", New York Times, 10/06/2017).

Bicameralism and Its Breakdown

By analogy to the bicameral legislature (or, perhaps to the bicameral camel!), Jaynes suggests that these early humans possessed a bicameral mind consisting of a "decision-making part" and a "follower part".  Mostly, humans of this time were creatures of habit.  But when something frustrated their habitual behavior, or called for a novel response, the stress of decision instigated auditory hallucinations, which early humans interpreted as the gods telling them what to do.

Writing in 1976, at a time when knowledge of hemispheric specialization was just beginning to emerge, Jaynes sometimes identified the decision-making part with the "silent" right hemisphere, and the following part with the left hemisphere.  But Jaynes didn't believe that, all of a sudden, one hemisphere got connected with another.  After all, there has been no change in the human genome since Adam and Eve -- 6000 years simply isn't enough time.  Rather, Jaynes attributes the development and breakdown of bicamerality to cultural changes -- to developments taking place in society, rather than in species or individuals.

Jaynes finds evidence of bicamerality in the most ancient writings, so in his view the bicameral mind was in operation at least by the invention of writing, about 3000 BCE. In fact, Jaynes believes that bicamerality emerged in the shift from hunter-gatherer mode to agriculture, as a way of controlling large groups of people through a rigidly ordered social hierarchy with a god at the top, speaking through a kind, who told everybody else what to do.  Think of Moses bringing the Ten Commandments down from Mount Sinai.

Similarly, Jaynes traces the beginnings of the breakdown of the bicameral mind to about 1400 BCE, when large civilizations naturally produced lots of "voices", who often didn't agree with each other.  At that point, people stop listening to gods and start thinking for themselves.  Or, perhaps, people simply found that the gods didn't talk to them anymore.  It's about this time that literature is full of references to people being abandoned by their gods, as in the Psalmist's "My God, My God, why has thou forsaken me?".

Anyway, Jaynes argues that the breakdown was fully consolidated by about 600 BCE -- when Solon initiated the Golden Age of Greece with the adage, "Know thyself". 


The "Axial Age"

Jaynes identifies similar trends occurring at about the same time in China and India. Actually, the entire period from about 800 to 200 BCE has come to be known as the Axial Age -- a term (an axis is a pivot) coined by the German philosopher Karl Jaspers in his treatise On the Origin and Goal of History (1949). Jaspers pointed out that the period from about 800 to 200 BC was characterized by a revolution in religious and philosophical thought, in which "the spiritual foundations of humanity were laid simultaneously and independently" in very different parts of the world:

  • China (Confucius, 551-479 BCE);
  • India (Buddha, 563-483 BCE);
  • Israel (many of the Hebrew Prophets, including Elijah, 9th c.; , Isaiah, 8th c.; Jeremiah,7th c.; and Deutero-Isaiah, 6th c.)
  • Persia (Zoroaster, whom Jaspers dated in the 6th c., although more recent scholarship pushes that date back;
  • Greece (Socrates, 469-399 BCE; Plato, c. 428-348; Aristotle, 384-322 BCE).

The Axial Age is usually viewed as a turning point in the history of religion -- and, in particular the establishment of monotheism -- based on a transcendental vision of the presence and power of a divine entity. But it also was a turning point in philosophy. As Jaspers put it, "For the first time there were philosophers". Confucius, Gautama Buddha, and Socrates thought for themselves, and thought about thinking, and initiated a tradition in which thinkers exchanged their thoughts and debated with each other. Beginning about 800 BC, and for the first time, people began to reflect on themselves and their society.

  • Confucius taught that men should think for themselves.
  • Buddha taught that suffering was caused by particular modes of thought.
  • Socrates taught that knowledge could be obtained by reason, while Aristotle taught that knowledge came from experience.

For a highly readable treatment of the Axial Age, with special emphasis on its place in the history of religion, see The Great Transformation: The Beginnings of Our Religious Traditions (2006) by Karen Armstrong, a historian of religion (she also wrote A History of God, 1993). See also The Axial Age and Its Consequences, a collection of papers by sociologists and historians edited by Robert N. Bellah and Hans Joas (2013; reviewed in "A Different Turning Point for Mankind?" by G.W. Bowersock, New York Review of Books 05/09/2013).


Philological Critiques of Jaynes

Jaynes' arguments are certainly provocative, but he was not the only person to have this idea.  Reviewing a new translation of the Odyssey by Emily Wilson, Gregory Hays, a classics scholar at the University of Virginia, reminds us that "Aristotle said that the "Iliad" was a poem in which things happened to people, while the "Odyssey" was a poem of character" ("A Version of Homer that Dares to Match Him Line for Line", New York Times Book Review, 12/10/2017).

As he was writing his book (and as he acknowledged there), he became aware of a similar argument by Bruno Snell, a German philologist, in his book, The Discovery of the Mind (1953).  Snell argued that the characters in Homer do not have any -- well, character, in the modern sense of a personal self.  They don't seem to have minds of their own, and they don't seem to have personalities.  Their actions appeared, to him, to result from divine intervention, rather than any beliefs and desires on their part.  Further, he noted, that Homer did not have words for "mind" or even "body", in our modern sense.  For example, in Homer the word psyche refers not to mind or consciousness, exactly, but to some kind of spirit which departs the body at the time of death. 

"[I]t appears that in the early period the 'character' of an individual is not yet recognized....  There is no denying that the great heroes... are drawn in firm outline and yet the reactions of Achilles, however grand and magnificent, are not explicitly presented in their volitional or intellectual form as character, i.e. as  individual intellect and individual soul" (Snell, 1953, quoted in Knox, 1993, p. 39).

Bernard Knox, in his beautifully titled essay, "The Oldest Dead White European Males" (in his book of the same title, published in 1993; see also another of his essays, "The Human Figure in Homer", from 1991), argued to the contrary, also on philological grounds.  He points out that all the individual characters have names, which individualizes them.  And they also have mental states.  Achilles is full of rage, obviously -- it's the first word in the Iliad.  There are other examples.  For example, Achilles himself makes a big decision: to become a hero with a short life rather than an ordinary man who lives longer.  Moreover, Knox correctly criticizes Snell for making an argument from silence.  Just because Homer does not describe the thoughts and desires of Achilles and the rest, doesn't mean that they didn't have them.  Finally, Knox argues, it's a mistake to take the language of epic poetry as representative of the language of everyday life.  Otherwise, you might conclude that pre-Homeric ship-captains gave sailors their orders in hexameter!  

Still, most of the examples of modern consciousness -- of beliefs and desires leading to action -- come from the Odyssey, and that is Jaynes' point.

More recently, James Kugel, a biblical scholar, has offered a similar argument as Jaynes in the Great Shift (2017).  He points out that at one point, God spoke to people -- think of Moses and the burning bush; now, however, people speak to God, in various forms of prayerWhat Kugel calls "The Great Shift" reflects a change in our understanding of God (as a being "out there", rather than a part of nature), but also a change in human consciousness.  Kugel argues that the premodern mind was "semipermeable" (adopting Charles Taylor's idea that it was "porous") -- meaning that premoderns did not perceive themselves as individuals separate from the natural world, but rather a part of it.  One result was that they heard voices talking to them, instead of thinking to themselves -- Jaynes's essential argument, from a religious as opposed to a psychological perspective.


Psychological Critiques of Jaynes

As far as psychologists, philosophers, and other cognitive scientists are concerned, the most upsetting thing about Jaynes is his insistence that humans were not always conscious.  

Some of this misunderstanding is Jaynes' fault.  He writes about "the bicameral mind", with a right-hemisphere "decision-making part" and a left-hemisphere "follower part", and the implication that, one day, the two hemispheres came together and that is the origin of consciousness.  Of course, the two hemispheres were always together -- there is no reason to think that the corpus callosum suddenly emerged about 1000 BCE to connect them.

And some of this misunderstanding is somewhat forensic in nature.  For example, Daniel Dennett has written approvingly of Jaynes' arguments because, in Dennett's view, they support the idea that consciousness is a social construction.  That it doesn't "really" exist, but rather that it exists only as a figment of our Cartesian imaginations.

But another interpretation of Jaynes is that there was a point in historical time when humans realized that they were conscious -- that they had minds of their own, and that they could control their own minds -- in a way that they didn't really understand that before.  The origin of consciousness, in this view, was much less an invention than a discovery -- a little like Moliere's Dr. Pangloss, who discovered that he had been speaking prose all his life!  

There are certainly precedents to this kind of discovery.  For example, anthropologists often speak of the Neolithic Revolution -- the term was coined by V. Gordon Childe -- that occurred when humans replaced hunting and gathering with agriculture.  That discovery apparently occurred once, at a particular time and place (the Fertile Crescent, in the land known then as Sumer, present-day Iraq), and then spread like wildfire into Europe, Asia, and Africa.  There are, in fact, a number of such "firsts" -- by Samuel Noah Kramer listed 39 of them in his book History Begins at Sumer (1956).  Why couldn't the discovery that we are conscious -- that our mental states represent things other than themselves, and that we can control the contents of our own minds -- have been one of them?

That is, apparently, what happens in infant cognitive development, as the child achieves, and then fleshes out, a theory of mind.  Jaynes wrote his book before there was much talk about the theory of mind (it was published in 1979, and Premack and Woodruff had introduced the concept of "theory of mind" only in 1978).  I can't help but think that, had he known of the concept, he would have not relied so much on bicamerality.  Rather, he might have thought about the origins of consciousness as a cultural achievement -- a point where someone discovered that he was conscious, and told someone else about it, and the idea spread like wildfire.  


Where Did Consciousness Come From?

Again, Jaynes was writing in the early and mid 1970s, before anyone had a concept of the theory of mind (the Premack & Woodruff paper was published in 1978).  But what he's really talking about is the development of a theory of mind in human history. 

As Jaynes (1986) once put it,

All that is most human about us, this consciousness, this artificial space we imagine in other people and in ourselves, this living within our reminiscences, plans, and imaginings, all of this is indeed only 3000 years old.  And that, ladies and gentlemen, is less than 100 generations. And from that I think we can conclude that we are all still very young.


This page last revised 01/08/2024.