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Is there "something it's like" to be asleep?  Certainly, there seems to be "something it's like" to have been asleep, but that's not the same thing.  And there seems to be "something it's like" to be dreamingOr is there?


The Meaning of Dreams

Dreams have probably been of interest as long as people have been conscious -- which is to say, as long as they have distinguished between dreams and ordinary waking life.  Oscar Wilde, the Irish poet, playwright, and general all-round wit, is said to have called "I had a very interesting dream last night" the most frightening sentence in the English language ("Perchance to Dream", a survey of recent popular books on sleep and dreams by Zoe Heller, New Yorker, 12/10/2018).


Dreams in the Ancient World

The ancient Greeks had a whole panoply of gods devoted to sleep and dreams.  First, there was Hypnos, the god of sleep (from which the term hypnosis is derived).  He was attended to by the Oneiroi, triplets who  were the offspring of Nyx, the goddess of the night (at least according to Hesiod's Theogony; according to the Roman Cicero's De Natura Deorum, they were the offspring of Erebus).  Their job is to bring dreams to mortals (and, for that matter, gods) who fall under the spell of Morpheus.  In some accounts, the Oneiroi are the brothers of Hypnos; but Ovid, in the Metamorphoses, says that they are his sons.  Still others say that they were born as a result of parthenogenesis.  The whole thing can get pretty confusing, so don't get hung up on it.  The Greeks had gods for everything.
In Judaism, as in Greece and elsewhere in the Near East, the dreams of kings, priests, and prophets  were considered to be a medium of divine revelation -- but they needed to be interpreted, even though the interpretations themselves were sometimes viewed skeptically. 
Dreams also play a role in the Christian New Testament.

Modern Approaches to Dreams

By "modern" I mean that period of history that begins with the Enlightenment of the 16th-17th centuries. 

Dreams played a special role in the Romantic era of the 19th century, with its emphasis on mysticism, the unconscious as a source of wisdom and inspiration, if not foreknowledge of events.  All of which laid the groundwork for the surge of interest in dreams stimulated by the psychoanalytic theory of Sigmund Freud.


Freud's Interpretation of Dreams

In modern culture, of course, interest in dreams has its roots in Freud's monumental treatise,  The Interpretation of Dreams (1900) -- actually published in 1899, but given a 1900 date to mark the beginning of a new century, not the end of the old one (Freud's  was published in 1899).   The book was written during the period between Breuer and Freud's Studies on Hysteria (of which more later, in the lectures on "Hysteria") and Freud's Three Essays on the Theory of Sexuality (1905).   Along with Psychopathology of Everyday Life, it is one of Freud's best books -- which is not to say that it's scientifically correct.  Only that it has relatively little taint of the theory of infantile sexuality, which is where Freud really went off the deep end.

The Interpretation of Dreams begins by reviewing the scientific literature on dreams available at the turn of the century -- a literature that is surprisingly large, but which Freud found unsatisfactory. For example, it was known that we can remember things in dreams that we cannot remember while awake, and that we often forget our dreams soon after awakening. Moreover, the mental life of the sleeper appeared to be quite different from that of waking consciousness. Dreams were full of rich and vivid sensory images and appear involuntary, while normal thought is deliberate and commonly based on language. These and other observations raised the question of the nature of dreams, and whether they have any adaptive purpose.

The bulk of the book contains Freud's attempt to uncover the meanings of his own dreams by means of the technique of free association.  

I shall demonstrate that there is a psychological technique which makes it possible to interpret dreams, and that on the application of this technique, every dream will reveal itself as a psychological structure, full of significance....

Freud began with "The Dream of Irma's Injection".  Irma was both a family friend and a patient, a woman with symptoms of hysteria. Freud had applied his new psychoanalytic method to her, and she had shown some improvement. However, this strategy and its outcome were criticized by Otto, Freud's friend and junior colleague. Freud resolved to defend himself by documenting her case and submitting his report to Dr. M., their senior colleague, for his evaluation. During this period, Freud had the following dream.

 A large hall -- numerous guests, whom we were receiving. -- Among them was Irma. I at once took her on one side, as though to answer her letter and to reproach her for not having accepted my "solution" yet. I said to her: "If you still get pains, it's really only your fault". She replied: "If you only knew what pains I've got now in my throat and stomach and abdomen -- it's choking me" -- I was alarmed and looked at her. She looked pale and puffy. I thought to myself that after all I must be missing some organic trouble. I took her to the window and looked down her throat, and she showed signs of recalcitrance, like women with artificial dentures. I thought to myself that there was really no need for her to do that. -- She then opened her mouth properly and on the right I found a big white patch; at another place I saw extensive whitish grey scabs upon some remarkable curly structures which were evidently modeled on the turbinal bones of the nose. -- I at once called in Dr. M., and he repeated the examination and confirmed it.... Dr. M. looked quite different from usual; he was very pale, he walked with a limp and his chin was clean-shaven.... My friend Otto was now standing beside her as well, and my friend Leopold was percussing her through her bodice and saying: "she has a dull area low down on the left". He also indicated that a portion of the skin on the left shoulder was infiltrated. (I noticed this, just as he did, in spite of her dress.)... M. said: "There's no doubt it's an infection, but no matter; dysentery will supervene and the toxin will be eliminated." ... We were directly aware, too, of the origin of the infection. Not long before, when she was feeling unwell, my friend Otto had given her an injection of a preparation of propyl, propyls ... propionic acid ... trimethylamin (and I saw before me the formula for this printed in heavy type).... Injections of that sort ought not to be made so thoughtlessly.... And probably the syringe had not been clean.

Freud's interpretation began by identifying certain day residues, aspects of the dream that were clearly related to recent events. Irma, Otto, and Dr. M. are obvious examples. Moreover, Freud and Irma happened to be vacationing at the same resort at the time, and Irma was to be a guest at a forthcoming party. (Most of Freud's patients were drawn from the upper strata of Viennese society, and it was remarkably common for physicians and their patients to move in the same social circles.) Wilhelm Fleiss, one of Freud's friends, had the theory that trimethylamine was a byproduct of sexual activity. Irma was a young widow, and Freud had suggested that her mental illness was caused by problems of a sexual nature. With these and other considerations in mind, the meaning of the dream was quite clear to Freud. Otto, not Freud, was responsible for Irma's continuing illness. His skepticism prevented her from becoming fully involved in her treatment, abreacting, and achieving a complete cure. In the dream, Freud's diagnosis was confirmed not only by the impartial Dr. M., but also by Otto's brother Leopold! Thus, the dream represented Freud's much-desired revenge on his colleague.

 Making the same point, Freud (1900, pp.) reports the following dream by his 19-month-old daughter, Anna, who was later to make her own distinguished contributions to psychoanalysis. The story of Anna's Dream actually gains something in translation, but the reader should imagine the child using the equivalent of German baby-talk.

 My youngest daughter ... had had an attack of vomiting one morning and had consequently been kept without food all day.  During the night after this day of starvation she was heard calling out excitedly in her sleep: 

"Anna Fweud, stwabewwies, wild stwawbewwies, omblet, pudden!" 

At that time she was in the habit of using her own name to express the idea of taking possession of something. The menu included pretty well everything that must have seemed to her to make up a desirable meal.

Freud's analyses of other dreams led him to similar conclusions about the nature and function of dreaming. 


Dreams as Wish-Fulfillments

For Freud, dreams represented wish fulfillment, though in fantasy rather than reality. Often the wish is transparent, as in Freud's dream of Irma and Anna's dream of food. At other times, however, the wish is hidden by distortions, displacements, and symbolic transformations. Therefore, the manifest content of the dream, its surface appearance, must be interpreted to uncover its latent content, or hidden meaning. In such cases, Freud thought, the meaning is hidden because it arouses anxiety. The analysis of dream symbolism, then, suggested that there were other mental forces at work besides those which prevented unpleasant memories from becoming conscious. These additional forces disguised the true meaning and significance of ideas that were conscious.

Latent content is transformed into manifest content by the dream-work, which consists of several elements:

              DreamSymbols.JPG (77985 bytes)Although the wishes being fulfilled in The Dream of Irma's Injection and Anna's Dream are pretty realistic, and the interpretation of them pretty straightforward, sex was already very much on Freud's mind, and so he listed, in Chapter 6, a number of common dream symbols that represent genitalia and the things you can do with them.


Still, it must be remembered that even Freud, somewhere, said that "Sometimes a cigar is just a cigar".  


Dreams as Puns

Another, less well known, Freudian approach to dreams  is based on Freud's theory of humor, which emphasizes the role of puns.

It was this idea that appealed to James Joyce, who was an inveterate punster, and whose novel Finnegans Wake, is made all the more difficult because of its heavy reliance on puns. In Joysprick (1973), Anthony Burgess classified novels into two types. Type A novels have plots, and characters, and some degree of psychological insight into both; Type B novels mostly involve plays on words. Type B novels are exemplified by James Joyce's Finnegans Wake. As Louis Menand writes (in "Silence, Exile, Punning", New Yorker, 07/02/2002):

Joyce was fond of the line in Ovid "Everything changes, nothing is lost". He thought that, from some vast superhuman distance, the people in Ulysses are just like the people in Homer. They are tracing the same patterns, walking through the same roles, struggling to work out the same sets of relations: husband and wife, father and mother, son and daughter -- who will become, in their time, husbands and wives, fathers and mothers.

Finnegans Wake is Joyce's effort to give imaginative expression to this conception of human life. The entire book is made out of portmanteaus and puns.

But I'm loothing them that's here and all I lothe. Loonely in my loneness. For all their faults. I am passing out. O bitter ending! I'll slip away before they're up. They'll never see. Nor know. Nor miss me. And it's old and old it's sad and old it's sad and weary I go back to you, my cold father, my cold mad father, my cold mad feary father, till the near sight of the mere size of him, the moyles and moyles of it, moananoaning, makes me seasilt saltsick and I rush, my only, into your arms.

But Menand notes that there's more to Finnegans Wake than puns:

Finnegans Wake is not a prose poem, which is probably how many people would like to read it. It's a work of realist fiction. It's just that the reality it represents is nighttime reality, the dream life, which Joyce believed required the invention of a new mode of language. Normal syntax is designed for a law-abiding reality, for a reality that is organized temporally, spatially, and causally. In dreams, these laws are suspended, which means that, to represent the dream life, normal syntax has to be suspended, too. And images in dreams can represent two things at once, as when we dream of X and know all the time that it is Y. This is why punning is the language of the night.

Michael Chabon expands on this theme in "What to Make of Finnegans Wake?" (New York Review of Books, 07/12/2012). He notes that, just as Joyce's Ulysses takes place in a single day, Finnegans Wake take place over the course of a single night.

I had already experienced, in those first moments of my encounter with Finnegans Wake, the most reliably dreamlike of its effects: the tantalizing way it both hints at meaning -- deep, important meaning -- and mocks it. Dreams are the sea-Monkeys of consciousness; in the back pages of sleep they promise us teeming submarine palaces but leave us, on waking, with a hermetic residue of freeze-dried dust.


...Finnegans Wake attempts to recreate, by means of an invented language that Joyce derived from English, the flow and the flavor of a single night as it passes within the fitful, sleeping consciousness of a Dublin tavern keeper named Earwicker or possibly Porter.

There is not a whole lot in the way of external action: by comparison to Finnegans Wake, Ulysses is Scaramouche. the sleeper rolls over. He grumbles. He farts. Late in the book, without quite waking, he f----s his wife, who lies asleep beside him. At numerous points, her dream narrative -- along with those of their three children, and of all sleepers, everywhere, busy dreaming in Swahili and Gaelic and Norwegian and even (so lonely!) Volapuk -- seems to intermingle with the protagonist's, all the narratives running together, like rivers, into a single great confluent babel of dreams.

Later in the essay, Chabon explains the structure of the novel to his younger son:

I turned to the last page of the book, to the last broken, stutter-stepping sentence, and showed him how it twists like a Mobius ribbon around to meet that dangling inchworm at the start.

"A way a lone a last a loved a long the riverrun," he read, skipping from the final page to the first, "past eve and Adam's, from swerve of shore to bend of bay, brings us by a commodius vicus of recirculation" -- struggling with it -- "back to Howth Castle & Environs."

His face lit up, at the completion of that circuit, with genuine pleasure. He went back and forth, back and forth, and for a moment the book became a massive flipbook, of two frames' duration. then, looking puzzled, he asked me if James Joyce meant to suggest, by means of this device, that at the end of a night of dreaming, the night began all over again. I told him I guessed that was the general idea.

"I'm glad my dreams aren't like that", he said.

No, I haven't read Finnegans Wake (and I'm saving Ulysses for retirement). But after reading Chabon's essay, I think I'd like to.

The Topographical Theory of the Mind

The Interpretation of Dreams also presents Freud's earliest theory of the mind, called a topographical theory because it maps the mind into several compartments holding various types of mental contents -- Freud drew an analogy to the microscope or telescope, a "compound instrument" composed of a series of lenses through which light must pass from the environment to the eye.

Of course, Freud recognized that we are not simultaneously aware of everything that we know, or that is going on around us. We focus our attention on some things and either filter others out, fail to pick them up, or actively ignore them.

In Freud's early theory, some wishes arouse conflict and anxiety, which leads the System Pcs to censor them, refusing them representation in the System Cs, and relegating them to the System Ucs instead.  During sleep, however, the censor is weakened, permitting the forbidden wish to be expressed in consciousness.  But the censor is not weakened entirely, with the result that the wishes have to be expressed, and fulfilled, in disguised, symbolic form.  

Unfortunately, as both J.-P. Sartre (in Being and Nothingness) and Noam Chomsky (1980) has noted, some confusion has been caused by Freud's inconsistent definitions of these terms. At times Freud asserted that material in the System Ucs was, in principle, inaccessible to conscious awareness and control. At other times he conceded that such material might be accessible under certain special conditions. However, the distinction between the System Pcs and System Ucs on the grounds of accessibility is clearly stated in The Interpretation of Dreams. There Freud describes the System Ucs as containing information which cannot be brought into phenomenal awareness and placed under voluntary control.  Still, Freud was inconsistent on the relation between the System Pcs and the System Cs: contents in the System Pcs are supposed to be available to the System Cs, but Freud also wrote that there was a barrier of censorship between Pcs and Cs.

 The movement of mental contents through the three systems follows lines of cathexis (attention) and anticathexis (avoidance or suppression). Mental contents can be transferred between Pcs and Cs at will: cathexis activates some content and brings it to mind. Cathecting something new deactivates the former contents of Cs and allows it to return to a dormant state. However, the erection of an anticathexis between Ucs and Pcs creates an effective barrier to consciousness, so that material held in Ucs cannot be brought to mind by an act of will.

 Freud's topographical theory was almost his last gasp as a neurologist -- his very last was an unwillingly written revision of his 1897 book on cerebral palsy.  It seems clear that in his earliest conception, the systems Ucs, Pcs, and Cs were construed as discrete locations in the brain where corresponding ideas were stored. Later, the topographical theory took the form of a flowchart, without much implication that the systems had separate physical representations in the biological structures of the mind. Finally, the terms conscious, preconscious, and unconscious dropped to the status of descriptive labels identifying a property of mental contents -- whether they were accessible to consciousness or not. 


The Functional Theory of the Mind

This evolutionary trend laid the groundwork for Freud's final theory, announced in The Ego and the Id (1923). This theory is called functional (as opposed to topographical) because it classifies mental contents according to what they do, and the principles according to which they operate, rather than where they are.  This is where the "Monsters from the Id" come from: wishes arising from the Id conflict with either external reality (represented by the Ego) or social demands (represented by the Ego) and are repressed -- only to reappear in disguised, symbolic forms in dreams, speech errors and other parapraxes, and neurotic symptoms.   In the functional theory, dreams are generated by the Id, and escape censorship by the Ego and Superego.  But not completely: our dreams are represented in disguise, symbolically.  Only in psychosis are our wishes fully manifested in consciousness.  At least, that was Freud's view.  But remember, Freud got every detail wrong.  so don't take his theory of psychosis too seriously.


REM and Dreaming Revisited

Freud's theories of dream-interpretation shaped 20th-century culture in profound ways, but they haven't held up scientifically.  In particular, as we shall see, the discovery of the association between dreams gave dream-theorizing a new starting-point.  

011Recall.jpg (38575
            bytes)Recall that Aserinsky and Kleitman (1953) first observed the cyclical shift from SREM to REM, with bursts of REM, lasting 10-20 minutes, occurring approximately every 90 minutes.  On Aserinsky's hunch, they awakened sleeping subjects, and asked them a simple question: "Were you dreaming?".  The result was a much higher frequency of dream reports during Stage REM (74% of awakenings) than Stage NREM (only 17% awakenings). So, Aserinsky and Kleitman concluded that dreams do not occur throughout sleep (as had been suggested by Freud, for example), but are largely confined to REM. 

The early findings of Aserinsky and Kleitman were subsequently replicated by a number of other laboratories, and so the traditional conclusion has been that dreams occur in Stage REM.  However, it's not completely clear that dreams are solely a phenomenon of REM.

A lot depends on how we define the "dream".  Snyder (1970) offered the following characteristics of dreams:

Defined in this way, dreams do occur more frequently in REM than in NREM.  But they're not completely absent from NREM, either.

And further, a lot depends on how we ask the question: 
012Mentation.jpg (40405
        bytes)This is just what David Foulkes (1962) discovered when he analyzed results from a new REM-awakening study.  


In another, more detailed study, Foulkes and Schmidt (1983) obtained a similar result:

NREM dreams may not be as elaborate as REM dreams: They more closely resemble conventional thinking or daydreaming.  Whatever imagery they possess is likely fleeting, and not particularly vivid, and there is little sequential development.  Nevertheless, this analysis makes it clear that there is mental activity during NREM as well as REM -- including full-fledged dreams.  This may mean trouble for theories that assume a unique association between Stage REM and dreaming.

If REM and NEM dreaming differs with respect to REM, what do these two dream-states have in common?  A recent study by Francesca Scilari, Giulio Tononi, and their colleagues (Nature Neuroscience, 2016) followed the general procedure of Aserinsky and Kleitman, awakening subjects at various points of sleep and asking them whether they had been dreaming.  As in Foulkes's study, subjects reported "dreaming" in both REM and NREM sleep.  Regardless of EOG activity, high-density EEG (i.e., EEG recorded from a large number of scalp electrodes) revealed that dreaming was associated with high-frequency activity in the posterior region of cerebral cortex, near the primary visual area of the brain. 

The controversy over dreaming in NREM sleep raises questions about the PCI index of consciousness discussed in the lectures on Mind and Body.  Recall that Casarotto et al. (2016) performed a "benchmarking" study which established a value of PCI* = .31 for distinguishing between subjects who are conscious and those who are not.  As part of their study, these investigators looked at PCI in healthy subjects in various stages of sleep.  While subjects in REM sleep showed median PCImax values greater than the PCI* threshold value of .31, and approaching those of subjects who were awake and fully conscious (.48 vs. .53), subjects in NREM sleep had considerably lower median values for PCImax.  This is taken as support for the validity of the PCI* index of consciousness, but there are some problems with this conclusion.

These considerations remind us of James's assertion that consciousness is always about something.  We're not conscious in the abstract.  We're conscious of objects and events in the world, memories of the past, thoughts, images, etc.  PCI* may measure the flow of activation in and around the thalamocortical system, but it's not at all clear that it's actually measuring consciousness.


Lucid Dreaming

A special form of dreaming is the lucid dream (Green, 1968; LaBerge, 1985, 1990), in which the dreamer is aware that he or she is dreaming.  Lucid dreamers are able to remember the events of waking life while dreaming, although they have no on-line awareness of the real external world in which they are sleeping.  Also, they appear to be able to control the plot of the dream while remaining asleep.

Lucid dreaming is relatively rare, but most people have had at least one lucid dream, and it has been estimated that about 20% of the population dream lucidly at least once per month.

Lucid dreams were first described by Eeden (1913), and described as integral to the Senoi culture of Malaya (Stewart, 1969), but were not taken seriously until recently.  In fact, the philosopher Normal Malcolm (1959) dismissed them as impossible or absurd.  

Early sleep researchers, such as Foulkes (1974) and Hartmann (1975), took lucid dreaming more seriously, but noted that it tended to occur during the second half of the night.  For this reason, they attributed the phenomenon to transitory arousal during stage REM.  That is, lucid dreamers realize that they're dreaming because they're actually awake.  

In pioneering research, David LaBerge (1981, 1985, 1990) instructed unselected subjects to signal when they experienced the onset of a dream by making a specific series of eye movements, or by clenching their fists.  LaBerge discovered that a minority of subjects could do this.  LaBerge also confirmed that lucid dreaming was more likely to occur during the second half of the night.  However, he determined that lucid dreaming occurred even when subjects' EEG was free of alpha activity.  Because the absence of alpha is the physiological definition of sleep, this indicates that lucid dreaming was not an artifact of transitory arousal.  

Eye Movements and the Isolated Forearm Technique

At first blush, the fist-clenching instruction would seem to be inconsistent with the definition of Stage REM as involving paralysis of the skeletal musculature.  Still, this paralysis does not extend to the eyes and other parts of the head and face that are supplied by the III and IV cranial nerves -- which is why you can get REMs during Stage REM.  So, while communicating a lucid dream by fist-clenching might indeed mean that the person is actually awake, at least in principle such a message could be sent by eye movements.  For this reason, eye movements have been employed in subsequent research.

As discussed in the lectures on Anesthesia and Coma, the isolated forearm technique (IFT) can be used to determine whether supposedly anesthetized patients are actually aware of what is going on around them.

Inspired by LaBerge's studies of lucid dreaming, Henry Bennett has proposed that something similar could be done with eye signals in anesthesia.  The muscle relaxants employed in balanced anesthesia affect the functioning of the spinal nerves, but do not appear to affect the cranial nerves in the same way.  Therefore, it is possible -- at least in principle -- that anesthetized subjects could communicate any awareness through eye movements.  

Subsequently, LaBerge developed the Method of Lucid Dream Induction (MILD), by which people can be taught to dream lucidly.  In physiological studies, LaBerge documented an increase in lucid dreaming among subjects who were taught the MILD technique, again in the absence of EEG alpha activity.  LaBerge now offers occasional workshops, in lovely resort areas, in which people pay a fee to be taught the MILD technique.

Further physiological research (LaBerge et al., 1986) found that lucid dreams were accompanied by an increased density of REM activity, increased heart and respiration rate, and increased fluctuations in galvanic skin potential -- all indications of increased physiological arousal.

On the psychological side, LaBerge has suggested that lucid dreams occur when a bizarre dream event -- say, a dragon riding a bicycle down the Champs-Elysees -- stimulates reflection on the dream, and the consequent realization that one must be dreaming.  Alternatively, it is possible that subjects are awakened from the dream, realize that they are dreaming at that point, fall back asleep after this transient awakening, and then move directly back into REM without any of the NREM activity that would normally intervene, and thus enter directly into the dream.

There are lots of books and workshops offering to train people to have lucid dreams, but it's not clear that any of them accomplish anything except lining the pockets of the people who promote them (see "So You Want to Have a Lucid Dream?" by Dorie Chevlen, New York Times, 04/01/2021).

Even with training, lucid dreaming is rare.  Most of us don't do it very often, and there aren't too many who do it frequently.  Nevertheless, lucid dreams open up the possibility for re-invigorating psychological research on dreams.  Previously, we had no independent access to dream contents.  But with LaBerge's signaling system, there is at least the possibility that subjects could report on their dreams as they occur, instead of retrospectively.  

Senoi Dream Theory

LaBerge's work on lucid dreaming was largely inspired by a description by Kilton Stewart of practices he observed among the Senoi, an aboriginal tribe who live in the jungle highlands of Malaysia.  And Stewart's writings on the subject, laid the basis for the promotion of dream-work as a technique for self-help psychotherapy -- for example, Ann Faraday's Dream Power (1972) and Patricia Garfield's Creative Dreaming (1974) -- interest in which was renewed by LaBerge's research.

LaBerge himself now gives workshops, mostly in seaside resorts, in which people enroll to learn how to dream lucidly.  A journalistic account of one of these workshops, not entirely friendly, was published in the New York Times Magazine ("Inward Bound" by Lawrence Osborne, 07/18/04).

In the meantime, Senoi dream theory has now been pretty much discredited.  There is a people called the Senoi, and they dream, of course, but they don't practice anything even remotely resembling Senoi Dream Theory, and apparently never did.  Stewart's claims were not a hoax, but they did constitute a highly romantic tale that was eagerly taken up by the "human potentials" movement that emerged in the 1960s and 1970s.  The whole sad story is told by William Domhoff, a psychologist at UC Santa Cruz, in his book The Mystique of Dreams (1985), and a 2003 update available on Domhoff's website.  

Link to Senoi Dream Theory: Myth, Scientific Method, and the Dreamwork Movement by G. William Domhoff (2003).


Bilingual Dreaming

It's been said that you really know another language when you begin to dream in it -- an idea that forms the basis for such "language-learning memoirs" as Dreaming in Chinese by Deborah Fallows and Dreaming in Hindi by Katherine Russell Rich (to my knowledge, there is no Dreaming in English yet).  It's an interesting idea, and raises the question of how bilinguals dream.  Foulkes and his colleagues (1993) awakened German-English bilinguals (half native English speakers, half native German) during REM, and asked them if they were thinking or speaking about anything in the dream, and if so what language was used.  All the dreamers reported that they dreamt in both languages, but the most powerful determinant of the language of dreams was the language in which the pre-sleep interview had taken place.

What We Dream About

With Azerinsky and Kleitman's discovery of the connection between REM and dreaming, it seemed that the study of dreams might be put on a firm empirical basis. At last, we had an objective index of when a subject was dreaming.  A&K simply asked their subjects whether they dreamed.  It fell to others to ask them what they dreamed about.

The Hall & Van De Castle Study

It took a while but Calvin S. Hall (who taught at UC Santa Cruz) and Robert L. Van de Castle (1966) conducted an extensive content analysis of 1000 dreams reported by a sample of college students, 5 dreams selected more or less arbitrarily from reports by 100 men and 100 women.  Actually, the dreams had been collected in 1947-1950, before A&K's study.  And they were not based on REM-awakenings.  Rather, Hall had asked the students to keep dream diaries as part of a class project (the identities of the students had been removed prior to analysis).  They then coded the dreams on a number of variables

Why "Freudian themes"?  Well, to begin with, psychodynamic theory was by any standard the dominant theory of personality at the time, and psychoanalysis was the dominant mode of psychotherapy.  So Freud was in the air.  Hall was deeply interested in psychoanalysis, and wrote a popular Primer of Freudian Psychology (1954) as well as a corresponding Primer of Jungian Psychology (1973, with Vernon Nordby).  

H&VdC showed that various aspects of dream reports could be coded reliably, setting the stage for further studies relating dream content to various aspects of personality -- and, in general, tryng to discover the meaning of dreams.  In a series of case studies, for example, Hall and others were able to perform blind diagnoses of personality, given just the barest demographic information and a sample of the individual's dreams.  Other studies traced the development of dreams throughout the lifespan, the influence of trauma on dreams, and the like.  Van de Castle reviewed much of this research in Our Dreaming Mind (1994), which begins with an excellent historical overview of theories of dreams from ancient times to the 20th century.was a selection of the Book-of-the-Month Club.

Despite what might have been the Freudian inspiration for their research, the general conclusion that arises from the H&VdC study is that the typical dream is a more or less coherent account of a more-or-less realistic situation, in which more-or-less ordinary characters are engaged in more-or-less ordinary activities.  One of these features, coherence becomes an important element in the debate over the meaning and origins of dreams, as we shall see.

Stimulus Incorporation in Dreams

In sleep, we appear to be shut off from the outside world -- otherwise, we'd be awake, right?  But we are not entirely shut off. We awaken in the morning to the sound of our alarm clock or clock radio, for example.  And we're awakened in the night by the siren of a passing police car, or by the cries of an infant in the next room.  Even if we don't awaken, some of these environmental stimuli can be incorporated into our dreams.

A classic example is the guillotine dream of Alfred Maury (1817-1892) , a French physician who wrote Le Sommeil et les Reves ("Sleep and Dreams", 1861, revised 1878), a treatise on dreams that influenced Freud (he was also the first to describe the hypnagogic hallucinations we often experience while falling asleep).  One night, Maury dreamed that he was on trial during the French Revolution and sentenced to death.  He was led to the guillotine, and felt the blade sever his head from his body -- at which point he awakened to find that the headboard of his bed had fallen, and was resting on the back of his neck.  From this, Maury concluded that his dream had occurred instantaneously in response to the tactile sensation of the headboard on his neck.  Or, as we might put it today, the entire dream was a reconstruction, in memory, based on that sensation. 

Later, Maury arranged for an assistant to present him with various stimuli while he was sleeping. 

You get the idea.  Similar experiments were conducted by others, with similar results. 

Other investigators studied the effects of pre-sleep stimulation on dreams.  Perhaps the most famous of these was conducted by Otto Pśtzl (1877-1962), a neurologist and psychiatrist who was influenced by Freud's psychoanalytic theory of the unconscious, as part of his research on subliminal perception (Psychological Issues, 1960).  Pśtzl (1960) used a tachistoscope (no computer screens in those days) to show pictures to a group of subjects. The images were displayed for only 10 milliseconds, without a mask, thus permitting only the briefest glimpse of their contents.  When asked to report (or draw) the contents of the pictures,  the subjects typically omitted some details.  Yet Pśtzl reported that those omitted details, or symbolic representations of them, often appeared in the subjects' dreams.  For example, a subject who was shown a photograph of an ancient temple omitted a standing human figure from his description of the picture, but a similar figure appeared in a dream that night.  Similar findings were obtained when Pśtzl presented the images for a longer period of time in the periphery of the subjects' visual field.  This Pśtzl phenomenon interested Freud, and he remarked on it in a a later edition of the Interpretation of Dreams.  Pśtzlalso formulated a law of exclusion by which features of the stimulus that were consciously perceived in the picture were not represented in the subject's dreams.

But of course, these experiments were conducted long before we knew anything about the association between dreams and REM sleep, and so we don't know whether the stimuli were applied during periods of REM or NREM.  

Pśtzl's findings were confirmed by Fisher (1954, 1956, 1960a, 1960b), Shevrin and Luborsky (1958, 1961; Shevrin & Fisher, 1967), and others.  For example, Shevrin and Fisher (1967) gave subjects a single brief (6/1000 second) tachistoscopic presentations of a "rebus" puzzle, in which a picture (e.g., of a pen touching a knee) represents a word or phrase (e.g., penny).  The subjects then slept in the laboratory, and gave dream reports following REM and NREM awakening.  The dream reports were then scored for "rebus" associations (e.g., the word penny, or related concepts such as money and round) and "conceptual" associations (e.g., paper or bone).  Compared to a waking control condition, rebus associations were found to occur more frequently in REM awakenings, while conceptual associations were more frequent in NREM awakenings.

Pśtzl, Shevrin, and Fisher employed subliminal pre-sleep stimuli in view of the psychoanalytic idea that dreams are expressions of unconscous ideas, feelings, and wishes (actually, Poetzl was initially interested in this problem from a neurological standpoint, but he (and Freud) quickly saw the implications for psychoanalysis).  But what about supraliminal stimulation, during sleep?

The classic experiment in this case is one by Dement and Wolpert (1958), which was one of the first studies, after the discovery of the REM-dream connection, to actually study the content of dreams.  It was also a very early publication by William Dement, who trained (and eprformed this study) in the Chicago laboratory of Nathaniel Kleitman, and who went on to found the prominent and extremely productive sleep laboratory at Stanford.  Dement's little book, Some Must Watch While Some Must Sleep, originally written for the Stanforrd Alumni Association, remains an excellent introduction to sleep research.  It's also beautifully illustrated with drawings by Pablo Picasso!  Anyway, here's what they found:

In a provocative variant on subliminal advertising, as discussed in the lectures on Implicit Cognition, some advertisers (and some sleep researchers, who might be eligible for some nice consulting fees), have proposed that advertisements could be presented to subjects during REM sleep -- at time during which, so it is claimed, people are particularly vulnerable to suggestion (Carr et al., Con. & Cog, 2020).  Adam Haar Horowitz, a sleep researcher at the MIT Media Lab, has invented a device, called Dormio, that monitors a subject's passage through the various stages of sleep, without requiring the subject to be attached to an EEG, and presents audio cues that can stimulate incubation effects in problem-solving.  And if auditory cues presented during REM can help people solve problems when they are awake -- maybe, just maybe, they can influence consumer behavior as well (see "Advertisers Could Come for Your Dreams, Researchers Warn" by Sofie Moutinho, Science, 06/25/2021). 

Memory for Dreams

Almost by definition, the sleeper, once awake, remembers little or nothing that transpired in the external environment while he was asleep.  But what about events in the internal environment, and especially the dreams that are played out, at least during REM sleep, on the stage of the mind's eye and ear?  

One of the greatest puzzles of sleep concerns memory for dreams.  We probably have, on average, at least 4-5 dreams every night, but we typically remember, at best, only one of these. The contrast between the large number of dreams that occur in the night, and the small number of dreams remembered in the morning, raises the question of what accounts for the remembering and forgetting of dreams.

Freud, of course, explained our poor memory for dreams through repression: all that gets through the repressive barrier are the very distorted symbolic contents -- and, as even Freud realized, not very much of that.  


Personality Correlates of Dream Recall

There are no individual differences in dream recall following REM awakenings -- pretty much everyone remembers a dream if they're awakened during REM.  But there are substantial and stable individual differences apparent in sleep diaries and self-report questionnaires, which reflect memory for dreams upon spontaneous awakenings, typically in the morning, and typically after a full night's sleep. 

Dream recall, so measured, is essentially unrelated to the major personality traits, such as the "Big Five" of neuroticism, extraversion, agreeableness, conscientiousness, and openness to experience (Cohen, 1974, 1976, 1979; Koulack & Goodenough, 1976).

For example, Cory et al. (1975) classified subjects as dream recallers or non-recallers, based on their responses to both retrospective questionnaires and the entries in a 12-night dream diary.  Frequency of dream recall was essentially uncorrelated with questionnaire measures of such personality traits as anxiety, repression-sensitization, or locus of control.

A partial exception to this conclusion, not considered by Cory et al., may be absorption, a component of openness.  Subjects who score higher on scales measuring "receptivity to inner life" tend to recall dreams more frequently than those who score low.  Such individuals are highly introspective, aware of their feelings and other internal states; they are able to express their emotions freely; and they are not obsessively bound to reality demands.  But even these correlations are relatively week.


Dream Recall and Memory Consolidation

In all likelihood, the most important determinants of dream recall probably lie in cognitive processes, rather than personality structures.  In fact, the study by Cory et al. (1975) showed nonsignificant correlations between dream recall and measures of anxiety, repression-sensitization, and locus of control, but significant correlations with measures of visual short- and long-term memory, and incidental visual memory. Dream recall in the morning was also correlated with the number of spontaneous awakenings during the night -- which is a big clue as to why we remember as few dreams as we do.

Assuming that dreams are staged in primary (short-term) memory, the conventional hypothesis is that REM awakenings permit direct on-line readout of the dream from primary (short-term) memory, while morning dream reports require retrieval of the dream from secondary (or long-term) memory. Given the stage analysis of memory, dream-recall failure (just like any other memory failure) can be attributed to failures of encoding, storage, and/or retrieval, alone or in combination.

CohenMacNeilage.JPG (49926 bytes)Cohen & MacNeilage (1974) found that dream recallers (measured by self-report) tended -- when brought into the laboratory -- to awaken out of REM, while nonrecallers tended to awaken out of NREM.



043CohenActivity.jpg (48210 bytes)Cohen & Wolfe (1973) found that subjects who lay quietly in bed for 90 sec were more likely to remember a dream than those who telephoned for weather information immediately upon awakening.  Certainly,  the telephone call essentially prevented the subject from rehearsing the dream, and thus encoding it in long-term memory.  In addition, it seems likely that the act of making the call effectively displaced the dream from short-term or working memory. 

Experimental research shows that abrupt arousals from sleep yield greater dream recall than gradual arousals, which afford more opportunity for traces of the dream to fade from primary memory. Similarly, distraction after awakening reduces dream recall, presumably by displacing traces of the dream from primary memory. Dreams are better remembered if they are accompanied by high levels of physiological arousal, suggesting that salience can overcome interference effects. Dream recall is probably best if the sleeper awakens quickly, and then lies quietly in bed.

Transient awakenings out of REM during the night, and a final awakening out of REM in the morning, will make many dreams available in memory. But, typically, very few of these dreams are accessible to morning recall -- probably because the sleeper returns to sleep quickly, before he can engage in the elaborative and organizational activity required to encode items in long-term memory. 

044GoodenoughOnLine.jpg (36096 bytes) A study by Goodenough et al. (1974) collected dream reports "on the spot" from REM awakenings, and again in the morning, over 4 nights of sleep. Somewhat paradoxically, subjects who recalled many dreams during REM awakenings recalled fewer dreams in the morning, compared to subjects who recalled relatively few dreams "on the spot". This apparent paradox may be an illustration of the familiar "fan effect" in memory: the more knowledge you have about a subject, the harder it is to retrieve any particular item of information.

Goodenough et al. (1974) also found that, of the dreams reported "on the spot", those recalled again in the morning tended to be more affect laden, and associated with higher physiological arousal, than those which were forgotten. This seems to illustrate the role of salience in overcoming forgetting.

045PortnoffStudies.jpg (54977 bytes)Goodenough  et al. (1974) also found that morning memory -- whether measured by recall or recognition -- was better for subjects who were kept awake (by a simple psychomotor task) after their "on the spot" reports, compared to those who were allowed to fall immediately back to sleep. This seems to illustrate the role of post-dream arousal in encoding memories for dreams.


046PortnoffSet.jpg (58614 bytes) In addition, those who had a mental set to perceive the task as important had better memory than those who perceived the task as a mere game.  



Dream Recall and Repression

Although their work focused on the effect of cognitive factors such as interference on dream recall, Goodenough and his colleagues also performed some studies inspired by Freudian dream theory -- according to which, memory for dreams is poor because dreams contain threatening content that is repressed.   In their studies, Goodenough et al. (1974) defined "repression" generically as the tendency to forget the disagreeable.  They manipulated pre-sleep stress levels by showing their subjects stressful or neutral films before allowing them to sleep. On two nights, one group of subjects viewed neutral travelogues of London of the American West; another group viewed stressful films depicting either childbirth or an aboriginal rite of male circumcision (the famous "Subincision" film, which in the 1960s and 1970s was to college students what "Signal 30" was to high-school driver's education classes).  Subjects were then awakened during REM periods, to get an "on-line" assessment of the dream, and then were tested for their memory in the morning.

GoodenoughRecall.jpg (51943 bytes)But GoodenoughAffect.jpg (49236 bytes)it was all for naught.  There was no difference between the two groups conditions in dream recall "on the spot", nor in the number of dreams remembered in the morning.  Nor, for that matter, was there any difference in the emotional valence of dreams that were remembered or forgotten in the morning.  If anything, those that were remembered in the morning had higher levels of hostility and anxiety than those that were forgotten.

Thus, pre-sleep stress doesn't substantially reduce morning dream reports, or increase the number of contentless dream reports (where the subject remembers having dreamed, but doesn't remember what the dream was about).  Moreover, morning recall does not seem to favor dreams with positive (or less negative) affect.


Is Memory for Dreams State-Dependent?

As with sleep learning and sleep suggestion, at least theoretically, it is possible that dreams are encoded in long-term memory, but that memory for dreams is state-dependent -- which is to say, we can remember dreams, but only when we're asleep, and in REM.  Certainly, sleeping and waking are markedly different physiological states.  Unfortunately, this hypothesis is, for all intents and purposes, untestable -- for the simple reason that we have no way of interrogating subjects while they're asleep. 

Maybe this problem can be solved with lucid dreamers -- assuming that a way can be found to communicate what they're dreaming, not just that they're dreaming.

How to Remember Your Dreams

by Jaime Lowe (New York Times Magazine, 01/29/2017)

People who are frustrated by how little they can remember from their dreams — or who claim not to dream at all — tend to have similar sleep patterns, according to Robert Stickgold, an associate professor of psychiatry at Harvard Medical School who specializes in sleep and cognition. The dream-deprived nod off quickly, sleep soundly and emerge from sleep fully awake. So before going to bed, drink three full glasses of water — not beer or wine, because they suppress R.E.M. sleep — which will force you to get up and go to the bathroom. “Middle-of-the-night awakenings are frequently accompanied by dream recall,” Stickgold says. “In addition, many people will notice hypnagogic dreams, or those brief dreams that occur as one is falling asleep.”

Stickgold also recommends repeating the phrase “I’m going to remember my dreams” three times before you drift off to sleep. And keep a notebook and pen by your bed. Both preparations establish recall as a priority. “When you lie in bed, all the things rush through from the day,” Stickgold says. “Evolutionarily, that is a period when your brain is trying to figure out what to work on when you’re asleep. All of that is going on when you’re asleep, and pre-sleep is like a to-do list. By putting ‘remembering your dreams’ on your to-do list, you might remember.”

On waking up, don’t open your eyes, don’t move, don’t say a thing — any sensory perception or movement tends to wipe out memories of a dream. “If you roll over and say to your spouse that you just had the coolest dream, you’re going to lose it,” Stickgold says. “Stay half-asleep and replay what you remember in your mind. As you replay it while awake, it gets stored differently, and now you’ve got it. A whole other chunk might even pop into your mind.” Lie there for a few minutes to sink back into the dream, to gather more and more detail. For two weeks, tell yourself to remember your dreams every night and morning. After such a regimen, Stickgold says, “I would predict that 80 percent of people who initially said they never dream would say they do now.”


The Physiology of the Dream State

The distinction between REM and NREM mentation raises the question of what it is about REM that causes dreams to occur. There have been lots of perfectly reasonable hypotheses.

Note, however, that in these accounts, the focus is on REM as a physiological state, in which the dreams themselves are of no particular importance -- they are, essentially, epiphenomenal.  The most popular current theory of REM and dreaming picks up on this point.


The AIM Model of Dreaming 

Hobson and McCarley (1977) proposed an activation-synthesis theory of dreams which assumes a cyclic activation of the cerebral cortex, under the control of a biological clock.  This activation, in turn, results in eye movements (and feedback from them), motor commands (whose execution is blocked by muscle paralysis), vestibular activity (giving rise to sensations of movement), and ANS arousal (emotionality).  Imagery related to this physiological activation is then synthesized by higher cortical centers into the best possible story that can make use of these images, thus forming a dream.  Under this theory, dreams are essentially random and meaningless, their contents depending simply on whatever neural networks happen to be activated at the time, and do not bear any psychological interpretation.  Certainly they do not warrant any Freudian or neo-Freudian interpretation in terms of deep symbolic meanings.

One key to understanding this process is the notion of PGO waves -- bursts of neural activity that have their origin in the pons, stimulate activity in the lateral geniculate nucleus of the thalamus, and thence activate neural networks in the visual areas of the occipital cortex.  Michel Jouvet, a French sleep researcher, recording from microelectrodes implanted in the brains of cats, observed this pattern of activity immediately preceding the onset of Stage REM sleep (Jouvet et al., 1959); they were named "PGO waves" by Brooks and Bizzi (1963).  These waves, in theory, are responsible both for rapid eye movements and the visual imagery commonly experienced in the dreams that co-occur with REMs.  But this is just the beginning!

More  recently Hobson (1990, 1995, 1999, 2000) has modified the activation-synthesis theory and presented what he now calls the AIM model of dreams, which (in Hobson's view, at least) constitutes "an integrative theory of mind-brain states" at both the physiological and psychological levels of analysis.  AIM stands for Activation, Input Source, and Modulation.


Activation: as in the original activation-synthesis model, cortical activation by the reticular activation system, measured by the rate of neural firing in the brainstem, controls the organism's level of alertness.

Physiologically, in REM sleep activity in the pontine tegmentum activates the reticular formation and the cholinergic system, and sets up the PGO waves.  The latter, in turn, activate the amygdala and the paralimbic cortex, resulting in increased emotionality and also access to long-term memory; activates the operculum in the parietal lobe, increasing visual imagery; and deactivates the prefrontal cortex, resulting in decreases in volition, insight and judgment, and working memory.

Psychologically, increased cortical activation (think of those PGO waves) is associated with increased arousal and alertness, as well as increases in the length, intensity, and complexity of mental activity -- reflecting, in turn, increases in the rate at which information can be processed.   

Input Source: by virtue of input-output gating of sensory and motor channels, the source of input shifts between the external and internal environment.

Physiologically, in REM sleep blocking of pontine gateways diminishes motor outputs, making overt behavior impossible, and sensory inputs, making information about the real world unavailable.  At the same time, PGO activity reaching the occipital cortex generates "fictive" visual and motor activity.

Psychologically, changes in input source alter the source of the information processed by virtue of increased activation -- from perception (the external environment) or from memory (the internal environment).  Also, changes in output activity determine whether information-processing will result in "exteroeffective" activity -- that is, in overt behavior directed toward the external environment.  

Modulation: a shift in neuromodulatory balance between aminergic neurons (e.g., those that use norepinephrine and serotonin as neurotransmitters) and cholinergic neurons (e.g., those that use acetylcholine) controls the amount of attention devoted to information processing.

Physiologically, in REM sleep activity in the pons deactivates aminergic neurons and activates while cholinergic neurons.  This increases activity in the thalamus, basal forebrain, and amygdala, all of which are cholinergically modulated; and decreases access to recent memory and orientation to time, place, and person, all of which are the products of aminergic systems.

Psychologically, low levels of aminergic activity diminish attention and complex information processing.

Actually, Hobson (2001) describes a number of different neuromodulatory systems in the brain -- each arising from different structures in the midbrain or hindbrain, and each involving a different neurotransmitter.

In the noradrenergic neuromodulatory system (NMS), aminergic neurons in the locus coeruleus of the pons synthesize norepinephrine (NE).  They project to the spinal cord, brainstem, and cerebellum, but also to the thalamus, limbic system, and cerebral cortex.

In the seratonergic NMS, another set of aminergic neurons, located in the raphe nuclei of the pons, synthesize serotonin (5-HT).  They project to the same destinations as do the neurons of the noradrenergic NMS.
In the acetylcholine NMS, cholinergic neurons in the pons and the basal forebrain synthesize acetylcholine (ACh).  They project to the thalamus, the limbic system, the cerebral cortex, and elsewhere.
Although the aminergic and cholinergic NMSs are critical for sleep and dreams (according to the AIM model, anyway), there are other NMSs in the nervous system.  For example, Hobson has described a dopaminergic NMS, which synthesizes dopamine.  Dopaminergic neurons in the midbrain project to the limbic system and cerebral cortex, as well as to the extra-pyramidal motor system.  Although not important for sleep and dreams (again, according to the AIM model), they are important for other altered states of consciousness, including those produced by psychedelic drugs such as LSD.

Note that synthesis is no longer part of the AIM model.  Synthesis still occurs, but Hobson is more interested in the process that generates dreams, and that gives REM dreams characteristics that are different from NREM mentation, and from waking thought.

Within this three-dimensional AIM State-Space, Hobson has identified three distinct states of consciousness:

Waking, in which the organism is alert and attentive to information arising from the external environment.  Activation is high, resulting in a state of arousal and mental alertness.  Input-output gating allows the brain to receive sensory inputs from the external environment, and to generate motor activities that translate into actual overt behavior.  

NREM sleep, in which the organism is neither alert nor attentive.  Activation is reduced, which is what diminishes arousal, alertness, and attentiveness.  Input-output gating is in a middle position, allowing some sensory and motor activity: sleepwalking and sleep-talking are possible, and the sleeptalker can respond to bed-mates who try to converse with him.  Modulation is more balanced between aminergic and cholinergic activity, so information-processing is not too elaborate, and there's not much memory for what goes on.  

REM sleep, in which the organism is alert but attentive to information arising from the internal environment.  The consequence of REM modulation are (1) high levels of nervous system activation, generating essentially random imagery from memory; (2) little sensory input from, and no motor output to, the external environment; poor memory for this imagery on awakening, because of the low levels of aminergic activity.  Thus, the AIM model explains why dreams occur, and why dreams and other events of sleep are poorly remembered.

During the night, the sleeper's brain cycles continuously through this space, producing the 90-minute cycle of waking and sleeping, four to five times a night, and consequent mental activity.
AminergCholinerg.jpg (54611 bytes) Here's another depiction of the cycle.  Shifts to high levels of cortical activation result in lots of mental activity.  Shifts between external and internal inputs determine whether that mental activity is dominated by perception or by memory, and shifts between external and internal outputs determine whether that mental activity will translate into actual behavior.  Shifts between aminergic and cholinergic activity determine whether, and to what extent, the mental activity will be remembered later -- regardless of where its source lies.  
Hobson has also used this same AIM state-space to explain the effects of various psychoactive drugs, such as tranquilizers, stimulants, and various hallucinogens, on both the brain activity and its associated mental life.  I'll have more to say about this in the lectures on "Psychedelic Drugs", if I ever actually prepare them. 


The AIM Theory in Premodern Europe

In 2009, the Folger Shakespeare Library, in Washington, D.C., mounted To Sleep, Perchance to Dream, an exhibit on sleep and dreams in Shakespeare's time.  Among many interesting items is a book by Thomas Nash (1567-1601), an English writer, entitled Terrors of the Night (1594), in which Nash offers a very modern theory of the meaning of dreams:

"A dream is nothing else but a bubbling scum or froth of the fancy, which the day hath left undigested".

Link to the exhibit website: http://www.folger.edu/woSummary.cfm?woid=454.


Solms' Critique

The activation-synthesis model, and more recently Hobson's AIM model, have been very popular in neuroscientific circles -- in part because Hobson has been very clear in specifying the psychophysical relations between mind and brain (Hobson actually thinks these are so tight that, in his writing, he consistently uses the term mind-brain, implying that for him these two entities are one and the same thing).  But Hobson's theory hasn't gone uncriticized.  For example, the model drives psychoanalysts completely bananas.  

One psychoanalyst, in particular, has been critical of Hobson -- but, interestingly, this criticism is not based so much on psychoanalytic considerations as on neuroscientific ones.  Specifically, Mark Solms, (2000), a  British psychologist, has offered neuropsychological evidence that certain kinds of forebrain damage impair dreaming.  The sites of this damage lie outside the midbrain reticular formation and pons, and for that matter lie outside the circuit that carries PGO waves.  

Solms_2000_Fig2.jpg (33912 bytes)Solms (1997) surveyed a representative sample of neurological patients about their dreaming, and obtained the following results:



Put another way, the patients who lost the capacity to dream did so even though the pontine structures that generate REM activity remained intact.  Put another way, dreaming can be dissociated from REM activity.  Which means that the same process that generates cyclic REM activity does not generate dreams. 

Solms also argues the dreams and REM sleep are dissociable.  He notes that about 5-10% of NREM awakenings yield dream reports that are indistinguishable from those collected in REM, while 5-30% of REM awakenings yield no dream reports.  This suggests to him that whatever role PGO spikes play in REM, they are neither necessary nor sufficient for dreams to occur.

Solms_2000_Fig1.jpg (49122 bytes)According to Hobson, the module that generates REM is presumably located somewhere in the pons (which is why it's referred to as the PGO system), particularly brain-stem nuclei such as the locus coeruleus and the tegmentum.



Solms_2000_Fig3.jpg (49560 bytes)But, according to Solms,  dreaming -- as opposed to REMs -- is controlled by a dopamine-based network of forebrain structures, including the amygdala and the hypothalamus.  These forebrain mechanisms are critical for dreaming. Cholinergic systems located in the pons control REM, but frontal/dopaminergic systems control dreaming.  Therefore, pontine damage will suppress REM, but not dreams, while frontal damage suppreses dreams, but not REM.  Solms refers to this as a double dissociation.

So Solms offers yet another neuroscientific dream theory, based on a dopaminergic hypnothesis of dreaming (recall from your introductory psychology course that there is also a "dopaminergic hypothesis" of schizophrenia: this isn't a coincidence, as dreams are by their very nature hallucinatory).  According to Solms, damage to the forebrain interrupts the mesocortical/mesolimbic dopamine system, which eliminates dreaming while having no effect on REM sleep.  In support of his theory, he notes that L-dopa, which is a precursor to dopamine and the other catecholamine neurotransmitters, stimulates vivid dreams and nightmares, while haloperidol, a dopamine antagonist and popular antipsychotic medication (no coincidence, there) inhibits frequent and vivid dreams.  The dream-generation process is not associated with pontine activation or PGO waves or anything like that.  Instead, it's a product of cerebral activation during sleep.  In any event, Solms claims that dreaming may have many different origins, not just in pontine activity.

As part of his theory, Solms (2000) postulates a "dream-on mechanism", whose roots are in the mesocortical/mesolimbic dopamine system -- the ventral tegmental area (VTA), amygdala, and prefrontal cortex.  Recalling that the dopamine system is also the so-called "reward system" in the brain, he offers an alternative take on Freud's theory of dreams as wish-fulfillments.  Dreams are mental enactments of goal-directed behavior, generated by a "seeking system" that operates on a principle of reward and pleasure.  Thus, Solms's theory is an expercise in neuro-psychoanalysis.

Now, this doesn't sound very psychoanalytic, but you've got to remember that modern psychoanalysts aren't as obsessed with primitive, infantile sexual and aggressive impulses as Freud himself was.  Solms appears to think this lines up with a generic psychoanalytic view, because it implicates structures like the hypothalamus, which is involved in motivation, and the amygdala, which is involved in emotion; and not so much the cerebral cortex itself, which would be the seat of "rationality".  Put another way, dreaming has its sources in a "seeking system" that governs appetitive motives -- that is, the desire to approach things; and that's Solms' interpretation of the Freudian libido. 

But the fact is that Solms is more interested in critiquing Hobson's neuroscience than he is in defending a psychoanalytic theory of dreams and their meaning.  In the first place, he disagrees with Hobson's identification of dreaming with REM sleep; Solms agrees with Foulkes that genuine "dreamy" dreams can occur in NREM as well.  All their other differences flow from this basic difference.

As noted by Domhoff (2005), these differences include:

At the same time, Domhoff (2005) has also identified some similarities between them:

Which brings us to Domhoff's own position, which he presents as a kind of middle-ground view.


Domhoff's Critique

This focus on dream content lies at the center of Domhoff's alternative theory of dreaming, discussed below.  For now, the heart of Domhoff's critique of Hobson is not directed at his neuroscience, which is Solms' tack, but rather at his psychology.  In particular, Domhoff (2005) insists that dreams are nowhere near as bizarre, illogical, chaotic, and emotional as Hobson assumes them to be.  

Domhoff points out that one of the seminal studies of dream content, by Snyder et al. (1970), concluded that dreaming is "a remarkably faithful replica of waking life".  Most dreams have commonplace, rather than exotic, settings.  The most frequent activity reported in dreams is talking; active exertion is relatively rare.  The majority of dreams are highly coherent, and not particularly bizarre.  

These findings were essentially confirmed by other large-scale studies of dream content, such as that of Hall and van De Castle (1966), and Domhoff's own studies (Domhoff was a student of Hall's; and Hall, perhaps somewhat paradoxically, is the author of A Primer of Freudian Psychology, the best short summary of classical Freudian theory available anywhere).  

Put another way, dragons hardly ever ride bicycles down the Champs Elysees.  If Hobson's AIM model seeks to explain, in neurochemical terms, why dreams are so bizarre, then it is seeking to explain something that isn't true. 

There is an important methodological issue here, which concerns the degree to which dreams elicited in the laboratory, or recorded at home are representative of dreams as a whole.  This issue is not as easy to resolve as it sounds.

The fact his, however, as Domhoff (2005) has pointed out, that neither lab nor home dreams contain the large amounts of bizarreness and emotionality that Hobson (and Solms too, for that matter) ascribes to them, and the frequency with which bizarreness or emotionality appear in dreams does not differ significantly between lab and home collection-sites.  Nor, for that matter, is there much evidence that dreams differ all that much on these dimensions from samples of thoughts collected from subjects who are sitting, wide awake, in a darkened lab room. 

But Domhoff's critique is not confined to the psychological side of the equation.  He also criticizes Hobson's (and Solms') neuroscience. 

Still, the focus of Domhoff's critique is that Hobson has begun with an incorrect description of dreams at the psychological level of analysis.  And, as I'm fond of saying (e.g., Kihlstrom, 2010):

if the psychology is wrong, the neuroscience can't be right.


The Meaning of Dreams

If Hobson is right, dreams are essentially meaningless, the product of neural representations that just happen to be activated during REM. If they are not entirely meaningless, then they are essentially continuous with pre-sleep waking thought, and thus have no special significance -- in other words, that they are essentially epiphenomenal, mere byproducts of a physiological state of heightened cortical activation.


Modern Psychodynamic Approaches

But Hobson's theory has not gone unchallenged.  

              (94363 bytes)For example, for all of the 20th century, and even now in the 21st, there is still widespread embrace of Freud's theory that dream images are "Monsters from the Id" (a line from Forbidden Planet, my favorite science-fiction movie of all time), symbolic representations of unconscious thoughts, feelings, and desires, and that dreams were "the royal road to the unconscious".


A similar view has been proposed by theorists outside the psychoanalytic community.  For example, Louis Breger argued that dreams reflect the assimilation of waking experience into existing mental structures, as the person consolidates memories for the events of the previous day.  Moreover, Breger argued that dreams allow the dreamer to test out, symbolically, possible solutions to problems encountered in waking life -- or, at least, to anticipate these problems.

An excellent example of the dream as creative problem-solving is provided by Kekule's story of his discovery of the chemical structure of benzene.  Actually, Kekule told two such stories (see A.J. Rocke,  Image and reality: Kekule, Kopp, and the Scientific Imagination (2010).

Every teacher I have ever known, from kindergarten through university, regularly suffers from "school-mares" before the beginning of the academic year.  (Research alert: turn this anecdote into an actual empirical study.)

Students, too, often suffer from "test-mares" before important examinations -- for example (following a scenario originally concocted by Daryl Bem), sitting alone in the dark, taking a test with a snake on the desk.  (There's a lovely senior thesis to be done on this question, too!)


A Cognitive Theory of Dreaming

Still, many modern theorists follow Hobson in considering dreams to be essentially epiphenomenal.  That is, dreams are purely a byproduct of brain activation.  They are "real" enough, while they're happening, but they serve no psychological function.

Of course, this position is absolutely false in at least one respect: we are disturbed by our nightmares, and we are often so struck by our dreams that we tell other people about them.  So, in that limited sense, dreams do have an effect on our behavior.

More important, though, David Foulkes (1985) offered a cognitive theory of dreaming.  More or less in line with the early Hobson-McCarley activation-synthesis theory, Foulkes proposes that dreams begin  with the essentially random activation of stored memory traces.  These elements are then integrated into a more or less coherent dream experience.  But he differs from the implication of the activation-synthesis theory that dreams are, essentially, epiphenomenal.

So far, Foulkes' theory looks like it's not all that incompatible with the activation-synthesis view (remember, Hobson hadn't yet proposed his AIM makeover of activation-synthesis theory).  One difference, however, is that Foulkes argues that there's just one dream-production system, operating at all stages of sleep -- which is why he's so interested in evidence that dreams -- real, dreamy dreams --  occur in NREM as well as REM sleep.  So, a great deal rests on this question: do dreams occur in NREM, and if so where do they come from?  Are they actually generated in NREM, or are they just memories from REM dreams, carried over into the subsequent NREM period?

The Development of Dreaming

One of Foulkes' major contributions has been his study of children's dreams (1982).  Because, in his view, dreams draw on the dreamer's knowledge and experience, the dreams of children should differ significantly from those of adults.  To which Foulkes adds considerations of Piagetian developmental stages, suggesting that the dreams of pre-operational children should differ from those of children who have reached the stage of formal operations.  And, setting aside Piaget's theory, dreams should develop in parallel with the developing linguistic competency of the child.

The implication of all of this, for Foulkes, is that dreaming is a product of the dreamer's knowledge and experience -- more closely tied to thought than to visual or other imagery.  Viewed in terms of Piagetian stage, pre-operational children just don't have the cognitive abilities to support dreaming.  Once they achieve cognitive operations, their dreams are not very different from those of adults.


A "Neurocognitive" Theory of Dreams

Domhoff (1996, 2003, 2001, 2005, 2010) has proposed a "neurocognitive" theory of dreams that expands on Foulkes' ideas.  For Domhoff, the content of dreams is shaped by both current personal concerns (the "continuity principle") and past emotional preoccupations (the "repetition principle").

Domhoff has been critical of Hobson's initial activation-synthesis theory and the later AIM model of dreaming.  Principally, he points to the essential similarity between dream reports extracted during REM and those extracted during NREM, especially from Stage 2.  These essential similarities, he claims, refutes AIM's emphasis on REM activation as the basis for dreaming.  For Domhoff, there is an "uncertain" relationship between dreams and physiology. 

Domhoff begins with Snyder's (1970) extensive study of dreams collected in the laboratory following dream awakenings, which found that "dreaming consciousness" is a "remarkably faithful replica of waking life" (p. 133).  Snyder reported that REM dreams were typically coherent, detailed accounts of realistic situations in which the dreamer and others were engaged in fairly ordinary social activities, including conversation: the typical dream is a "clear, coherent, and detailed account of a realistic situation involving the dreamer and other people caught up in very ordinary activities and preoccupations, and usually talking about them" (p. 148).  Snyder found that up to 90% of dream reports "would have been considered credible descriptions of everyday experience (Snyder et al., 1968, p. 375).  Yes, some dreams are bizarre. But, Domhoff points out, so are some of the thoughts and daydreams we have in the ordinary course of everyday living.

Domhoff then points to studies like Foulkes's, which show clear developmental trends in dreaming -- trends which are highly correlated with the child's level of cognitive and linguistic development.  From this, Domhoff concludes that dreaming is a "cognitive achievement" that depend on the same processes that govern the person's normal waking cognition.  

To further characterize the dream process, Domhoff then turns to a large corpus of dreams, collected first by Hall and Van de Castle (1966) -- Hall, a UC Berkeley graduate, was Domhoff's advisor in graduate school -- and later by his own research group.  These dreams have all been analyzed in terms of a coding scheme originally developed by Hall and Van de Castle.  One of the things that emerges from longitudinal studies of dreams is that, while the specific content of dreams varies from night to night, the themes and contents of an individual's dreams are remarkably stable over fairly long periods of time.  Most important, Domhoff and his colleagues have found that the themes of individuals' dreams are significantly associated with the concerns, interests, and situations that characterize their waking lives.  In any case, most dreams are faithfull to everyday life, in that they represent commonplace, familiar settings, have a low degree of drama and other emotion; thinking in dreams is generally coherent, and ther is a relatively low level of bizarreness.
Here's the "cognitive" part of Domhoff's neurocognitive theory: dreams, being essentially continuous with normal waking thought, are best thought of as constructed by the same cognitive processes that generate thoughts, images, and stories in the normal waking state.  Dreaming is a "complex cognitive achievement" that depends on a relatively mature set of cognitive skills.  Although it is clear to Domhoff that dreams have psychological meaning, the same sort of meaning that waking thought has, it is not clear to him that dreaming itself is adaptive.  However, dreaming is the product of cognitive faculties that are, themselves, highly adaptive, specifically:

Young children tend to lack these cognitive abilities, which is why they seldom dream.  Various cultures may make use of dreams in various ways, but that does not mean that dreaming per se has any adaptive significance, for the individual or the species.

And so here's the "neuro" part: Both waking and dreaming cognition are products of a neural network that includes the limbic, paralimbic, and association cortices, which form a closed loop and, during sleep, operate largely independently of prefrontal cortex, sensor-motor cortex, or primary visual cortex.  Thus, dreams are generated internally, not by external stimulation; and they are experienced as involuntary, rather than voluntary.  

Link to an early precis of Domhoff's theory, which is one page on his excellent website, devoted entirely to dreams.  An updated statement of his theory, complete with commentary on Hobson and Solms, is also available there.  If you want to do your own analysis of dream content -- to determine, say, the frequency with which dragons ride bicycles in the dreams of Argentinian college students -- you can work with the entire corpus of dreams at Domhoff's "DreamBank" website.

A related project, announced in 2020, is the "DreamCatcher" project run by Luca Aiello and the social dynamics group of Nokia Bell Labs at Cambridge University.  They are using an artificial intelligence system known as Natural Language Processing to scan thousands of dream reports -- including Domhoff's DreamBank database -- in order to identify recurring patterns.  The system also scores the dreams on various dimensions using the scales originally developed by Hall and Van de Castle, as described earlier.  So far, the results are compatible with Domhoff's theory: we dream at night what we think about during the day, and the situations we encounter in our dream life are the same as those we've encountered while awake.  But now the theory has the imprimatur of super-duper Big Data analyses, which may make it more palatable to some people.

The term "DreamCatcher" is, of course inspired by Native American spiritual practices, and the logo of the project is a representation of a dreamcatcher.  But it's more than a logo: a researcher can portray a summary of an individual's dreamlife on the dreamcatcher framework, with the feathers representing various themes and the web inside the hoop representing the links among the themes. 

Another project, led by Dierdre Barrett, a psychologist at Harvard Medical School, collected dreams during the summer of 2020 that were related to the Covid-19 pandemic.  She and other researchers reported a dream surge -- more people (surveyed online at the peak of the pandemic) reported dreams (meaning, more people remembered dreaming upon awkening in the morning), and more dreams had content plausibly related to the pandemic (including dreams about computer viruses).  See "Infectious Dreams" by Tore Nielsen, a prominent dream researcher, Scientific American, 10/2020). 

Yet another, led by Kelly Bulkeley, a psychologist of religion who has taught at the Graduate Theological Union in Berkeley, is the Sleep and Dreams Database.  Like Domhoff's, it contains thousands of dream reports collected from individual, plus a suite of analytical tools. 

DomhoffQuantStudDreams.JPG (134090 bytes) DomhoffDreamBank.JPG (114774 bytes)


NEXTUP: Another Neuroscientific Approach to the Meaning of Dreams

Another recent approach to the meaning of dreams is an offshoot of Hobson's AIM model.  According to AIM, dreams are essentially meaningless, produced by the random activation of neural networks during REM sleep.  Reflecting recent evidence that REM sleep plays a role in memory consolidation (e.g., the work of UCB's Matt Walker, and a fascinating study indicating that rats replay during REM the route through a maze they had learned the previous day), Antonio Zadra and Robert Stickgold (the latter a longtime associate of both Hobson and Walker), have proposed that (When Brains Dream: Exploring the Science and Mystery of Sleep, 2021) dreams allow us to explore long-term memories, fitting them into a narrative structure that allow us to explore various possibilities that might not be possible, or might even be dangerous if pursued in waking life.  They call their theory NEXTUP, which stands for "Network Exploration to Understand Possibilities". 

This page last modified 10/22/2021.