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Absorption, Daydreaming, and Absent-Mindedness

Some altered states of consciousness take place in the ordinary course of everyday living, while other, more profound, "mystical" experiences require disciplined training in meditation.  In either case, the alteration in consciousness appears to be mediated by an alteration in attention.

Traditionally, it has been assumed that there is a close relationship between consciousness and attention. We become consciously aware of objects and events by virtue of paying attention to them. 'Preattentive" processing is preconscious processing. However, Koch and Tsuchiya (2007) noted that the relationship between attention and consciousness is more complicated that that, and that it is possible to construct a 2x2 table consisting of the crossing of two factors: Attending-Not Attending and Conscious-Not Conscious.

Still, there are a number of attentional lapses in consciousness, discussed in the lectures on Attention and Automaticity and Implicit Cognition (Mack & Rock, 1998; Kim & Blake, 2005; Kanai et al. , 2010).

These attentional failures of consciousness occur under strictly controlled laboratory procedures. In these lectures, however, we are going to focus on alterations in consciousness, mediated by alterations in attention, that occur outside the laboratory in the ordinary course of everyday living.


Absorption was defined by Tellegen (1987) as a cognitive restructuring of the self and of ego boundaries, involving narrowed or focused attention, and a departure from everyday modes of thought.  An informal content analysis by Tellegen and Atkinson (1974) indicated that absorption has a number of different elements, including:


Dimensions and Correlates of Absorption

014AbsorbAspects.jpg (114484 bytes)While the peak experience and flow are generally assessed impressionistically, Tellegen has developed a specific instrument, the Tellegen Absorption Scale, to measure individual differences in absorption.  Factor-analytic studies of the internal structure of the TAS reveal six major dimensions of absorption.



Absorption, in turn, is related to the Openness to Experience dimension (Factor V) of the Big Five" structure of personality:

On the NEO Personality Inventory (named after Neuroticism, Extraversion, and Openness),Openness to Experience is measured in terms of six "facets":

Openness is the latest iteration of a dimension that, in the late 1940s, was called intellectance, and in the mid-1960s was called culturedness.

Actually, research from my laboratory indicates that Openness to Experience is actually composed of three dimensions which are conceptually and empirically quite different from each other.

017AbsOpeHyp.jpg (64107
        bytes)The best-documented correlate of absorption is hypnotizability -- although the correlations are not nearly high enough to permit the Absorption Scale to predict response to hypnosis.  Not surprisingly, hypnotizability is also correlated with Openness to Experience, although the correlations are much higher for those facets that are conceptually related to absorption, than for those facets that are related to "liberalism".



              (85924 bytes)Openness is also related to a dimension of personality sometimes known as intellectance.  Hypnotizability is related to the absorption component of openness, but not to either socio-political liberalism or intellectance.  



Absorption, intellectance, and liberalism are probably not closely tied together -- they appear to fall together in analyses of the "Big Five" personality traits for psychometric reasons that are, frankly, boring. The important point is that people can get absorbed in experiences and activities even if they don't have particular intellectual leanings, and even if they're not particularly liberal in their political and social attitudes! 

We have probably exhausted the research we can do on absorption with impressionistic or questionnaire measures of the construct. Now it is time to start experimental research on the cognitive mechanisms of absorption and flow (hint, hint...).  

Imaginative Involvements

A clinical interview study by Josephine Hilgard (1970) found that people who are highly hypnotizable had a history of strong "imaginative involvements" in various domains.  

The Book-Reading Fantasy

Ronald Shor (1970) expanded the notion of imaginative involvement in reading into the book-reading fantasyIn this phenomenon, readers become so engrossed in what they are reading that they are oblivious to other things going on around them:

  • Vivid imagination: The experience of reading is equivalent to living the experience itself, creating a fantasy that is totally compelling. Visual imagery stimulated by the text may be in color, and it may be three-dimensional; but all modalities of imagery may be involved.
  • Oblivious to true reality: during the time that they are engrossed in a text, absorbed readers may "tune out:" external stimuli that might distract them from the reading experience.
  • Unaware of active imagination: the absorbed reader is swept away by the book, but is unaware of the fact that he or she is actively creating the fantasy experience in his or her own imagination.
  • The reader may be alert to important events, but this "alertness" occurs at a nonconscious level, rather than as an active, deliberate, conscious scanning of the environment.

Hilgard (1970), for her part, identified two different types of book-reading fantasy:

Hilgard also identified a number of characteristics of involved readers, who are especially susceptible to the book-reading fantasy.

Victor Nell (1988), a South African psychologist, developed the concept of ludic reading, or reading for pleasure, which he argued entailed an actual change in consciousness through "the world-creating power of books" and the reader's effortless absorption" in the material being read.  

Ludic readers typically read at least one book per week of fiction or narrative nonfiction. 

The Method in Acting

The Russian theater director Constantin Stanislavski (1863-1938) developed the concept of The Method (Stanislavski himself called it "The System") in acting, by which the actor becomes completely absorbed in his or her role.  The Method, which is clearly distinguished from technical acting, was rechristened and popularized in the United States through the Group Theatre and the Actor's Studio in New York, led by Lee Strasberg, Stella Adler, and Harold Clurman, and whose products included Marlon Brando, James Dean, Marilyn Monroe, and Paul Newman (among among others in the generation of stage and film stars that came to prominence in the 1950s and 1960s), as well as (among a later generation, in the 1980s) Robert DiNiro, Dustin Hoffman, and Al Pacino.  The System, as conceived by Stanislavski, required actors to set aside their own self-consciousness and embrace the inner lives, the inner desires, of the characters they're playing.  Strasberg's Method focused on the actor's personal emotional memories (Stanislavski himself rejected Strasberg's interpretation of his Method).  While Strasberg's Method required actors to delve deeply into their inner selves, Adler's variant asked the actor to "enlarge your own soul to meet -- or become worthy of -- the character you were to play".

For a history (actually, the author calls it a "biography") of Method acting, see The Method: How the Twentieth Century Learned to Act by Isaac Butler, reviewed by Simon Callow -- who in his review is quite critical of both Strasberg and The Method -- in "Shape-Shifters", New York Review of Books, 08/18/2022.  Butler summarizes The Method by pointing out the Pacino "became known in the industry for his ability to 'absorb' people, watching them intensely and then somehow, mysteriously, taking on their essence and embodying it".  Callow, himself a distinguished British actor and director, adds that Pacino "was an example of what actors have alarmingly been from the dawn of time: shape-shifters stealing people's souls.  That... is somehow the domain of the Method".

Flow and the Peak Experience

Csikszentmihalyi (pronounced CHICK-sen-mee-hai, just like it's spelled) and his colleagues (1988, 1990) have developed the concept of flow, "a state in which people are so involved in an activity that nothing else seems to matter.  The connection to absorption and the book-reading fantasy is clear.Csikszentmihalyi defines flow as an "optimal experience" with several characteristics:

Flow, in turn, is an aspect of what Maslow's (1954, 1968) has called the peak experience.  In the 1950s, Abraham Maslow developed a theory of motivation centered on a pyramid of needs. In Maslow's view, needs at a particular level of the pyramid can be satisfied only once needs at all lower levels have been satisfied.  

Achievement of self-actualization gives rise to the peak experience, which Maslow describes in almost mystical terms: "the experience or the object tends to be seen as a whole, as a complete unit, detached from relations, from possible usefulness, from expedience and from purpose".  In such a state, Maslow thought, the subject experiences a "unity of consciousness" in which "the whole world is seen as... a single rich live entity".

011MaslowMethod.jpg (117082 bytes)Maslow trained as an experimentalist (at Wisconsin, under Harry Harlow, doing research on rhesus monkeys no less), but when it came to studying the peak experience, all he could do was fall back on subjects' self-reports of "the most wonderful experience" in their lives, which were then coded impressionistically to yield the characteristics of the peak experience described above.

More recently, UCB's Dacher Keltner and his colleagues have developed a method for studying the related experience of awe (Keltner & Haidt, 2004).  In one study, for example, Shiota et al. (2007) exposed subjects to the Tyrannosaurus Rex skeleton on the UCB campus.  This procedure was successful in eliciting feelings of awe in many subjects. 

Link to Faculty Lecture by Dacher Keltner on "The Evolution of the Sublime: The Science of Awe" (09/05/2014).  Apparently there are different kinds of awe.  Usually, researchers focus on a positive form of awe, but there is also a negative (threat-based) awe.  And while awe is often elicited in natural settings, there is also a non-nature form of awe. 

As Keltner and his colleagues note, nature is particularly likely to inspire awe.  Here are two extracts from the writings of early visitors to the Yosemite Valley, taken from The National Parks: America's Greatest Idea (2009) by David Duncan and Ken Burns, based on Burns's PBS film of the same name.  (Image: "Yosemite Valley", 1868, by Albert Bierstadt, on view at the Oakland Museum of California.)

Early in 1851, during the frenzy of the California Gold Rush... the Mariposa Battalion... came to a narrow valley surrounded by towering granite cliffs, where a series of waterfalls dropped thousands of feet to reach the Merced River on the valleuy's floor.  One of the men, a young doctor named Lafayette Bunnell, found himself transfixed by the vista.  "As I looked, a peculiar exalted sensation seemed to fill my whole being," he wrote, "and I found my eyes in tears with emotion.  I said with some enthusiasm... "I have here seen the power and glory of a Supreme Being: the majesty of His handy-work is in that 'Testimony of the Rocks'".

James Mason Hutchings, leader of a group of tourists(!) in 1855, wrote of their experience of viewing Yosemite Falls:

Descending towards the Yo-Semite Valley, we came upon a high point clear of trees, from whence we had our first view of the singular and romantic valley; and as the scene opened in full view before us, we were almost speechless with wondering admiration at its wild and sublime grandeur....  If man ever feels his utter insignificance at any time, it is when looking upon such a scene of appalling grandeur.

Now, that's awe!

Perhaps even more dramatic, but less accessible to mere mortals, is what is known as the overview effect, an "intense state of self-transcendent awe and wonder" experienced by astronauts when they view the Earth (the "Big, Blue Marble") from space -- an "explosion of awareness", as described by astronaut Edgar Mitchell.  The term was coined by White (1987), who collected anecdotal reports of the effect (the famous image on the left, entitled "Earthrise", was taken by astronaut William Anders in 1968).  See also the article by Yaden et al. (Psychology of Consciousness, 2016)


Dacher Keltner, Evolution of the Sublime: Toward a Science of Awe - See more at: http://psychology.berkeley.edu/watch-our-videos#sthash.fDO2kFot.dpuf
Dacher Keltner, Evolution of the Sublime: Toward a Science of Awe - See more at: http://psychology.berkeley.edu/watch-our-videos#sthash.fDO2kFot.dpuf

Flow and Positive Psychology

Just as Maslow's concept of self-actualization was at the center of the humanistic psychology that developed in the 1950s and 1960s as an alternative to both psychoanalysis and behaviorism, so Csikszentmihalyi's concept of flow is an important component of the positive psychology that began to emerge in the 1990s.

Although they're obviously related, there are some important differences between humanistic and positive psychology. For a comparative analysis, see Waterman (2013).


Absorption, Flow, and Everyday Life

People can become absorbed in, and experience flow during, even the most mundane activities.  Consider this precis of the Mind at Work by Mike Rose (2004), as reviewed by Matthew B. Crawford in the Wall Street Journal, 09-05-06/2009:

You might consider getting a job waiting tables after reading Mike Rose's "The Mind at Work".  Rose emphatically does not romanticize the workers he describes, who include electricians, welders and waitresses.  Rather, he shows how mentally absorbing work can be for those who cultivate a particular skill, however narrow that skill might seem. A restaurant is both structured and chaotic.  The busier it gets, the more "on" an experienced waitress tends to become, at once calmed and energized by an awareness of her own skillful performance.  She moves in a circuit of heightened efficiency that gets smoother with each added demand.  She does this while keeping the cook happy and the cranky customer docile, and playing you like a fiddle to get a bigger tip.  She is a sort of entrepreneur.  In this deeply humane book, Rose helps us see the human excellence on display all around us, in jobs that often go unnoticed.


Daydreaming and Mind-Wandering

If in absorption attention is tightly focused on some experience, in daydreaming attention drifts away from its original object. 

Singer & Antrobus developed the Imaginal Processes Inventory to provide an exhaustive survey of the daydreaming experience.  They sat down and wrote items covering every conceivable aspect of daydreaming, resulting in a very long questionnaire.




020SIPIScales.jpg (89828 bytes)Because the IPI is somewhat unwieldy in actual use, Huba et al. developed a short form, the Short Imaginal Processes Inventory, which measures three broad dimensions of the experience.



Of course, people can become absorbed in their daydreams.  Although absorption and daydreaming would appear to be polar opposites, it's also true that people can become absorbed in their daydreams.  For that reason, there is actually a moderately high correlation between the two states.


021DDAbsHyp.jpg (68003 bytes)Hypnotizability is not as highly correlated with daydreaming as it is with absorption.  To the extent that hypnotizability is correlated with daydreaming at all, the correlations are strongest with positive-constructive daydreaming.



                  (48516 bytes)Experimental studies of daydreaming may serve as a kind of model for the sort of laboratory research that might be done on absorption.  In one early study, Antrobus (1968) recruited subjects for a vigilance task that lasted all of 2 hours!  the subjects were supposed to listen to a tape, and press a specific button whenever they heard a specific tone.  To keep subjects motivated over the course of this very long experiment, they were given a monetary reward for each hit.  Antrobus also varied the informational load, varying both the number of different tones (1, 2, or 3) and the rate at which they were presented (1 tone every 5, 1, 04 0.5 seconds).  Every 15 seconds, he used a "thought-sampling" method to probe for stimulus-independent mentation or task-unrelated intrusive thoughts (TUITs) -- that is to catch the subjects daydreaming.  The finding of the experiment was that daydreaming occurred frequently, but the more so under conditions of light cognitive load.  When the subjects' cognitive capacity was more fully engaged, the frequency of daydreaming went down.  But it was still pretty high, no matter what the informational load.

Based on more recent research of this type, Stawarczyk et al. (2010) has introduced a two-way classification of stimulus-independent and task-unrelated thoughts (SITUTs).  When thoughts are task-related and stimulus-dependent, the subject is performing the task as it is supposed to be performed.  Daydreaming occurs when thoughts are both task-unrelated and stimulus-independent.


Take the Imaginal Processes Inventory

Link to a page containing the SIPI and scoring instructions.



The Cognitive Failures Questionnaire (CFQ) was developed by Broadbent et al. (1982) -- yes, the same Broadbent who proposed the filter theory of attention -- to assess the frequency with which people experienced cognitive failures, such as absent-mindedness, in everyday life -- slips and errors of perception, memory, and motor functioning.  Scores on the scale predict episodes of absent-mindedness in both the laboratory and everyday life, including slow performance on focused attention tasks, traffic and work accidents, and forgetting to save one's data on the computer. 

A study by Rast et al. (2008) indicates that the CFQ items load on three different factors, or dimensions of absent-mindedness:

Take the Cognitive Failures Questionnaire

Link to a page containing the CFQ and scoring instructions.


If absorption and daydreaming count as altered states of consciousness, and absent-mindedness and mind-wandering count as lapses of consciousness, boredom also has to count as some kind of altered state of consciousness.

In a pioneering study of boredom by Thomas Goetz and his colleagues at the University of Konstanz (Motivation and Emotion, 2013), German high-school and college students were given PDAs (like Palm Pilots, for those who are old enough to remember them), which were programmed to signal the students at random six times per day.  Each time, the students were asked to report what they were doing and how they felt about it. Over the two weeks of the study, the subjects reported that the were bored almost 40% of the time!  Unfortunately, many of these reports were given during the subjects' academic classes.

Analysis of the resulting data, including the subjects' reactions to boredom and the situations in which they became bored, indicated that boredom came in at least four different forms:

  • Indifferent Boredom, or "a general indifference to, and withdrawal from, the external world".
  • Indifferent Boredom, or "a general openness to behaviors aimed at changing the situation".
  • Searching Boredom, "actively seeking out specific ways of minimizing feelings of boredom".
  • Reactant Boredom, involving a desire "to leave the boredom-inducing situation and avoid those responsible for this situation".

This much was expected from prior research and theory.  But the data also provided evidence for a fifth kind of boredom:

  • Apathetic Boredom, similar to Reactant Boredom, but lacking the desire to do anything about it.

A series of experiments by Timothy Wilson and his colleagues ("Just Think: The Challenges of the Disengaged Mind", Science, 07/04/2014) showed just how aversive boredom can be.  They asked their subjects to spend a short period of time, just 6-15 minutes, thinking about absolutely nothing.  They found this so difficult to do that they preferred to do almost anything else -- including administering electrical shocks to themselves!  The point is, as James noted in his great introspective analysis of consciousness, "thinking of some sort is always going on".  It takes great effort to suppress it -- and even with great effort we can't do it (except, perhaps, during periods of meditation, as discussed later).  Even when the mind is supposed to be focused, it tends to wander; and it wanders even more when it's not focused.


In a series of studies that combine daydreaming with absent-mindedness, Jonathan Schooler and his colleagues (2002) have developed a method for studying lapses of attention that occur during reading -- what is commonly called "zoning out".  Much like the Antrobus studies, the subjects are asked tor read an attention-demanding text, and then report instances of mind-wandering -- either self-caught, or in response to a probe from the experimenter.  One of the most interesting findings of these experiments is that subjects are often unaware of their mind-wandering.  Obviously, they're aware of mind-wandering when they catch it and report it themselves.  But apparently, subjects do not always realize that their minds have wandered from the assigned text until the probe draws their attention to it.

Based on findings such as these, Smallwood and Schooler (2006) have pointed to a paradox: mind-wandering is not just a matter of "zoning out.  Rather, attention has become decoupled from the subject's primary task, and shifted to the subject's own personal goals.  As in the Antrobus experiments, mind-wandering decreases during controlled processing, which consumes attentional resources.  But it increases with practice, as the subject becomes skilled at the task -- making more resources available.  This is the paradox: mind-wandering is more likely to occur, the more the subject is skilled at what he is doing.  Still, Smallwood and Schooler argue that mind-wandering occurs unconsciously: subjects have no conscious intention to shift attention away from the task at hand, and they are often not aware that such a shift has occurred.

Based largely on his studies of mind-wandering, Schooler (2005) distinguished among three levels of consciousness:



  • Basic Consciousness, consisting of the subject's current perceptions, memories, feelings, etc.
  • Meta-Consciousness, consisting of the subject's conscious reflection on the contents of basic consciousness.
  • Tacit Monitoring, which checks the contents of consciousness for failures to achieve goals, unwanted thoughts, and the like.

The Monastic Rules to Prevent Mindwandering

In what has been called the "attention economy" (Davenport & Beck, The Attention Economy: Understanding the New Currency of Business, 2001), individuals, businesses, and other organizations are constantly vying for our attention; and their ability to capture our attention means increased revenue, fame, and notoriety for them.  As a result, the world is full of distractions.  The situation has become increasingly dire with the advent of the internet (it was once called the World Wide Web), and later the widespread availability of personal computers, first towers and then laptops (you no longer had to go to a library or stay at the office to access it), and finally the proliferation of cellphones, tablets, watches, and similar devices that keep us snared in that "web" 24/7.

How to cope with all that distraction?

Here are some hints: turn off all notifications (yes, I did).  Unsubscribe to Facebook and Twitter (never subscribed in the first place).  Turn your phone off at 8PM, and don't turn it on until 7AM the next day (yes I do -- mostly; and unless I'm expecting an important call in the middle of the night, my phone and I sleep in separate rooms). 

It turns out that a world full of distraction isn't an entirely new phenomenon.  It was what Medieval monks experienced as they tried to devote their lives to the contemplation of God.  Their story is told by Jamie Kreiner, a professor of medieval history, in The Wandering Mind: What Medieval Monks Tell Us About Distraction (2023).  Casey Cep, reviewing the book in the New Yorker ("Eat, Pray, Concentrate", 01/30/2023), writes:

Kreiner uses the word “monk” inclusively, referring to both men and women, regardless of the form of monasticism that they practiced. During the period covered by “The Wandering Mind”—the fourth through the ninth centuries—monastic orders were still taking shape, their leaders devising and revising rules about sleep, food, work, possessions, and prayer. All these habits of being were an attempt to get closer to God, not least by stripping away worldly distraction, but how best to do so was a matter of constant experiment and debate. Routines and schedules circulated like gossip, with everyone wondering if some other order had arrived at a superior solution to the problem of focus, or yearning to know exactly how the apostle Paul or the Virgin Mary had arranged their days.


Giving up everything isn’t possible, of course: every body has a brain, and the brain is the greatest distraction technology of all. Half of “The Wandering Mind” is about how monks tried to maintain focus in the face of the world, their communities, their bodies, and their books, but the other half is about what they thought about thinking. Kreiner is fascinating on the ways monks attempted to manipulate their memories and remake their minds, and on the urgency they brought to those tasks, knowing the dangers that lurked even if they eliminated all physical temptations. A monk singing in church could be revelling in the memory of a delicious meal, while another, praying in her cell, might mistake the wanderings of her own mind for divine revelation.


Whether monks built arks, angels, or palaces, vigilance was expected of them all, and metacognition was one of their most critical duties, necessary for determining whether any given thought served God or the Devil. For the truly devout, there was no such thing as overthinking it; discernment required constantly monitoring one’s mental activity and interrogating the source of any distraction. Some monasteries encouraged monks to use checklists for reviewing their thoughts throughout the day, and one of the desert fathers was said to keep two baskets for tracking his own. He put a stone in one basket whenever he had a virtuous thought and a stone in the other whenever he had a sinful thought; whether he ate dinner depended on which basket had more stones by the end of the day.

Such careful study of the mind yielded gorgeous writing about it, and Kreiner collects centuries’ worth of metaphors for concentration (fish swimming peaceably in the depths, helmsmen steering a ship through storms, potters perfecting their ware, hens sitting atop their eggs) and just as many metaphors for distraction (mice taking over your home, flies swarming your face, hair poking you in the eyes, horses breaking out of your barn). These earthy, analog metaphors, though, betray the centuries between us and the monks who wrote them. For all that “The Wandering Mind” helps to collapse the differences between their world and ours, it also illuminates one very profound distinction. We inherited the monkish obsession with attention, and even inherited their moral judgments about the capacity, or failure, to concentrate. But most of us did not inherit their clarity about what is worthy of our concentration.

Medieval monks shared a common cosmology that depended on their attention. Justinian the Great claimed that if monks lived holy lives they could bring God’s favor upon the whole of the Byzantine Empire, and the prayers of Simeon Stylites were said to be like support beams, holding up all of creation. “Distraction was not just a personal problem, they knew; it was part of the warp of the world,” Kreiner writes. “Attention would not have been morally necessary, would not have been the objective of their culture of conflict and control, were it not for the fact that it centered on the divine order.”

Perhaps that is why so many of us have half-done tasks on our to-do lists and half-read books on our bedside tables, scroll through Instagram while simultaneously semi-watching Netflix, and swipe between apps and tabs endlessly, from when we first open our eyes until we finally fall asleep. One uncomfortable explanation for why so many aspects of modern life corrode our attention is that they do not merit it. The problem for those of us who don’t live in monasteries but hope to make good use of our days is figuring out what might. That is the real contribution of “The Wandering Mind”: it moves beyond the question of why the mind wanders to the more difficult, more beautiful question of where it should rest.

Schooler, like Singer & Antrobus, Stawarczyk et al. (2012), and other early daydreaming researchers, defined daydreaming or mindwandering (we'll use these two terms interchangeably, depending on the preferences of the researchers we're discussing), defined the state largely in terms of content: daydreaming and mindwandering occur when subjects are not thinking about what they're supposed to be thinking about.  That is what it means to have task-unrelated or stimulus-independent thoughts.  However, Christoff et al. (2016) have proposed a different approach -- one based on process rather than content.  That is, daydreaming occurs when there is an absence of strong constraints on the person's thinking.  These constraints come in two forms:

I'll say more about Christoff's ideas in the next section, when we discuss...

The Default-Mode Network in the Brain

Research on daydreaming, mind-wandering, and "zoning out" reminds us that the brain is always active -- even when it's not engaged in a particular mental activity.  This may seem obvious, but it wasn't always so self-evident.  As Raichle (210a, 210b) points out, historically, psychology and neuroscience have entertained two quite different views of brain function.

Sherrington's view dominated neuroscience for a long time.  You can see the effect pf this assumption in what might be called the standard paradigm for cognitive neuroscience.  Consider, for example, the paradigm employed in countless studies of functional brain-imaging.  Subjects are asked to perform some sort of task (like viewing pictures of familiar faces), and the experimenter records the activity of the brain while the subject is so engaged.  The experimenter also records brain activity during a control condition -- either a baseline in which the subject isn't performing any particular task, or in which the subject is performing some contrasting task (like viewing pictures of unfamiliar faces).  Brain activity in the control condition is subtracted from that in the experimental condition, to yield a pattern of activity that is specific to the task assigned ot the subject.  Especially when the comparison is between the experimental task and the baseline, it seems to me that the underlying (if often tacit) assumption is during the baseline condition the subject isn't thinking about anything at all.  Or, put another way, the brain is only active when subjects are engaged in some task.

More recently, however, neuroscientists have come to appreciate Berger's view, that the brain is intrinsically active.  The assumption of pure insertion -- that brain activity is instigated by external stimuli -- is now understood to be incorrect.  Some regions of the brain are active even during control tasks when subjects are resting with their eyes closed, or simply maintaining fixation on a visual target.  These regions are de-activated when the subject engages in goal-directed activity.  

So, in fact, there are two modes of brain activity:

In fact, Raichle and his colleagues (2001, 2010) have argued that task-negative activity entails a specific pattern of activation, which he calls the default-mode network (DMN).  Depicted in the slide at the left, the DMN consists of medial portions of the temporal lobe and prefrontal cortex, the posterior cingulate cortex, and the medial, lateral, and inferior portions of the parietal cortex.  The slide at the right compares brain activity in the "default mode" with activity under other conditions.

Actually, Christoff et al. have identified two, maybe three, default-mode networks -- or perhaps three somewhat dissociable components of a single big DMN.

Here's the kind of evidence that Christoff et al. obtained in support of these distinctions.  They employed an experience-samlpling technique, asking subjects to report what they were thinking about while brain activity was recorded with fMRI.   Activity in DNCORE and DNSUB3 increased increased during periods of task-unrelated thought, and internally-oriented thought, while activity in DNMTL increased when deliberate constraints on thought were weak.  Interestingly, when activity in DNMTL increased, subjects were unaware that they were engaged in task-unrelated thought.  This is reminiscent of Schooler's claim that, sometimes, subjects are unaware that they are daydreaming. 

Based on their research, Christoff et al. (2016) mapped out the interactions between various networks involved in attention and mindwandering.  For example, the DNMTL and the sensorimotor areas serve as sources of variablity in thought content (based on memory or perception, respectively).  At the same time, the salience networks, the dorsal attention network (DAN), and DNCORE automatically constrain the output of DNMTL and the sensorimotor areas, increasing the stability of thought.  Similarly, the frontoparietal control network (FPCN) is a source of deliberate constraint on thought.  The interactions among these networks give rise to various kinds of thinking.

Be that as it may, Raichle's fundamental point is well taken -- the brain is active all the time, not just when it's been stimulated -- though it's a little sad that we needed brain-imaging to be convinced of that!.  And it's interesting that the "default mode" is not just some level of overall background brain activity, involving the cerebral cortex as a whole, but rather a specific network of brain regions.  However, I think it's a mistake to identify the DMN with daydreaming or mind-wandering -- simply because daydreaming and mind-wandering are mental activities as well.  When you're daydreaming, your thinking about the content of your daydream.  Even when you're engaged in mind-wandering, your mind is wandering from one idea or image to another.  There's always content.  Apparently, the DMN is the neural basis of that spontaneous thinking.

Apparently related to the DMN is an extremely slow, spontaneously occurring brain-wave  -- less than 0.1 Hz, compared to 1-4 H for the low-frequency delta activity discussed in the lectures on Sleep and Dreams, and named, appropriately enough, infra-slow activity (ISA), which is observed when organisms (including humans) are in the resting state.  A study by Raichle and his colleagues (Mitra et al., Neuron, 2018) found that the ISA, like delta activity, was observed when mice were resting (literally in a hammock!), but disappeared when they were anesthetized -- suggesting that ISA has something to do with consciousness.  In an interview ("Thinking Slow" by Tanya Lewis, Scientific American, 07/2018) Raichle offered an oceanographic analogy: ISA is like a groundswell, running underneath visible waves; task-specific activity, reflected in higher-frequency brain waves, then is like whitecaps, which are formed from the groundswell.  Maybe.  Or maybe ISA is just another brain wave.  

Discovery of the DMN signals a victory for Berger over Sherrington, but it also has implications for the identification of functional specializations in the brain.  Consider, again, the standard paradigm for cognitive neuroscience, discussed above.  In such studies, the researcher is interested in identifying the neural module, or system, that performs some function -- such as recognizing a face.  In fMRI, subjects are scanned while they're performing the task in question, and they're also scanned while performing some control task - -such as recognizing a word or describing a face.  The brain activity recorded while performing the control task is subtracted out of the brain activity recorded while performing the target task, leaving only the activity that is specific to performing the target task.  This subtractive method is, essentially, the same one used by Donders in his 19th-century reaction time studies aimed at decomposing mental processes, and by Sternberg for the same purpose at the dawn of the cognitive revolution in the 1960s. 

But it's obvious that the identification of some functional specialization depends entirely on what's been subtracted out.  If you're interested in the neural system that recognizes faces, you'll get different results if your control task involves recognizing words, than you would if your control task involves recognizing faces.  The implication is that, if you want to accurately delineate the DMN, you have to pay just as much attention to the control task as you do in standard functional neuroimaging experiments.

It seems to me that, in order to identify the true default mode network (TDMN), we'd need to find a network which is active when the subject is thinking of nothing at all, and deactivated when the subject is thinking of anything at all.  Ideally, the experiment to identify the TDMN would contrast three different states:

Only one minor detail: how to get subjects to think about nothing.  In fact, that's precisely the goal of certain Eastern meditative traditions, to which we now turn.

Link to Lecture Supplement on Meditation

This page last revised 07/07/2023.