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 dreaming. Or is there?
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.
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
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.
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:
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
Still, it must be remembered
that even Freud, somewhere, said that "Sometimes a cigar is
just a cigar".
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.
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
The first of these mental lenses, called the System Cs (for conscious), contains those percepts, ideas, memories, impulses, and actions of which the person is presently aware.
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
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.
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.
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.
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:
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
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.
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).
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.
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.
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
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:
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.
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.
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.
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.
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.
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.
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.
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.
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.
But 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.
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,
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.”
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.
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
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
|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.|
|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.|
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:
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 (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.
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.
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.
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
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.
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.
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 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.
But Hobson's theory has not gone unchallenged.
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
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!)
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.
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
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.
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
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"
This page last modified 08/22/2017.