The Wandering Mind

by Michael C Corballis

  Corresponding dream report: My dad and I leave to go shopping. We go from room to room, store to store. One of the stores is filled with muffins, muffins, muffins from floor to ceiling, all different kinds, I can’t decide which one I want . . .

  REM dreams can be quite prolonged, and probably occur in real time, unfolding as they would if they were happening in the actual world, whereas NREM dreams flit by in a fraction of a second, at least as judged from the ripples in the rat hippocampus. It is well established that NREM sleep is important for the consolidation of learning. In one study, people were trained to navigate a virtual maze, and did much better following an afternoon nap in which they dreamed about the maze than if they dreamed of something else. Their after-nap performance was unaffected by waking thoughts about the maze. Best get a good night’s sleep after studying for that exam.

  In this study, too, the dreams were not exact replays. Two participants reported hearing the music associated with the maze task, but did not dream of the maze itself; three others described other maze-like environments. Part of the consolidation process, then, seems to go beyond an exact experience so that people—and rats—gain a wider understanding of what they have learned, and perhaps greater adaptability to the future. I suggested in Chapter 4, though, that these dreams, and their daytime equivalents, are also the basis of mental time travel, with an eye to the future rather than the past.

  Our brains, then, are far from dormant during the night. With the absence of sensory stimulation and paralysis of movement, and under the cover of darkness, they seem to take the opportunity to service the mind as well as the body, just as your car needs to be serviced from time to time to check the wearable parts and tune its performance. Mental servicing includes emotional regulation during REM sleep, and the consolidation and expansion of our memories during NREM sleep. The two are also distinguished in terms of the chemistry of the brain. One such difference has to do with acetylcholine, which is a neurotransmitter—that is, it influences the efficiency with which neurons in the brain connect with one another. Acetylcholine is at a minimum during NREM sleep, and is also reduced in ‘quiet wakefulness’, when people, and perhaps rats, are apt to daydream. Lowering of acetylcholine is thought to promote consolidation of memories by supporting the flow of information from the hippocampus to other parts of the brain, where the details of memory are stored. In REM sleep, in contrast, the levels of acetylcholine are higher than they are when we’re awake, which is perhaps another reason why we find it virtually impossible to remember REM dreams.

  Much of the theory of dreams seems to focus on the negative—the threats, the traumas, the failed exam, the harping on past misfortunes and embarrassments. We should remember, though, that many of our dreams are positive, and fun to be part of. Dr Seuss, whose children’s stories are themselves a bit dream-like, was quoted as saying: ‘You know you’re in love when you can’t fall asleep because reality is finally better than your dreams.’ This morning, my four-year-old granddaughter tells me she dreamt of Pooh and Tigger. But she enjoyed telling it—the Tigger of A. A. Milne’s House at Pooh Corner doesn’t have the fearful symmetry of William Blake’s Tyger. And as bears go, Pooh is as lovable and cuddly as anyone’s teddy bear.

  Dreams may seem a wasted form of mind-wandering, since we forget nearly all of them. Rather than providing conscious nutrients for our waking lives, they may serve rather to activate the unconscious, to create the internal terrains for later mental meanderings. Occasionally, we do remember our dreams, and sometimes these form the basis for creative ideas, as I shall illustrate in the final chapter. First, though, I consider another form of mind-wandering that, although largely beyond our control, can remain in memory and affect our conscious lives.

  8.

  HALLUCINATIONS

  …

  A hallucination is a fact, not an error. What is erroneous is a judgement based upon it.

  —Bertrand Russell, from Theory of Knowledge

  The word ‘hallucination’ was first used in the early sixteenth century simply to mean ‘a wandering mind’, and what we now understand as hallucinations were called ‘apparitions’. In Shakespeare’s Macbeth, for example, the three witches summon up three apparitions, so named, to warn Macbeth that Macduff is coming back to Scotland to ruin him. The third apparition is a child holding a tree and wearing a crown, and declares:

  Macbeth shall never vanquish’d be until

  Great Birnam wood to high Dunsinane hill

  Shall come against him.

  Apparitions, like dreams, were thought to tell of the future, and later in the play Birnam wood was indeed seen as though moving to Dunsinane hill, contributing to Macbeth’s downfall.

  The term ‘hallucination’ was introduced with the meaning we use today in the 1830s by the French psychiatrist Jean-Étienne Esquirol, and from that point linked with psychiatric disorder, at least until recently. Hallucinations are still examples of mind-wandering, though, since they are produced in the mind, and are imposed as ‘extras’ on present reality. They are most simply defined as perceptions of things that are not there, most commonly as visions or voices, but occasionally through other senses, such as smell or touch. Macbeth’s third apparition was both seen and heard, unlike children of the Victorian era who were supposed to be seen but not heard.

  Hallucinations are perceived as though they are real, but differ from perceptions of reality in that they are not perceived by anyone else. They are not like normal memories of past events or your everyday mind-wanderings since they take place in the here and now. Where our normal mental time travels tend to be indistinct and contained within the mind, hallucinations are projected onto external space, with the vividness of reality. Sometimes, hallucinations do interact with real-world perception, superimposing unreal events onto an otherwise normal world. In his 2012 book Hallucinations, Oliver Sacks gives the example of looking at someone in front of you and seeing not just one person, but five identical people in a row.

  Hallucinations can seem so realistic that they are often incorporated into normal routine. Sacks tells of a hallucination he experienced while under the influence of hallucinatory drugs. He heard his friends Jim and Kathy knock on his door, and called out to welcome them into the living room, and chatted with them while he cooked them ham and eggs. When the meal was ready he put it on a tray and walked into the living room. There was no one there. The conversation had seemed entirely normal, with Jim and Kathy speaking in their normal voices, but the episode was a hallucination.

  Although the great majority of hallucinations are seen or heard, they sometimes inhabit other senses. William James writes of a close friend who had a vivid experience of being touched on the arm so realistically that he searched the room for an intruder. More elusive is what James described as a ‘sense of a presence’, the feeling that there is another person in the room. Although not impinging on the actual senses, the ghostly intruder may be felt to be facing in a particular direction, and even located in a particular spot. Hallucinations of this kind may well be interpreted as the presence of God.

  Hallucinations have often been taken to indicate mental disorder, with auditory hallucinations at one time suggesting referral to the psychiatrist and visual hallucinations to the neurologist. In 1973, eight people without psychiatric symptoms conducted an interesting experiment. They presented themselves at various hospitals in the United States, and complained, falsely, that they ‘heard voices’. Although they acted normally in other respects, they were diagnosed with mental illness, seven with schizophrenia and one with manic-depressive psychosis, and were admitted to psychiatric wards. Needless to say, they were eventually released to tell the tale. This is another example of the logical error of confirming the consequent. People with psychiatric disorders may indeed be prone to hallucinations, but hearing voices that are not there need not imply psychosis. Indeed, the majority of people who hear voices are not psychotic. Some people go out of their way to experience hallucinations, perhaps s
imply for pleasure, or in the belief that they enhance creativity. The Bohemian writer René Karl Wilhelm Johann Josef Maria Rilke (better known as Rainer Maria Rilke) waited years for the Voice to speak so he could transcribe what it said, a delay perhaps caused by the Voice struggling to address Rilke’s surfeit of names.

  Until Esquirol’s pronouncements in the eighteenth century, hearing voices was regarded as quite normal, and attributed to gods or demons. Even in more recent times, voices are sometimes heard as messages or commands from God, occasionally leading to religious conversion. One case, quoted by William James in his Varieties of Religious Experience, was George Fox, founder of the Quaker religion. He happened to be walking with friends near the cathedral city of Lichfield in England, when he was called:

  Immediately the word of the Lord came to me, that I must go thither. Being come to the house we were going to, I wished the friends to walk into the house, saying nothing to them of whither I was to go. As soon as they were gone I stept away, and went by my eye over hedge and ditch till I came within a mile of Lichfield where, in a great field, shepherds were keeping their sheep. Then was I commanded by the Lord to pull off my shoes. I stood still, for it was winter: but the word of the Lord was like a fire in me.

  Such voices, it has been suggested, may be a lingering relic of an ancient era when people paid much more attention to the voices of the gods than most of us do today.

  Bicameral minds

  Julian Jaynes, in his best-selling book The Origin of Consciousness in the Breakdown of the Bicameral Mind, published in 1976 but still in print, argued that up until around 1000 BC, or earlier, people were effectively controlled by hallucinations, interpreted as the gods issuing commands. Jaynes finds evidence for this in the ancient Greek epic the Iliad, set during the Trojan War in the twelfth century BC. It was maintained in oral traditions until eventually written down, supposedly by Homer, around 850 BC. People are described in the Iliad as though having no sense of conscious self; there is no first-person narrative. As Jaynes puts it: ‘the gods take the place of consciousness’. He goes on to write of the ‘bicameral mind’, divided between gods who give instructions and the person who hears them. ‘[I]t is highly probable’, he writes, ‘that the bicameral voices of antiquity were in quality very like such auditory hallucinations in contemporary people. They are heard by many completely normal people to varying degrees.’

  The bicameral mind began to break down as a result of catastrophic events in the second millennium BC. Wars, floods and migrations meant that ‘chaos darkened the holy brightnesses of the unconscious world’. The transition from passive reliance on the voices of the gods gradually gave way to individual responsibility for action. According to Jaynes, the shift is strikingly evident in the Odyssey, sequel to the Iliad, and also attributed to Homer, but very different in style and in depiction of the mind. In the Odyssey, the dominance of the gods recedes, and the characters become capable of making their own decisions. They speak in the first person.

  Jaynes also suggests that the shift is accompanied by a switch in brain dominance. In the bicameral mind, it was the right side of the brain that received the voices of the gods and relayed them to the left side, which is specialised for language and so ‘hears’ and obeys what the gods are saying. With the breakdown of the bicameral mind, dominance flipped to the left side, which now asserts control over action. Even so, hallucinations still persist, with reduced frequency, as vestigial functioning of the right brain.

  Jaynes died in 1997 but remains something of a cult figure. Whether his theory makes historical or neurological sense is doubtful. The time gap between the Iliad and the Odyssey, whether in terms of the events they depict or the times at which they were written, seems too narrow for such epochal changes. Jaynes’ account is based on events that were geographically constrained even by ancient standards—what of the populations of Asia, the Americas, Australia? Differences between the two sides of the brain have populist appeal, but are often more to do with folklore than neurological fact. The right and left brains have become little more than convenient pegs on which to hang our polarities—emotion and reason, love and war, female and male, and in an ironic reversal the left and right of politics. And yet the left brain/right brain story continues, most recently in Iain McGilchrist’s remarkable book The Master and his Emissary, published in 2009, in which the right brain is the master and the left brain the mere emissary. McGilchrist argues that control should be transferred back from the left brain to the right—a return, perhaps, to the bicameral mind.

  But there could be some truth to the claim that hallucinations come mainly from the right brain.

  Electrical induction

  One way to induce hallucinatory or dream-like experiences is to open up the skull and apply weak electrical stimulation to the exposed brain. This is not recommended as a party game, but can prove useful as a preliminary to brain surgery. Wilder Penfield was a neurosurgeon who established the famed Montreal Neurological Institute, and pioneered the use of surgery to remove brain areas containing the sources of epileptic seizures. Prior to surgery, he often applied mild electrical stimulation to the exposed brain, so that he could gain a sense of which portions could be surgically removed. Patients are conscious and able to talk during brain operations, and if stimulating a particular region prevented a patient from talking, then that region was assumed critical to speech, and should not be excised. To Penfield’s surprise, though, the stimulation sometimes caused patients to report hallucinatory or dream-like experiences.

  These ‘experiential responses’, as Penfield called them, were always induced by stimulating the temporal lobe, never by stimulating the other lobes. The temporal lobes, as those very lobes may remind you, house the hippocampus on the inner surface, and are therefore critically involved in memory. The experiential responses often seemed to Penfield, and to the stimulated patients, like replays of earlier memories, leading Penfield to suggest that we store away in our brains much more than we can voluntarily recall—perhaps even that everything we experience is tucked away in our memory banks. This interpretation helped fuel the idea in psychotherapy that harmful memories are repressed, and need to be coaxed out of the brain for therapy. As I suggested in Chapter 2, this notion can be dangerous, sometimes leading to false memories being unwittingly implanted by overzealous therapists.

  The alternative interpretation is that the experiential responses were more like dreams, or hallucinations, than replays of the past. One woman patient claimed she saw herself in childbirth, and felt as though she were reliving it. A twelve-year-old boy said he saw robbers coming at him with guns, a vision which Penfield suggested came from his reading of comics. A 45-year-old woman saw the faces of two former schoolteachers, who moved toward her and crowded her, and she cried out in terror. A fourteen-year-old girl saw herself as a seven-year-old walking through a field of grass and sensing that a man was behind her, about to smother her or hit her on the head. This last experience resembled a dream that she had had at age seven in which she was walking through a field with her brothers when a man approached from behind and asked how she would like to get into his bag with the snakes and be carried away. These experiences seem more like simulated threats than replays of actual events.

  In many cases the patients heard the voices of people they knew, or familiar tunes, but there was little indication that these were exact replays. When asked whether hallucinated episodes had actually occurred at some earlier period in their lives, some patients replied that they thought they might have, but there was little suggestion of certainty. Some hallucinations were nevertheless vivid and detailed, as in the following from a 26-year-old woman:

  She had the same flash-back several times. These had to do with her cousin’s house or the trip there—a trip she has not made for ten to fifteen years but used to make often as a child. She is in a motor car which had stopped before a railway crossing. The details are vivid. She can see the swinging light at the crossing. The train is goin
g by—it is pulled by a locomotive passing from the left to right and she sees coal smoke coming out of the engine and flowing back over the train. On her right there is a big chemical plant and she remembers smelling the odour of the chemical plant.

  The windows of the automobile seem to be down and she seems to be sitting on the right side and in the back. She sees the chemical plant as a big building with a half fence next to the road. There is a large flat parking space. The plant is a big rambling building—no definite shape to it. There are many windows.

  Even in this case, though, she says she doesn’t know whether this was a replay of an actual event, but she sees it as though it was. What seems more likely is that it was a montage built from elements of memory.

  All of these patients had histories of epilepsy, and some of the experiences also occurred during seizures, while others appeared only during brain stimulation. Roughly equal numbers of patients were operated for left- and right-temporal lobe epilepsy, but only 40 out of 520 had hallucinations induced electrically. In 25 of the 40, the epilepsy was focused in the non-dominant side of the brain—in most cases the right side. This does give some support to Jaynes’ idea that it’s the right brain that harbours hallucinations, although it was mainly the visual hallucinations that favoured the right brain, with auditory hallucinations as often from left as from the right. When speaking, at least, it seems that Jaynes’ gods may have visited through either side.

  These hallucinatory experiences no doubt draw on memory, and activation of the hippocampus surely played a major role. But this is not to say they replayed memories as they actually occurred. More often, they seem to be formed from elements of remembered places, people, or things, but constructed in ways that need bear little relation to earlier happenings, and indeed are often manifest in bizarre ways that could not possibly have actually happened. They are more like dreams than the mental time travels of our normal lives, and even those are in part fabricated. We probably never remember things precisely as they actually happened.