some patients with lesions in the ventromedial prefrontal cortex, who evidently can detect costs and benefits but seem indifferent as to their ratio.) In each case, addiction can be thought of as a particular case of a general problem: our species-wide difficulty in balancing ancestral and modern systems of self-control.
To be sure, other factors are at work, such as the amount of pleasure a given individual gets from a given activity; some people get a kick out of gambling, and others would rather just save their pennies. Different people are vulnerable to different addictions, and to different degrees. But we are all at least somewhat at risk. Once the balance between long-term and short was left to a rather unprincipled tug-of-war, humanity’s vulnerability to addiction may have become all but inevitable.
If the split in our systems of self-control represents one kind of fault line in the human mind, confirmation bias and motivated reasoning combine to form another: the relative ease with which humans can lose touch with reality. When we “lose it” or “blow things out of proportion,” we lose perspective, getting so angry, for example, that all traces of objectivity vanish. It’s not one of our virtues, but it is a part of being human; we are clearly a hotheaded species.
That said, most of the time, most of us get over it; we may lose touch in the course of an argument, but ultimately we take a deep breath or get a good night’s sleep, and move on. (“Yes, it was really lousy of you to stay out all night and not call, but I admit that when I said you
What occasionally allows normal people to spiral out of control is a witch’s brew of cognitive kluges: (1) the clumsy apparatus of self-control (which in the heat of the moment all too often gives the upper hand to our reflexive system); (2) the lunacy of confirmation bias (which convinces us that we are
That same mix, minus whatever inhibitory mechanisms normal people use to calm down, may exacerbate, or maybe even spawn, several other aspects of mental illness. Take, for example, the common symptom of paranoia. Once someone starts down that path — for whatever reason, legitimate or otherwise — the person may never leave it, because paranoia begets paranoia. As the old saying puts it, even the paranoid have real enemies; for an organism with confirmation bias and the will to deny counterevidence (that is, motivated reasoning), all that is necessary is one true enemy, if that. The paranoid person notices and recalls evidence that confirms his or her paranoia, discounts evidence that contradicts it, and the cycle repeats itself.
Depressives too often lose touch with reality, but in different ways. Depressives don’t generally hallucinate (as, for example, many schizophrenics do), but they often distort their perception of reality by fixating on the negative aspects of their lives — losses, mistakes, missed opportunities, and so forth — leading to what I call a “ruminative cycle,” one of the most common symptoms of depression. An early, well-publicized set of reports suggested that depressives are more realistic than happy people, but today a more considered view is that depressives are disordered in part because they place undue focus on negative things, often creating a downward spiral that is difficult to escape. Mark Twain once wrote, in a rare but perceptive moment of seriousness, “Nothing that grieves us can be called little; by the eternal laws of proportion a child’s loss of a doll and a king’s loss of a crown are events of the same size.” Much, if not all, depression may begin with the magnification of loss, which in turn may stem directly from the ways in which memory is driven by context. Sad memories stoke sadder memories, and those generate more that are sadder still. To a person who is depressed, every fresh insult confirms a fundamental view that life is unfair or not worth living. Contextual memory thus stokes the memory of past injustices. (Meanwhile, motivated reasoning often leads depressives to discount evidence that would contradict their general view about the sadness of life.) Without some measure of self-control or a capacity to shift focus, the cycle may persist.
Such feedback cycles may even contribute a bit to bipolar disorder, not only in the “down” moments but also even in the manic (“up”) phases. According to Kay Redfield Jamison, a top-notch psychologist who has herself battled manic depression, when one has bipolar disorder, there is a particular kind of pain, elation, loneliness, and terror involved in this kind of madness… When you’re high it’s tremendous. The ideas and feelings are fast and frequent like shooting stars… But, somewhere, this changes. The fast ideas are far too fast, and there are far too many; overwhelming confusion replaces clarity… madness carves its own reality.
Without sufficient inherent capacity for cognitive and emotional control, a bipolar person in a manic state may spiral upward so far that he or she loses touch with reality. Jamison writes that in one of her early manic episodes she found herself “in that glorious illusion of high summer days, gliding, flying, now and again lurching through cloud banks and ethers, past stars, and across fields of ice crystals… I remember singing ‘Fly Me to the Moon’ as I swept past those of Saturn, and thinking myself terribly funny. I saw and experienced that which had been only in dreams, or fitful fragments of aspiration.” Manic moods beget manic thoughts, and the spiral intensifies.
Even the delusions common to schizophrenia may be exacerbated by — though probably not initially caused by — the effects of motivated reasoning and contextual memory. Many a schizophrenic, for example, has come to believe that he is Jesus and has then constructed a whole world around that notion, presumably “enabled” in part by the twin forces of confirmation bias and motivated reasoning. The psychiatrist Milton Rokeach once brought together three such patients, each of whom believed himself to be the Son of the Holy Father. Rokeach’s initial hope was that the three would recognize the inconsistency in their beliefs and each in turn would be dissuaded from his own delusions. Instead, the three patients simply became agitated. Each worked harder than ever to preserve his own delusions; each developed a different set of rationalizations. In a species that combines contextually driven memory with confirmation bias and a strong need to construct coherent-seeming life narratives, losing touch with reality may well be an occupational hazard.
Depression (and perhaps bipolar disorder) is probably also aggravated by another one of evolution’s glitches: the degree to which we depend on the somewhat quirky apparatus of pleasure. As we saw in the previous chapter, long before sophisticated deliberative reasoning arose, our pre-hominid ancestors presumably set their goals primarily by following the compass of pleasure (and avoiding its antithesis, pain). Even though modern humans have more sophisticated machinery for setting goals, pleasure and plain probably still form the core of our goal-setting apparatus. In depressives, this may yield a kind of double-whammy; in addition to the immediate pain of depression, another symptom that often arises is paralysis. Why? Quite possibly because the internal compass of pleasure becomes nonresponsive, leaving sufferers with little motivation, nothing to steer toward. For an organism that kept its mood separate from its goals, the dysfunction often accompanying depression might simply not occur.
In short, many aspects of mental illness may be traced to, or at least intensified by, some of the quirks of our evolution: contextual memory, the distorting effects of confirmation bias and motivated reasoning, and the peculiar split in our systems of self-control. A fourth contributor may be our species’ thirst for explanation, which often leads us to build stories out of a sparse set of facts. Just as a gambler may seek to “explain” every roll of the dice, people afflicted with schizophrenia may use the cognitive machinery of explanation to piece together voices and delusions. This is not to say that people with disorders aren’t different from healthy folks, but rather that their disorders may well have their beginnings in neural vulnerabilities that we all share.
Perhaps it is no accident, then, that so much of the advice given by cognitive-behavioral therapists for treating depression consists of getting people to cope with ordinary human failures in reasoning. David Burns’s well-known
I don’t mean to say that depression (or any disorder) is purely a byproduct of limitations in our abilities to objectively evaluate data, but the clumsy mechanics of our klugey mind very likely lay some of the shaky groundwork.
