Читать книгу The Secret Life of the Mind: How Our Brain Thinks, Feels and Decides - Mariano Sigman - Страница 31

Until now we’ve talked about decision-making processes as if they were all of one class, governed by the same principles and carried out in the brain by similar circuits. However, we all perceive that the decisions we make belong to at least two qualitatively distinct types; some are rational and we can put forward the arguments behind them. Others are hunches, inexplicable decisions that feel as if they are dictated by our bodies. But are there really two different ways of deciding? Is it better to choose something based on our intuitions, or to carefully and rationally deliberate each decision?

In general we associate rationality with science, while the nature of our emotions seems mysterious, esoteric and essentially inexplicable. We will topple this myth with a simple experiment.

Two neuroscientists, Lionel Naccache and Stanislas Dehaene – my mentor in Paris – did an experiment in which they flashed numbers on screens so fleetingly that the participants believed they’d seen nothing. This type of presentation, which doesn’t activate consciousness, is called subliminal. Then they ask the participants to say if the number is higher or lower than five and, much to their own surprise, they answer correctly in most cases. The person making the decision perceives it as a hunch, but from the experimenter’s perspective it is clear that the decision was induced unconsciously with a mechanism very similar to that of conscious decision-making.

Which is to say that, in the brain, hunches aren’t so different from rational decisions. But the previous example doesn’t capture all the richness of the physiology of unconscious decisions. In this case, popular expressions such as ‘trust your heart’ or ‘go with your gut feelings’ turn out to be quite accurate and shed light on how intuitions are forged.

All it takes to understand this is putting a pencil between your teeth, lengthwise. Inevitably, your lips will rise in an imitation of a smile. This is obviously a mechanical effect, not a reflection of an emotion. But that doesn’t matter, it still gives a certain sense of wellbeing. The mere gesture of the smile is enough. A film scene will seem more entertaining to us if we watch it with a pencil held in our mouth that way than if we hold it between our lips, as if scowling. So, deciding whether something is fun or boring does not only originate in an evaluation of the external world, but in visceral reactions produced in our internal worlds. Crying, sweating, trembling, increasing heart rate or secreting adrenaline are not merely reactions by the body to communicate an emotion. Instead, the brain reads and identifies these bodily variables to encode and produce feelings and emotions.

That corporeal states can affect our decision-making process is a physiological and scientific demonstration of what we perceive as a hunch. When making a decision unconsciously, the cerebral cortex evaluates different alternatives and, in doing so, estimates the possible risks and benefits of each option. The result of this computation is expressed in corporeal states through which the brain can recognize risk, danger or pleasure. The body becomes a reflection and a resonating chamber of the external world.