Opinion – Luciano Melo: Optimism and pessimism, a history of the cerebral hemispheres

Symmetry was considered an item of perfection. The effectiveness of the human brain was the mirror of two symmetrically arranged hemispheres.

At the time it did not go unnoticed that most people were right-handed, but this fact was overlooked. In 1820, Gottfried Treviranus, physician and founder of biology, broke with the careless consensus: “Humans have multiple deep convolutions asymmetrically organized in two hemispheres. This is different from the brains of apes.”

The discrepancies of shapes between the brain halves cause cognitive advancement, the apex of which is in us. Complementary information is computed in parallel in the cerebral hemispheres, not in convergence. In this way redundancy is reduced, and performance is favored.

Vertebrates whose brains operate in asymmetry are at an advantage. Small birds use one hemisphere to forage for food, while another hemisphere looks out for security. The specialization of hemispheres is an evolutionary heritage. Natural selection pressured early primates to use more of the right-hand abilities controlled by the left hemisphere. Another task allocated preferentially in the left hemisphere is language.

But there’s more: the fundamental approach to life comes asymmetrical. Under normal circumstances, the two brain hemispheres share information to unify our perceptions of ourselves and the environment, cohesive consciousness. However, extreme conditions that amplify, or reduce, the performance of a hemisphere can modulate pessimism and optimism. Pessimistic views are generally held by the right hemisphere, while optimistic thoughts are primarily supported by the left hemisphere.

Eye-tracking studies showed that optimists looked at negative images less than pessimists. For the glass half-full or half-empty example, they will look at the liquid. In one experiment, volunteers were shown photographs of unpleasant images while their brains were scanned by functional magnetic resonance imaging.

Participants were asked to imagine a positive outcome for the scenes photographed. For example, in response to an image of an automobile accident, participants could imagine that everything was scenographic, for a good movie. The “positive thinking” strategies were matched by greater physiological activity in the left hemisphere.

Pessimists tend to believe that events in their lives are controlled by external forces, they see themselves as relatively passive agents. Success and achievements occur, according to them, mainly by luck, chance or proximity to powerful people or institutions. In this sense, the probability of a person succeeding by his own actions and efforts is very low.

In contrast, optimists see themselves as active agents, feel in control of their destinies, and trust their ability to influence the environment. Epileptic patients whose seizures stem from damage to the left hemisphere consider themselves more passive to the world and that their efforts less interfere with success than the circumstances. The opposite, if the damage is to the right hemisphere.

Optimistic or pessimistic feelings are not fixed. In one study, college students’ brain activity was recorded by electroencephalography while students listened to a radio message announcing tuition increases.

Half of the participants were informed that the decision was final. The other half were induced to believe they could reverse the decision if they signed a petition. This manipulation created a group of students who believed they had control over a negative situation, and this belief emerged in conjunction with increased left hemisphere activity.

The right hemisphere is relatively more involved in surveillance. It becomes more prepared to detect dangers and prepare the body to deal with threats. This special sensitivity is necessary for survival, but it has a downside; implies highlighting what can potentially go wrong. “Sees” more potential problems than potential opportunities.

The left hemisphere, by contrast, deals less with surveillance and more with interference strategies. The right hemisphere tells you that there is a forest in front of you, the left hemisphere tells you that there is a tree. The left hemisphere gives you hope to persist, even if the best alternative is to change strategy.

Inside the braincase, there is fluidity and contradictions. We can be pessimistic and optimistic at the same time about different issues in life. For example, we are simultaneously capable of thinking that we will be healthy and safe despite imprudence, but that we will not have a good year at work. Duality is in our brain, masked in momentary certainties. But convictions can narrow our point of view, inhibiting the balance of interhemispheric functions.