2023-06-23 18:15:59
In the same way as human beings, chimpanzees would be able to consider two scenarios and prepare to achieve a goal, as demonstrated by a first experiment published this week in the journal Biology Letters, of the Royal Society, in the United Kingdom.
The so-called “modal reasoning” is, in theory, an exclusive prerogative of the human brain. It allows one to imagine, or consider, what could have happened under certain conditions, such as, for example, regretting having left the house without an umbrella before it started to rain, or having taken it just in case. storm arrives.
Scientists believed that this reasoning faculty, which appears only after infancy and requires the acquisition of language, was unique to humans. The researchers found, however, that chimpanzees can reason logically when faced with a situation that involves a choice.
Modal reasoning “is the basis of our imagination,” explains Jan Engelmann, assistant professor of psychology at the American University of Berkeley, in conversation with AFP.
According to Engelmann, lead author of the study published on Wednesday, “chimpanzees can represent alternative possibilities, that is, imagine possible outcomes” for a given situation.
The researcher began studying this phenomenon last year, observing the reaction of a chimpanzee to a worker, depending on whether or not the latter had the option of giving him the expected reward.
The chimpanzee did not get irritated with the person participating in the experiment for not fulfilling his wish when it did not depend on him, but when he did not.
This time, with his colleagues from universities in the UK, Austria and Germany, Engelmann wanted to know if a chimpanzee could imagine and prepare for a scenario with two possible outcomes.
– Risk of losing –
The device used is inspired by an experiment, in which a chimpanzee was in front of an inverted “Y” shaped tube. In it, the researcher left a reward. The experiment questioned the monkey’s ability to consider the two possible outcomes and place its hand under the two exits of the tube.
But it seems that “this behavior does not come naturally to the chimpanzee”, according to Engelmann.
To remedy this, this time the chimpanzee was confronted with a somewhat similar device, but in which it was placed “in competition” with the experimenter. According to the researchers, this competition stimulates the cognitive activity of this primate.
The reward is no longer released through a tube, but is found on the tray of a scale located under each of the tubes, which, in this case, can be two vertical ones, or one in the shape of an inverted Y.
In each case, the experimenter drops a rock onto a rocking tray placed under the tubes.
The reward then always goes his way, leaving the chimpanzee with nothing—unless the monkey uses his hand to move the tray to his side when the stone falls.
The experiment showed that, statistically, the chimpanzee blocked both sides of the scale more when the stone was thrown into an inverted Y tube. That is, the animal realized that, in this scenario, it ran a greater risk of losing than when faced with two vertical tubes, a situation in which it could more easily know where the stone would fall.
The animal was able to anticipate the setting in which it would be deprived of the reward.
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