Language is a key thinking tool, which is the basis of our unique ability to reason. However, a recent study suggests that this ability to think logically does not really depend on our ability to express ourselves verbally, at least not completely. Babies who are still too young to speak can indeed reason and make rational deductions.
In this study published in the journal Science, researchers from several European institutions studied infants aged 12 and 19 months. It is at this age that babies began to learn how to speak. The children had to inspect separate objects here several times: a dinosaur and a flower. The objects were initially hidden behind a black panel, and the idea was to pick up the dinosaur. Half the time, the panel was then removed to reveal – as expected – the remaining flower. In the rest of the cases however, the wall disappeared and a second dinosaur was presented to the babies.
Regarding this second scenario, the children inferred that something was wrong – even if they were unable to express it verbally. The researchers here relied on the technique of eye-tracking, commonly used to assess mental abilities in young children and in monkeys. The children were indeed looking at the unexpected objects longer and more significantly when they arose, suggesting that they were confused by the revelation. “Our results indicate that the acquisition of logical vocabulary might not be the source of the most basic logical elements in the mind,” says Nicoló Cesana-Arlotti, senior researcher at Johns Hopkins University. He notes in passing that a major component of human logic is related to the reflection on alternative possibilities and the elimination of incompatibilities.
As part of their study, the researchers also reported that infants’ pupils dilated when they watched animations with illogical results. The same phenomenon occurs in adults facing problems of logic. Thus, babies would be well aware of how things “should” be, even before they can express it verbally.
“To our knowledge, no one has ever directly documented the logical reasoning in 12-month-old infants,” he adds. “Exploring the initial state of logic in the mind is a very exciting undertaking.”