Our ability to use complex communication through symbols, such as language, is thought to be at the core of mankind's superior reasoning. But a new study which followed one-year-old babies found that they were able to reason by process of elimination well before they could articulate anything more meaningful than "goo goo ga ga." It follows that language and higher reasoning are not as intertwined as scientists used to think.
A logical tiny human
Psychologists at Johns Hopkins University studied 48 infants aged 12 to 18 months. The babies looked at a very simple animation which showed two objects: a flower and a dinosaur. After the babies were given the time to study the two objects, a barrier was raised in the animation, which obstructed the objects from view. An all-powerful cup then scooped the dinosaur from behind the curtain (the infants can see the dinosaur being scooped).
What happened next depended on whether the infants were classed in one of two groups. In the first group, when the barrier was raised, the remaining object was the flower, as should logically be the case. In the second group, lifting the barrier perplexingly revealed no flower but another dinosaur.
Because the infants are not able to articulate their thoughts, the John Hopkins researchers used eye-tracking to infer what was on the children minds. When the barrier was raised and the dinosaur showed, the infant's gaze lingered significantly longer on the scene with the second dinosaur. This implies that they can sense that something is not at all expected -- they're confused, as any adult would be.
One of the most important logical building blocks of higher reasoning is the ability to imagine multiple outcomes and to eliminate those that are inconsistent. Scientists formally call this process disjunctive syllogism. For instance, if only A or B is true, and A is false, then the only possible outcome is that B is true. It sounds very simple but, fundamentally speaking, this is a hugely powerful ability, which most creatures lack.
Intuitively, the findings make sense. When we reason, we silently do so by talking to ourselves. The findings show that preverbal infants work much in the same way, using the same type of serial reasoning, way before any meaningful language abilities had developed. Previously, psychologists at Emory University and Bucknell University determined that infants are capable of deductive problem solving as early as 10 months of age.
"We found that within the first year of life, children can engage in this type of logical reasoning, which was previously thought to be beyond their reach until the age of about four or five years," says Stella Lourenco, the Emory University psychologist who led the 2015 study.
Not too long ago, infants were thought to be incapable of higher cognitive functions. Up until the in 1970s, the prevailing philosophy in cognitive psychology was that children younger than seven were mostly illogical and incapable of transitive inference -- the ability to deduce that if Item B is related to Item C and Item C is related to Item D, then Item B must be related to Item D. But just because they can't articulate, that doesn't mean infants aren't capable of reasoning. On a practical level, the findings could one day lead to new techniques that diagnose cognitive disabilities early on. In the long term, this sort of research will inspire more work that might reveal what the very youngest humans think.
"It’s about launching a whole body of work that’s going to emerge over the coming decade,” said Justin Halberda, a psychologist at John Hopkins, who was not involved in the study but wrote an accompanying analysis in about the new paper published in Science. “It’s an invitation," he told The Verge.