Infant research uncovers development of human reasoning
Human rationality implies that our actions largely correspond with our beliefs, and that our beliefs are in line with our reasoning. For example, a rational consumer might choose to purchase organic, locally grown produce even if it is more expensive, because of their environmental convictions. How humans develop rational thinking however remains a contentious issue. Testing the development of our reasoning capacity as infants might help us to better understand how we construct the building blocks of adult reasoning. “In the first few years of life, infants face a variety of situations they have never experienced before,” explains PreLog project coordinator Ernő Téglás from Central European University in Hungary. “Just as science depends on our ability to reason logically, we argued that even very simple forms of logical inferences may boost early problem-solving, and guide reasoning and learning.”
Rationality in infants
The PreLog project, which was funded by the European Research Council, sought to explore the origins of human rationality by analysing the nature of preverbal infants’ inferential abilities. To begin, the project set out to identify what are called logical primitives in infants. The project team wanted to understand the function that these early logical concepts might play in the development of reasoning. To study these questions, they often relied on new techniques. For instance, the project conducted pupillometric studies, exploring infants’ pupil dilation in response to various stimuli. “While pupillometry is well-established in adult research, it is a relatively new technique in infant experiments,” adds Téglás. In one study infants were presented with simple video animations. Three different objects with identical top parts moved behind screens. When the target object emerged to reveal only its top part, this was compatible with a varying number of possible identities. Téglás and his team demonstrated that 14-month-olds were able to represent multiple alternative possibilities at the same time. This supports the theory that the preconditions for disjunctive inferences are present at an early age. “Ambiguous objects that were compatible with multiple possible identities triggered larger pupil dilation,” he says. “This new approach helped us to find perhaps the first indications of modal concepts before language.” Téglás and his team also documented early emerging logical capacities such as disjunctive inference, again using pupillometry and other techniques. Disjunctive inference is the means by which we eliminate alternatives, in the form of ‘A or B, not A, therefore B’. The project findings suggest that this important form of logical inference is part of a 12-month-old’s repertoire. “Importantly, our studies revealed a relatively flexible system,” says Téglás. “Inferences are supported by an architecture that can generate conclusions to be integrated with other processes.”
Origins of human reasoning
PreLog has played a pioneering role in better understanding the origins and development of human reasoning. According to Téglás, this work can be seen as part of a new emerging field in infant cognition research. “An increasing number of labs are investigating the foundations of logical abilities,” he notes. “In order to have a better understanding of the origins of compositional thought though, we need to be able to document developmental changes from infancy to adulthood.” For Téglás, this is the logical next step. “Investigating the presence of these abilities in non-human animals will also further fine-tune this picture,” he concludes. “Identifying the precursors of human logical abilities may reveal not only the building blocks of human rationality, but also the origins of biases and errors.”
Keywords
PreLog, verbal, infants, reasoning, rationality, cognition, pupillometric
