ISLI: Integrating Social Reasoning and Logical Reasoning

October, 2021 to September, 2023
EU Horizon 2020 - Marie Skłodowska-Curie actions / Individual fellowships

How Do Infants Reason about the World and their Social Partners?

We need to reason about what we do not directly observe, such as possible but non-actual outcomes or others’ intangible mental states. However, the development of these reasoning abilities is not well understood. The EU-funded ISLI project aims to study the representations and processes that underlie infant reasoning and their similarity to adult reasoning. The project will investigate how infants eliminate unlikely or impossible alternatives from consideration and whether infants attribute complex beliefs to others about such eliminated outcomes. It will also explore whether infants are subject to the same reasoning errors that adults can fall victim to. Ultimately, these findings will provide insight into the extent of infants’ early reasoning abilities and how they are linked across domains.


Infants reason about their world and social partners in rather sophisticated ways. What underlies this early reasoning capacity? Is it the symbolic representations that support adult abstract combinatorial thought and language? Do infants possess logical operators such as negation and language-like structures such as recursive propositions? This project addresses these questions. In the first line of research, I investigate how infants reason about alternatives. When shown that an alternative is impossible, infants avoid it, pursuing others instead. In Study 1, I ask whether infants’ elimination of alternatives is based on the logical operator negation, which is diagnostic of abstract and symbolic combination in thought. In the second and third lines, I use social contexts to further investigate infant reasoning. Study 2 extends paradigms used to test 1st order attribution of false beliefs about objects. By modifying aspects of the social context, I ask whether infants are able to make 2nd order attributions of false beliefs about beliefs (i.e. she thinks that he thinks…). Importantly, such attributions necessarily take a recursive propositional structure. In Study 3, I ask if social reasoning can be detrimental to infant and even adult logical reasoning. Adults commit reasoning errors and social information (such as inferences about others’ communicative intentions) may give rise to these errors. This study uses communicative and non-communicative contexts to (i) test whether social information gives rise to errors in adults and (ii) determine whether similar errors occur in infancy. Together, these three lines of research illuminate the nature of infant reasoning and its similarity to adult reasoning. Are infants also victim to reasoning errors? Is infant reasoning nevertheless based on symbolic and language-like combinatorial structures? Ultimately, these findings will provide insight into the relationship between infant thought and later language acquisition.