Publications of Ernő Téglás

Can infants adopt underspecified contents into attributed beliefs? Representational prerequisites of theory of mind

Recent evidence suggests that young infants, as well as nonhuman apes, can anticipate others' behavior based on their false beliefs. While such behaviors have been proposed to be accounted by simple associations between agents, objects, and locations, human adults are undoubtedly endowed with sophisticated theory of mind abilities. For example, they can attribute mental contents about abstract or non-existing entities, or beliefs whose content is poorly specified. While such endeavors may be human specific, it is unclear whether the representational apparatus that allows for encoding such beliefs is present early in development. In four experiments we asked whether 15-month-old infants are able to attribute beliefs with underspecified content, update their content later, and maintain attributed beliefs that are unknown to be true or false. In Experiment 1, infants observed as an agent hid an object to an unspecified location. This location was later revealed in the absence or presence of the agent, and the object was then hidden again to an unspecified location. Then the infants could search for the object while the agent was away. Their search was biased to the revealed location (that could be represented as the potential content of the agent's belief when she had not witnessed the re-hiding), suggesting that they (1) first attributed an underspecified belief to the agent, (2) later updated the content of this belief, and (3) were primed by this content in their own action even though its validity was unknown. This priming effect was absent when the agent witnessed the re-hiding of the object, and thus her belief about the earlier location of the object did not have to be sustained. The same effect was observed when infants searched for a different toy (Experiment 2) or when an additional spatial transformation was introduced (Experiment 4), but not when the spatial transformation disrupted belief updating (Experiment 3). These data suggest that infants' representational apparatus is prepared to efficiently track other agents' beliefs online, encode underspecified beliefs and define their content later, possibly reflecting a crucial characteristic of mature theory of mind: using a metarepresentational format for ascribed beliefs.

Infants recruit logic to learn about the social world

When perceptually available information is scant, we can leverage logical connections among hypotheses to draw reliable conclusions that guide our reasoning and learning. We investigate whether this function of logical reasoning is present in infancy and aid understanding and learning about the social environment. In our task, infants watch reaching actions directed toward a hidden object whose identity is ambiguous between two alternatives and has to be inferred by elimination. Here we show that infants apply a disjunctive inference to identify the hidden object and use this logical conclusion to assess the consistency of the actions with a preference previously demonstrated by the agent and, importantly, also to acquire new knowledge regarding the preferences of the observed actor. These findings suggest that, early in life, preverbal logical reasoning functions as a reliable source of evidence that can support learning by offering a logical route for knowledge acquisition.

Seeing behind the surface: communicative demonstration boosts category disambiguation in 12-month-olds

In their first years, infants acquire an incredible amount of information regarding the objects present in their environment. While often it is not clear what specific information should be prioritized in encoding from the many characteristics of an object, different types of object representations facilitate different types of generalizations. We tested the hypotheses that 1-year-old infants distinctively represent familiar objects as exemplars of their kind, and that ostensive communication plays a role in determining kind membership for ambiguous objects. In the training phase of our experiment, infants were exposed to movies displaying an agent sorting objects from two categories (cups and plates) into two locations (left or right). Afterwards, different groups of infants saw either an ostensive or a non-ostensive demonstration performed by the agent, revealing that a new object that looked like a plate can be transformed into a cup. A third group of infants experienced no demonstration regarding the new object. During test, infants were presented with the ambiguous object in the plate format, and we measured generalization by coding anticipatory looks to the plate or the cup side. While infants looked equally often towards the two sides when the demonstration was non-ostensive, and more often to the plate side when there was no demonstration, they performed more anticipatory eye movements to the cup side when the demonstration was ostensive. Thus, ostensive demonstration likely highlighted the hidden dispositional properties of the target object as kind-relevant, guiding infants’ categorization of the foldable cup as a cup, despite it looking like a plate. These results suggest that infants likely encode familiar objects as exemplars of their kind and that ostensive communication can play a crucial role in disambiguating what kind an object belongs to, even when this requires disregarding salient surface features.