Infants accept arbitrary objects as ad-hoc symbols

The ability to process visual objects as symbols is fundamental to the interpretation of depictions such as maps, graphs, diagrams, and animations. We outline a cognitive mechanism that may underlie the interpretation of depictions and present three eye-tracking and looking-time experiments (n = 192) indicating that this ability is already in place in 15-month-old infants. Experiment 1 showed that infants can assign arbitrary shapes (e.g., a triangle) to familiar discourse referents (e.g., a duck) based on labeling (e.g., “Look, a duck!”). Experiment 2 showed that infants do not generalize these mappings to a new speaker. This rules out the alternative hypothesis that infants interpret such labeling events literally. Experiment 3 revealed that infants are sensitive to the conceptual identity of the referent. After being told that one shape stands for an agent (e.g., a duck) and another for a object (e.g., a cup), infants distinguished congruent trials, in which the agent symbol moved towards the object symbol, from incongruent trials with the opposite movement pattern. This rules out the alternative hypothesis that infants interpret the labeling events as referential pacts. To our knowledge, this is the earliest evidence for a general symbol concept in infancy. This concept underlies the ability to use arbitrary objects to communicate and may constitute a foundational element of human cognition.