Novel word disambiguation via mutual exclusivity is the tendency to discard familiar objects as referents of novel words. While mutual-exclusivity inferences have been widely documented in toddlers beyond 18 months of age, studies typically failed to show it in younger infants. Recently, Pomiechowska, Brody, Csibra, and Gliga (2021) showed that 12-month-old infants can use mutual exclusivity, but only if familiar objects are targeted by non-verbal communication (i.e., pointing) prior to labeling. This arguably triggers infants to represent these objects under a conceptual description, a representational format that is necessary for mutual exclusivity inferences but is not spontaneously generated in young infants. The present study is a direct online replication of the task used by Pomiechowska et al. with a wider age range (12-15 months) and adapted for Zoom-based testing.

Humans routinely monitor social interactions to learn about the relational make-up of their groups and select social partners. It is unclear however whether social interactions primarily invite inferences about the dispositions of the participants involved or about underlying social relations. In the present study we tested which of these two inferences children and adults draw when observing interactions based on dominance. Children expected dominants to prevail over previous subordinates but did not generalize this expectation to interactions with novel agents, whereas adults did. These results suggest that children interpreted dominance as specific to a particular social relation, whereas adults interpreted it as a stable, target-invariant trait. This asymmetry supports the proposal that children may first interpret social interactions through a relational stance, and only later in development apprehend them through the lenses of trait attribution.

Across three experiments, we show that 15-month-old infants understand that arbitrary objects can be used as symbols. Experiment 1 shows that infants map geometric shapes (e.g., a triangle) onto familiar discourse referents (e.g., a duck) based on labeling (e.g., “Look, a duck!”). Experiment 2 shows that infants do not generalize these mappings to a new speaker. This rules out the alternative hypothesis that infants interpret the labeling events literally. Experiment 3 shows that infants are sensitive to the conceptual identity of the discourse referent. After being told that one shape represents an agent (e.g., a duck) and another shape represents a patient (e.g., a cup), infants attend differentially when the agent symbol moves towards the patient symbol than the opposite. This rules out the alternative hypothesis that infants interpret the labeling events as referential pacts. The findings jointly indicate that symbolic relations are easily activated and available early in human development.

We test for infants’ proposed altercentric learning bias (Southgate, 2020). By tracking others’ attention, infants build their own models of the environment based on the well developed models of the adults. If true, an event will be better remembered if witnessed together with someone else than if attended alone. Eight-month-old-infants (6 conditions, n = 32/group) saw an object being hidden first in one, then in another location. At the end of each trial, one of the locations was revealed, always empty. Participants correctly remembered the location and looked longer if it was empty (conditions 1-2). When an agent attends the first hiding but not the second, infants misremember the object in the first location (condition 3), providing initial evidence for the altercentric bias. Contrary to our predictions, when the agent only attends to the last hiding location, or both, infants have no expectation of the object’s whereabouts (conditions 4-6).