Infants use behavioral and verbal cues to infer another person's action intention. However, it is still unclear how infants integrate these often co-occurring cues depending on the cues' coherence (i.e., the degree to which the cues provide coherent information about another's intention). This study investigated how 18- and 24-month-olds' (N = 88 per age group) action selection was influenced by varying the coherence of a model's verbal and behavioral cues. Using a between-subjects design, infants received six trials with different stimulus objects. In the conditions Congruent, Incongruent, and Failed-attempt, the model uttered a telic verb particle that was followed by a matching or contradicting goal-directed action demonstration, or by a non goal-directed slipping motion, respectively. In the condition Pseudo-word, a nonsense word was combined with a goal-directed action demonstration. Infants' action selection indicated an adherence to the verbal cue in Congruent, Incongruent, and Failed-attempt, and this was stronger in 24- than 18-month-olds. Additionally, in Incongruent and Failed-attempt, patterns of cue integration across the six trials varied in the two age groups. Regarding the behavioral cue, infants in Congruent and Pseudo-word preferentially followed this cue in both age groups, which also suggested a rather unspecific effect of the verbal cue in Congruent. Relatively longer first action-latencies in Incongruent and Failed-attempt implied that these types of coherence elicited higher cognitive demands than in Congruent and Pseudo-word. Results are discussed in light of infants' flexibility in using social cues, depending on the cue's coherence and on age-related social-cognitive differences.
Keywords: Action; Imitation; Infancy; Social cues; Social learning; Verbs.
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