Joint engagement modulates object discrimination in toddlers: a pilot electrophysiological investigation.

Joint engagement (JE) is a state in which two people attend to a common target. By supporting an infant's attention to the target, JE promotes encoding of information. This process has not been studied in toddlers despite the fact that language and social interaction develop rapidly in this period. We asked whether JE modulates object discrimination in typically developing toddlers. In a pilot evaluation of a novel, naturalistic paradigm, toddlers (n = 11) were introduced to toys by an examiner with or without JE. Toddlers then viewed images of the toys while high-density electroencephalography (EEG) was recorded. Analysis focused on the differential neural response to objects presented in the two conditions. EEG components of interest included frontal positive component (Pb), negative component (Nc), and positive slow wave. Toddlers discriminated between conditions with a larger Pb peak amplitude to stimuli presented with JE and a larger Nc mean amplitude to the stimuli presented without JE, reflecting greater familiarity with the toys presented socially. Our findings suggest that JE supports object learning in toddlers, and supports the potential utility of this novel paradigm in both the assessment and the potential to detect impairment in social learning among toddlers.