Visual category representations in the infant brain.

Visual categorization is a human core cognitive capacity1,2 that depends on the development of visual category representations in the infant brain.3,4,5,6,7 However, the exact nature of infant visual category representations and their relationship to the corresponding adult form remains unknown.8 Our results clarify the nature of visual category representations from electroencephalography (EEG) data in 6- to 8-month-old infants and their developmental trajectory toward adult maturity in the key characteristics of temporal dynamics,2,9 representational format,10,11,12 and spectral properties.13,14 Temporal dynamics change from slowly emerging, developing representations in infants to quickly emerging, complex representations in adults. Despite those differences, infants and adults already partly share visual category representations. The format of infants' representations is visual features of low to intermediate complexity, whereas adults' representations also encode high-complexity features. Theta band activity contributes to visual category representations in infants, and these representations are shifted to the alpha/beta band in adults. Together, we reveal the developmental neural basis of visual categorization in humans, show how information transmission channels change in development, and demonstrate the power of advanced multivariate analysis techniques in infant EEG research for theory building in developmental cognitive science.

The role of social signals in segmenting observed actions in 18-month-old children.

Learning about actions requires children to identify the boundaries of an action and its units. Whereas some action units are easily identified, parents can support children's action learning by adjusting the presentation and using social signals. However, currently, little is understood regarding how children use these signals to learn actions. In the current study, we investigate the possibility that communicative signals are a particularly suitable cue for segmenting events. We investigated this hypothesis by presenting 18-month-old children (N = 60) with short action sequences consisting of toy animals either hopping or sliding across a board into a house, but interrupting this two-step sequence either (a) using an ostensive signal as a segmentation cue, (b) using a non-ostensive segmentation cue and (c) without additional segmentation information between the actions. Marking the boundary using communicative signals increased children's imitation of the less salient sliding action. Imitation of the hopping action remained unaffected. Crucially, marking the boundary of both actions using a non-communicative control condition did not increase imitation of either action. Communicative signals might be particularly suitable in segmenting non-salient actions that would otherwise be perceived as part of another action or as non-intentional. These results provide evidence of the importance of ostensive signals at event boundaries in scaffolding children's learning.

Motor cortex activity during action observation predicts subsequent action imitation in human infants.

From early on, human infants acquire novel actions through observation and imitation. Yet, the neural mechanisms that underlie infants' action learning are not well understood. Here, we combine the assessment of infants' neural processes during the observation of novel actions on objects (i.e. transitive actions) and their subsequent imitation of those actions. Most importantly, we found that the 7-10 â€‹Hz motor cortex activity increased during action observation and predicted action imitation in 20-month-olds (n â€‹= â€‹36). 10-month-olds (n â€‹= â€‹42), who did not yet reliably imitate others' actions, showed a highly similar neural activity pattern during action observation. The presence or absence of communicative signals did neither affect infants' neural processing nor their subsequent imitation behavior. These findings provide first evidence for neural processes in the motor cortex that allow infants to acquire transitive actions from others ‒ and pinpoint a key learning mechanism in the developing brain of human infants.