Infant dominant rhythm desynchronization to faces and objects.

Infants' electroencephalography (EEG) dominant rhythm oscillates between 6 and 9 Hz. The desynchronization of this rhythm from baseline to the processing of visual stimuli is used as an index to better understand the development of visual attention. However, development trajectories of desynchronization remain underexplored. Additionally, it is unclear whether development of desynchronization is sensitive to task demands or if it reflects broader developmental changes. To investigate these questions, EEG data were collected from infants aged 6, 9, and 12 months while they passively viewed a fixation cross followed by 10-s trials of a female face or novel object tracked down the screen. Dominant rhythm desynchronization was calculated by subtracting power during the fixation period from power during each task condition. The results revealed significant desynchronization in response to faces at occipital electrodes for all age groups. The magnitude of the desynchronization also increased from 6 to 9 to 12 months of age in response to faces over right occipital electrodes. No significant desynchronization was observed for object stimuli. These findings suggest that dominant rhythm desynchronization develops across infancy and is sensitive to stimulus type. The increased desynchronization for faces compared to objects highlights infants' general preference for faces relative to objects.