At 4 months of age, children are able to categorize human faces at a glance. However, the neural mechanisms behind building distinct categories remain disputed. It has been suggested that the combined information of multisensory input early in life is advantageous to forming categories in context and benefits perceptual development.
The current study focuses on the auditory domain by providing participants with infant- or adult-directed speech during visual stimulation. Beyond the finding that children prefer infant-directed speech (IDS), neurobehavioral studies suggest that specific neural mechanisms may mediate the benefits of IDS. Additionally, IDS can serve as an ostensive cue eliciting referential expectations.
Fast periodic visual stimulation (FPVS) is employed to investigate the influence of concurrently presented IDS versus adult-directed speech (ADS) on visual categorization. Stimuli are flickered periodically at a fixed rate of F = 6 Hz, with a picture of the target category displayed at every 6th position. To compare the categorization of social and non-social categories, faces and cars will serve as targets in a between-subjects design. EEG activity at the frequency of stimulus presentation (6 Hz and harmonics) and the categorization frequency (1 Hz and harmonics) will be compared.
Beneficial effects of IDS over ADS on visual processing, as compared within subjects, are expected. Moreover, it is anticipated that a social target category is more easily recognized than a non-social one when accompanied by a human voice.
This study aims to deepen the knowledge about neural correlates of multisensory processing using an innovative EEG method.