Of dogs and men: Recognising one’s own dog engages the same neural processes as recognising personally familiar faces

Recognizing a familiar stimulus is essential to our everyday life. Recent studies revealed details of the nature of the neural dynamics of familiarity representations for human faces. Still, we know relatively little on how different familiar and non-familiar stimulus processing is for non-human face stimuli. Here we report the results of an EEG study, examining the neural dynamics of personally familiar human and dog faces. Participants viewed highly variable images of personally familiar and unfamiliar faces as well as of their own dogs and breed-matched unfamiliar ones. Multivariate pattern analyses were used to examine the time course of differential processing of familiar and unfamiliar human and dog face stimuli. Time-resolved classification revealed that familiarity is decodable from the EEG data from 90 ms onwards, similarly for human and non-human faces. The temporal dynamics were very similar for these categories. Familiarity information, starting at 140-160 ms, generalised across face categories and this generalisation was maintained in a very long time-window. In addition, temporal generalisation analysis showed that familiarity representations have an early, category-specific (90-140 ms) as well as a later, category-independent (>180 ms) processing stage. Our results extend previous human face familiarity evidence to another non-human face category and suggest that familiarity is a general, stimulus-invariant step during recognition memory processing.