Electrophysiological decoding captures the temporal trajectory of face categorization in infants

The adult human brain rapidly distinguishes between faces at around 170 ms after stimulus onset. During early brain development, however, face discrimination is thought to require almost twice as much processing time. To re-examine this long-standing assumption, we presented human and nonhuman primate faces to five to thirteen-month-old infants in an event-related electroencephalography experiment. Using time-resolved decoding based on logistic regression we detected above-chance discrimination of human faces from nonhuman faces in a time window already starting at around 200 ms, originating from occipito-temporal electrodes. There was no evidence, however, for above-chance discrimination of individual human or individual nonhuman faces. These results indicate that rapid face categorization emerges already in preverbal infants.