Electrophysiological evidence for the understanding of maternal speech by 9-month-old infants

Abstract

Early word learning in infants relies on statistical, prosodic, and social cues that support speech segmentation and the attachment of meaning to words. It is debated whether such early word knowledge represents mere associations between sound patterns and visual object features, or reflects referential understanding of words. By measuring an event-related brain potential component known as the N400, we demonstrated that 9-month-old infants can detect the mismatch between an object appearing from behind an occluder and a preceding label with which their mother introduces it. Differential N400 amplitudes have been shown to reflect semantic priming in adults, and its absence in infants has been interpreted as a sign of associative word learning. By setting up a live communicative situation for referring to objects, we demonstrated that a similar priming effect also occurs in young infants. This finding may indicate that word meaning is referential from the outset of word learning and that referential expectation drives, rather than results from, vocabulary acquisition in humans.

Figure 1

An example of the stimuli in a trial for infants. The word is uttered live by either the mother or an experimenter. ERPs were time-locked to the first video frame revealing the top of the object behind the occluder.

Figure 2

ERPs over left and right regions of interest (marked by black contours on the scalp maps). The scalp maps depict the spatial distribution of the difference between word-incongruous and word-congruous objects in the given time windows for adults and infants.