The sequential nature of action ensures that an individual can anticipate the conclusion of an observed action via the use of semantic rules. The semantic processing of language and action has been linked to the N400 component of the event-related potential (ERP). The authors developed an ERP paradigm in which infants and adults observed simple sequences of actions. In one condition the conclusion of the sequence was anticipated, whereas in the other condition the conclusion was not anticipated. Adults and infants at 9 months and 7 months were assessed via the same neural mechanisms-the N400 component and analysis of the theta frequency. Results indicated that adults and infants at 9 months produced N400-like responses when anticipating action conclusions. The infants at 7 months displayed no N400 component. Analysis of the theta frequency provided support for the relation between the N400 and semantic processing. This study suggests that infants at 9 months anticipate goals and use similar cognitive mechanisms to adults in this task. In addition, this result suggests that language processing may derive from understanding action in early development.
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 using event-related brain potentials, we demonstrate that 9-month-old infants detect the mismatch between an object appearing from behind an occluder and a preceding label with which their mother introduces it. The N400 effect has 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 demonstrate that a similar priming effect also occurs in young infants. This finding may indicate that word meaning is referential from the outset, and it drives, rather than results from, vocabulary acquisition in humans.
A precondition for successful communication between people is the detection of signals indicating the intention to communicate, such as eye contact or calling a person's name. In adults, establishing communication by eye contact or calling a person's name results in overlapping activity in right prefrontal cortex, suggesting that, regardless of modality, the intention to communicate is detected by the same brain region. We measured prefrontal cortex responses in 5-month-olds using near-infrared spectroscopy (NIRS) to examine the neural basis of detecting communicative signals across modalities in early development. Infants watched human faces that either signaled eye contact or directed their gaze away from the infant, and they also listened to voices that addressed them with their own name or another name. The results revealed that infants recruit adjacent but non-overlapping regions in the left dorsal prefrontal cortex when they process eye contact and own name. Moreover, infants that responded sensitively to eye contact in the one prefrontal region were also more likely to respond sensitively to their own name in the adjacent prefrontal region as revealed in a correlation analysis, suggesting that responding to communicative signals in these two regions might be functionally related. These NIRS results suggest that infants selectively process and attend to communicative signals directed at them. However, unlike adults, infants do not seem to recruit a common prefrontal region when processing communicative signals of different modalities. The implications of these findings for our understanding of infants’ developing communicative abilities are discussed.
The importance of eye gaze as a means of communication is indisputable. However, there is debate about whether there is a dedicated neural module, which functions as an eye gaze detector and when infants are able to use eye gaze cues in a referential way. The application of neuroscience methodologies to developmental psychology has provided new insights into early social cognitive development. This review integrates findings on the development of eye gaze processing with research on the neural mechanisms underlying infant and adult social cognition. This research shows how a cognitive neuroscience approach can improve our understanding of social development and autism spectrum disorder.
We examined infants' oscillatory brain activity during a live interaction with an adult who showed them novel objects. Activation in the alpha frequency range was assessed. Nine-month-old infants responded with desynchronization of alpha-band activity when looking at an object together with an adult during a social interaction involving eye contact. When infant and experimenter only looked at the object without engaging in eye contact, no such effect was observed. Results are interpreted in terms of activation of a generic semantic knowledge system induced by eye contact during a social interaction.
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