Action-speech and gesture-speech integration in younger and older adults: An event-related potential study

In daily communication, speech is enriched with co-speech gestures, providing a visual context for the linguistic message. It has been shown that older adults are less sensitive to incongruencies between context (e.g., a sentence) and target (e.g., a final sentence word). This is evidenced by a smaller and delayed N400 (in)congruency effect that reflects the difference between the N400 component in response to congruent versus incongruent targets. The present study investigated whether the effect of age on the N400 effect in sentence-final word integration would also arise for verb-gesture/action integration. Assuming that gestures have a tight connection to language these would provide a higher contextual constraint for the action phrase than the literal actions (i.e., an action performed on an object can be understood in isolation, without the action phrase). EEG was recorded from a sample of younger and older participants, while they watched audio-visual stimuli of a human actor performing an action or pantomime gesture while hearing a congruent or incongruent action phrase. Results showed that the N400 (in)congruency effect was less widespread in the older than the younger adults. It seemed that older adults, but not younger adults were less sensitive to the gestural than the action (object) information when processing an action phrase.