Neural activity associated with attention orienting triggered by implied action cues.

Spatial attention can be directed by the actions of others. We used ERPs method to investigate the neural underpins associated with attention orienting which is induced by implied body action. Participants performed a standard non-predictive cuing task, in which a directional implied action (throwing and running) or non-action (standing) cue was randomly presented and then followed by a target to the left or right of the central cue, despite cue direction. The cue-triggered ERPs results demonstrated that implied action cues, rather than the non-action cue, could shift the observers' spatial attention as demonstrated by the robust anterior directing attention negativity (ADAN) effects in throwing and running cues. Further, earlier N1 (100-170ms) and P2 (170-260ms) waveform differences occurred between implied action and non-action cues over posterior electrodes. The P2 component might reflect implied motion signal perception of implied action cues, and this implied motion perception might play an important role in facilitating the attentional shifts induced by implied action cues. Target-triggered ERPs data (mainly P3a component) indicated that implied action cues (throwing and running) speeded and enhanced the responses to valid targets compared to invalid targets. Furthermore, P3a might imply that implied action orienting may share similar mechanisms of action with voluntary attention, especially at the novel stimuli processing decision-level. These results further support previous behavioral findings that implied body actions direct spatial attention and extend our understanding about the nature of the attentional shifts that are elicited by implied action cues.