title: The neural time course of evaluating self-initiated joint attention bids.
abstract: BACKGROUND
  During interactions with other people, we constantly evaluate the significance of our social partner's gaze shifts in order to coordinate our behaviour with their perspective. In this study, we used event-related potentials (ERPs) to investigate the neural time course of evaluating gaze shifts that signal the success of self-initiated joint attention bids.
  
  
  METHODS
  Nineteen participants were allocated to a "social" condition, in which they played a cooperative game with an anthropomorphic virtual character whom they believed was controlled by a human partner in a nearby laboratory. Participants were required to initiate joint attention towards a target. In response, the virtual partner shifted his gaze congruently towards the target-thus achieving joint attention--or incongruently towards a different location. Another 19 participants completed the same task in a non-social "control" condition, in which arrows, believed to be controlled by a computer program, pointed at a location that was either congruent or incongruent with the participant's target fixation.
  
  
  RESULTS
  In the social condition, ERPs to the virtual partner's incongruent gaze shifts evoked significantly larger P350 and P500 peaks compared to congruent gaze shifts. This P350 and P500 morphology was absent in both the congruent and incongruent control conditions.
  
  
  CONCLUSIONS
  These findings are consistent with previous claims that gaze shifts differing in their social significance modulate central-parietal ERPs 350 ms following the onset of the gaze shift. Our control data highlights the social specificity of the observed P350 effect, ruling out explanations pertaining to attention modulation or error detection.
authors.affiliation: Department of Cognitive Science, Macquarie University, Sydney, Australia; ARC Centre of Excellence in Cognition and its Disorders, Sydney, Australia; Perception in Action Research Centre, Sydney, Australia. Electronic address: nathan.caruana@mq.edu.au.
authors.forename: Nathan
authors.initials: N
authors.lastname: Caruana
authors.affiliation: Department of Cognitive Science, Macquarie University, Sydney, Australia; ARC Centre of Excellence in Cognition and its Disorders, Sydney, Australia; Department of Psychology, Macquarie University, Sydney, Australia. Electronic address: peter.delissa@mq.edu.au.
authors.forename: Peter
authors.initials: P
authors.lastname: de Lissa
authors.affiliation: Department of Cognitive Science, Macquarie University, Sydney, Australia; ARC Centre of Excellence in Cognition and its Disorders, Sydney, Australia. Electronic address: genevieve.mcarthur@mq.edu.au.
authors.forename: Genevieve
authors.initials: G
authors.lastname: McArthur
mesh_terms: D000328:Adult; D001288:Attention / Q000502:physiology*; D002540:Cerebral Cortex / Q000502:physiology*; D003299:Cooperative Behavior; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D055815:Young Adult
keywords: ERPs; Eye gaze; Eye tracking; Joint attention; Social interaction; Virtual reality