The effect of non-communicative eye movements on joint attention.

Eye movements provide important signals for joint attention. However, those eye movements that indicate bids for joint attention often occur among non-communicative eye movements. This study investigated the influence of these non-communicative eye movements on subsequent joint attention responsivity. Participants played an interactive game with an avatar which required both players to search for a visual target on a screen. The player who discovered the target used their eyes to initiate joint attention. We compared participants’ saccadic reaction times (SRTs) to the avatar’s joint attention bids when they were preceded by non-communicative eye movements that predicted the location of the target (Predictive Search), did not predict the location of the target (Random Search), and when there were no non-communicative eye gaze movements prior to joint attention (No Search). We also included a control condition in which participants completed the same task, but responded to a dynamic arrow stimulus instead of the avatar’s eye movements. For both eye and arrow conditions, participants had slower SRTs in Random Search trials than No Search and Predictive Search trials. However, these effects were smaller for eyes than for arrows. These data suggest that joint attention responsivity for eyes is relatively stable to the presence and predictability of spatial information conveyed by non-communicative gaze. Contrastingly, random sequences of dynamic arrows had a much more disruptive impact on subsequent responsivity compared with predictive arrow sequences. This may reflect specialised social mechanisms and expertise for selectively responding to communicative eye gaze cues during dynamic interactions, which is likely facilitated by the integration of ostensive eye contact cue

The influence of intentional stance on the neural encoding of joint attention

Theoretical thesis.Bibliography: pages 54-63.Introduction -- Methods -- Results -- Discussion.Adopting an intentional stance towards a social partner is a crucial component of evaluating the success of joint attention, where social interlocuters must represent the mind and perspectives of others. Recent work has established that centroparietal P250 and P350 ERPs are sensitive to whether the gaze shifts of others signal the achievement or avoidance of joint attention, and that this modulation depends on the adoption of an intentional stance (Caruana & McArthur, 2019). The current study attempted to replicate these effects, determining their reliability across testing contexts, and examining the influence of the aesthetic anthropomorphism of the stimuli used. Participants initiated gaze-cued joint attention bids with an on-screen virtual partner, which shifted its eye gaze congruently to respond to joint attention bids on 50% of trials and responded incongruently to avoid joint attention on the remaining trials. Participants were told that in one block their partner was controlled by a human, and in another by a computer program. The aesthetic anthropomorphism of the faces was manipulated between-subjects so that one group interacted with an animated human face (n=21), and the other interacted with a humanoid robot face (n=19) . Larger P250 mean amplitudes were measured in response to congruent gaze shifts compared to incongruent, and the opposite pattern was observed for P350 responses. However, these ERPs were not reliably modulated by the adoption of an explicit intentional stance across both stimulus groups. We found tentative evidence to suggest that this unreliability may be explained by individual differences in anthropomorphism tendencies.1 online resource (67 pages) colour illustration