Infrequent faces bias social attention differently in manual and oculomotor measures

Although attention is thought to be spontaneously biased by social cues like faces and eyes, recent data have demonstrated that when extraneous content, context, and task factors are controlled, attentional biasing is abolished in manual responses while still occurring sparingly in oculomotor measures. Here, we investigated how social attentional biasing was affected by face novelty by measuring responses to frequently presented (i.e., those with lower novelty) and infrequently presented (i.e., those with higher novelty) face identities. Using a dot-probe task, participants viewed either the same face and house identity that was frequently presented on half of the trials or sixteen different face and house identities that were infrequently presented on the other half of the trials. A response target occurred with equal probability at the previous location of the eyes or mouth of the face or the top or bottom of the house. Experiment 1 measured manual responses to the target while participants maintained central fixation. Experiment 2 additionally measured participants' natural oculomotor behaviour when their eye movements were not restricted. Across both experiments, no evidence of social attentional biasing was found in manual data. However, in Experiment 2, there was a reliable oculomotor bias towards the eyes of infrequently presented upright faces. Together, these findings suggest that face novelty does not facilitate manual measures of social attention, but it appears to promote spontaneous oculomotor biasing towards the eyes of infrequently presented novel faces.