Eye-movement patterns to social and non-social cues in early deaf adults.

Previous research on covert orienting to the periphery suggested that early profound deaf adults were less susceptible to uninformative gaze-cues, though were equally or more affected by non-social arrow-cues. The aim of this work was to investigate whether spontaneous eye movement behaviour helps explain the reduced impact of the social cue in deaf adults. We tracked the gaze of 25 early profound deaf and 25 age-matched hearing observers performing a peripheral discrimination task with uninformative central cues (gaze vs arrow), stimulus-onset asynchrony (250 vs 750 ms), and cue validity (valid vs invalid) as within-subject factors. In both groups, the cue effect on reaction time (RT) was comparable for the two cues, although deaf observers responded significantly slower than hearing controls. While deaf and hearing observers' eye movement pattern looked similar when the cue was presented in isolation, deaf participants made significantly more eye movements than hearing controls once the discrimination target appeared. Notably, further analysis of eye movements in the deaf group revealed that independent of the cue type, cue validity affected saccade landing position, while latency was not modulated by these factors. Saccade landing position was also strongly related to the magnitude of the validity effect on RT, such that the greater the difference in saccade landing position between invalid and valid trials, the greater the difference in manual RT between invalid and valid trials. This work suggests that the contribution of overt selection in central cueing of attention is more prominent in deaf adults and helps determine the manual performance, irrespective of the cue type.