Abstract
There is considerable overlap in the brain areas that control overt shifts of gaze and covert shifts of attention. In visual perception, these two functions are naturally linked because information sampled at covertly attended locations often informs where to look next. We ask whether the brain’s oculomotor system also participates in attentional focusing when there is no incentive for overt shifts of gaze: when attention is voluntarily directed to one out of multiple visual items held internally within the spatial layout of visual working memory. Paradoxically, we showcase this participation through gaze behaviour itself. We demonstrate that selecting an item from visual working memory leads to an increased propensity of micro saccades in the direction of the memorised location of that item – even when there is nothing to look at and even when location memory is never asked about. Building on this key observation, we further show that this retrospective ‘gaze bias’ is specific to cases where the probed memory item is not already in the focus of attention, and predicts the performance benefit associated with such focusing (experiment 2); that externally-induced gaze shifts of similar magnitude are insufficient to place memory items into the focus of attention (experiment 3); and that this gaze bias generalises across the selection of different visual features (orientation and colour; experiment 4). We conclude that the oculo-motor system also plays a key role in attentional focusing within the internal space of visual working memory, and that such ‘internal focusing’ can be studied through the eyes.
Acknowledgement: This research was funded by a Marie Sklodowska-Curie Fellowship from the European Commission (ACCESS2WM) to F.v.E., and a Wellcome Trust Senior Investigator Award (104571/Z/14/Z) to A.C.N.