A model of repetitive microsaccades , coupled with pre - microsaccadic changes in vision , is sufficient to account for both attentional capture and inhibition of return in Posner cueing

When a cue is presented at a location (Fig. 1a), orienting efficacy towards that location is improved relative to other locations (“attentional capture”), but only briefly; a mere few hundred milliseconds later, orienting incurs large costs. These costs have been classically termed “inhibition of return” (IOR), alluding to voluntary, cognitive strategies avoiding perseverance at one location. However, despite this popular hypothesis, the origins of both attentional capture and IOR remain to be elusive. To understand Posner cueing mechanisms, we were motivated by two observations. First, tiny fixational microsaccades occur in a machine-like manner during cueing, with their temporal and spatial patterns likely being dictated by low-level, subcortical oculomotor reflexes. Second, prior to each microsaccade, there are significant changes in visual processing that take place (also see Chen, Ignashchenkova, and Hafed, VSS, 2015), which probably help establish perceptual stability in the face of eye movements. We developed a model testing a simple hypothesis: that the repetitive occurrence of tiny microsaccades, coupled with pre-microsaccadic changes in vision, is entirely sufficient to account for both attentional capture and IOR in Posner cueing. The first component of the model (Fig. 1b) accounts for the highly systematic temporal structure of microsaccades during cueing, and it is based on our earlier model. Briefly, we simulated a repetitive microsaccade process using simple rise-to-threshold; a microsaccadic accumulator rose linearly with constant slope towards a threshold: