Is covert visual search biologically constrained by the effective oculomotor range?

We typically move attention around the environment with overt eye-movements. However, it is also possible to orient attention covertly, such that the 'spotlight' of attention is moved independently of the locus of gaze. While there is enduring debate about the relationship between the mechanisms controlling covert and overt attention, one influential view is that shifts of covert attention are achieved by planning (but not executing) and overt eye movement. We have previously shown that placing stimuli at locations beyond the effective oculomotor range (EOMR) interfered with covert, exogenous orienting to peripheral cues but not covert endogenous orienting driven by symbolic cues (e.g. Smith et al., 2012; Smith & Casteau 2019). Here, we examined whether the association between exogenous attention and the EOMR observed in cueing tasks generalised to visual search tasks. We first measured the EOMR for each participant, then presented search arrays that were either within or beyond their EOMR. Feature search was significantly slower when stimuli were presented beyond the range of eye-movements whereas conjunction search was unaffected. In a second study we parametrically varied the location of the array to better establish how well changes in search performance mapped onto the range of eye-movements. The results confirmed that preattentive search was restricted to the locations within the range of eye-movement. We conclude that optimal covert, exogenous orienting of attention depends on the oculomotor system, consistent with an Oculomotor Readiness hypothesis of Exogenous Orienting. [ABSTRACT FROM AUTHOR]