title: Covert visual search within and beyond the effective oculomotor range.
abstract: Covert spatial attention is tightly coupled to the eye-movement system, but the precise nature of this coupling remains contentious. Recent research has argued that covert attention and overt eye-movements many share a common biological limit, such that covert exogenous orienting of attention is limited to stimuli that fall within the range of possible eye movements (the effective oculomotor range: EOMR). However, this conclusion is based on a single experimental paradigm: The Posner cueing task. Here, we examine the extent to which covert spatial attention is limited to the EOMR in visual search. Exogenous attention was assessed using a feature search task and endogenous attention assessed using a conjunction search task. The tasks were performed monocularly with the dominant eye in the frontal position or abducted by 40°. In the abducted position stimuli in the temporal hemispace could be seen, but could not become the goal of a saccadic eye-movement (i.e. they were beyond the EOMR). In contrast, stimuli in the nasal hemifield remained within the EOMR. We observed a significant effect of eye-abduction on feature search, such that search was slower when targets appeared beyond the EOMR. In contrast, eye-abduction had no effect on search times during conjunction search. Set size did not interact with target location or eye-position. It is concluded that optimal covert orienting of exogenous attention in visual search is restricted to locations within the effective oculomotor range.
authors: Department of Psychology, Durham University, Queens Campus, Stockton-on-Tees TS17 6BH, UK. Electronic address: daniel.smith2@durham.ac.uk.
authors: Daniel T
authors: DT
authors: Smith
authors: Department of Psychology, Durham University, Queens Campus, Stockton-on-Tees TS17 6BH, UK.
authors: Keira
authors: K
authors: Ball
authors: Department of Psychology, Durham University, Queens Campus, Stockton-on-Tees TS17 6BH, UK.
authors: Amanda
authors: A
authors: Ellison
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D055815:Young Adult
keywords: Attention; Covert visual search; Endogenous; Exogenous; Eye movement; Oculomotor