Date of Award

Summer 2019

Document Type

Open Access Dissertation



First Advisor

Jessica Green


Inhibition of return (IOR) refers to the finding that responses to previously attended locations are slower than those to previously unattended locations. Despite over 30 years of research on IOR, there is still no consensus in the field regarding what the underlying mechanism of this effect is. Although IOR is traditionally studied within spatial cueing paradigms, this effect is thought to reflect a mechanism that facilitates efficient visual search. The following studies explored the hypothesis that multiple processes contribute to the IOR effect in visual search and examined whether these are the same processes that result in IOR in cueing tasks. Both behavioral and electrophysiological measures were used to investigate the response patterns and processes underlying IOR in visual search, and subsequently examine those patterns and processes in cueing-like situations. Chapter 2 explored the spatial distribution of IOR within visual search using the N2pc and P1 ERP components. Chapter 3 investigated how IOR is influenced by attentional manipulations to the visual search task. Chapter 4 used the N2pc, P1, and Pd ERP components to examine the influence of priming and distractor suppression on IOR in visual search, in an effort to link IOR-related findings from the visual search and cueing literatures. Overall, the results demonstrated that IOR observed in cueing studies does not appear to result from the same underlying processes as IOR observed in visual search. This suggests that not only do multiple processes underlie the slowing of responses we refer to as IOR, but also that studies of IOR using cueing tasks may not be informative for understanding the mechanisms of efficient visual search.