Daniel Lougen¹, Jay Pratt¹; ¹University of Toronto

Inhibition of Return (IOR) is a phenomenon where responses to targets appearing at previously attended locations are slower after a certain temporal interval, enhancing visual search efficiency by discouraging attention from revisiting examined areas. This study investigates whether the spatial frequency of cues and targets modulates IOR by selectively engaging either the magnocellular (sensitive to low spatial frequencies; LSFs) or the parvocellular (sensitive to high spatial frequencies; HSFs) visual pathways. We conducted a typical visual cueing task (two horizontally aligned cue/target locations with placeholders ) with participants completing one of four cueing conditions: LSF cues, HSF cues, LSF targets, or HSF targets. These cues and targets were circles filled with black and white bars at 3 cpd (LSF) or 12 cpd (HSF). The control cues and targets were a white outline with a solid black circle. The inter-stimulus interval (ISI) between cue and target ranged from 100 ms to 1400 ms in order to examine the time course of IOR in each condition. In the spatial frequency cue conditions, we found that LSF and HSF cues generated typical – and equivalent – IOR effects and time courses. In the spatial frequency target conditions, we observed a surprising result; the lack of IOR with both spatial frequencies across all ISIs . Across all conditions, we additionally found the expected decrease in RTs synonymous with longer ISIs, indicating that participants attended to both cues and targets. Overall, the evidence from this study is indicative of a stronger effect centered around relationship between the physical features of cues and targets rather than what pathway is primed to process the stimuli.