Evidence of Inhibitory Processing During Visual Search Dylan L. Rogers, Hannah K. Staska, Dustin M. Elliott, Asenath X. Arauza, Linda K. Langley & Laura Thomas North Dakota State University – Department of Psychology L T On Probe Search Task Introduction Results Results Visual Search Reaction Times (ms) Participants responded faster on target-present trials than on target absent trials, F(1,62) = 367.30, p = .0001. Older adults were slower to make a search response than young adults, particularly on target-absent trials, and when there were more distractors in the array, F(1,62)=12.77, p=.0007. Probe Detection Older adults were slower overall to detect the probe compared to younger adults, F(1,62) = 119.88, Participants were slower to detect the probe following target absent arrays, F(1,62) = 72.40, p = .0001. On-probe RTs were slower than off-probe RTs, consistent with IOR effects, F(1,62) = 16.57, L T Inhibition of return (IOR) increases the efficiency of visual search by reducing the likelihood of re-inspecting previously attended-to items. Through this mechanism, inhibitory tags are assigned to locations occupied by distractor items, thus attention is prompted to search novel locations. Previous research shows that young adults produce an inhibitory tagging effect in both spatial cuing and visual search tasks (Klein, 1988; Thomas & Lleras, 2009). A study on spatial cuing shows that the mechanism persists into older adulthood (Langley, Fuentes, Vivas, & Saville, 2007). The current study examined whether older adults also utilize inhibitory tagging in visual search. The current study is part of a sequence of studies exploring the maintenance of IOR in later adulthood. We predicted that evidence of IOR would be maintained in older adulthood during visual search. Off Probe L T Target Present L On Probe L Target Absent L Off Probe 200 ms Until target present/absent response Until probe detection response Conclusions Probe Detection Replicating Klein (1988) and Thomas and Lleras (2009), we found evidence for inhibition during visual search for young adults. We extended this finding to older adults. Participants were slower to detect a probe when it was presented at a likely searched location than when it was presented at a location without a search item, suggesting inhibitory tags had facilitated efficient detection of the target. Although older adults’ visual search performance was slower than that of young adults, there was no evidence that this search deficit was due to impaired inhibitory tagging. Instead, both young and older adults maintained tags when target was both present and absent. Method Participants: 32 younger adults (18-21 years; M=19 years; 8M/24F); 32 older adults (60-86 years; M=69 8M/24F). Search Task: Participants searched visual arrays of 6 or 12 items for a target (a “T” amongst “L’s”), and indicated whether the “T” was present or not. Probe Task: Following a yes or no response, a probe was presented on half of the trials. Participants pressed a designated key if they detected the probe (a box). On half the probe trials, the probe was presented at a location previously occupied by a distractor (on-probe), and on the other trials it appeared at a previously empty location (off-probe). Participants completed 10 blocks of 32 trials for a total of 320 trials. IOR would be reflected in slower detection of on-probes to off-probes. Send correspondence to Asenath Arauza at asenath.arauza@ndus.edu