1. Evidence of Inhibitory Processing During Visual Search
Asenath Arauza, Dustin M. Elliott, Jordan Salwei, Linda Langley & Laura Thomas
North Dakota State University – Department of Psychology L T
On Probe
Introduction
Search Task
Results
Results
Visual Search Reaction Times (ms)
Participants responded faster on target-present trials than on target absent trials, F(1,30) = , p < .001.
Participants responded faster to trials with a set size of 6 than a set size of 12, F(1,30) = , p < .001
There was a significant interaction between target presence and set size, F(1,30) = , p < The set size effect was larger for target absent trials.
Probe Detection
On probe RTs were slower than off probe RTs, consistent with IOR effects, F(1, 30) = 10.10, p = .003.
Probe RTs following target absent trials were slower than probe RTs following target present trials, F(1, 30) = 84.36, p <
Probe condition did not interact with target presence, F(1, 30) = .03, p = .86, or search task set size, F(1, 30) = 1.85, p = .18. The three-way interaction was also not significant, F(1, 30) = 1.84, p = .19.
Inhibition of return (IOR) is a cognitive mechanism that is thought to improve visual search efficiency by biasing attention to new locations.
During visual search, inhibitory tags are placed at searched locations, which discourages repeated inspection of the same stimuli.
Evidence for this tagging system can be demonstrated with a probe detection task (Klein, 1988) in which, after a search task, a probe is presented either at a distractor location (on-probe) or at a previously unoccupied space (off-probe). Klein found that longer probe-detection reaction times (RTs) were observed at on-probe locations, presumably due to search-related inhibition remaining at that location.
The current study is part of a sequence of studies exploring age differences in inhibition during search. We sought to replicate Klein’s (1988) tagging effect in young adults using search arrays developed by Thomas and Lleras (2009).
We predicted that evidence of IOR would show as slower RTs to on-probes compared off-probes. L T
Off Probe L T
Target Present
200 ms L
On Probe L
Target Absent L
Off Probe
Until target present/absent response
Until probe detection response
Probe Detection
Search Times
Conclusions
Replicating Klein (1988) and Thomas and Lleras (2009), we found evidence for inhibition during search. Participants were slower to detect a probe when it was presented at a possibly searched location than when it was presented at a location without a search item, suggesting inhibitory tags had facilitated successful search.
We now are in the process of collecting data to determine whether older adults (a) are as successful as young adults at the search task, and (b) use inhibition to guide search. We predict that older adults will find the search task more difficult, being more greatly impacted by target absence and increasing set size. We also predict that impaired IOR will account for some age-related impairments in search.
Method
Participants: 31 younger adults (18-27 years; M=19 years; 16M/15F).
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. Following a yes or no response, half of the time a probe was presented.
Probe Task: 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.
Send correspondence to Asenath Arauza at