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Jennifer Lechak, Erika Wells, Andrew Leber; Greater sensitivity to visual motion predicts a greater capacity to ignore it. Journal of Vision 2012;12(9):1341. doi: 10.1167/12.9.1341.
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Efficient visual search performance sometimes demands exquisite sensitivity to very subtle changes in our environment, while at other times demands that we ignore highly salient information. How are these seemingly divergent processes linked? One clue comes from a recent study showing that individuals with greater evoked fMRI activity from passively viewed motion exhibited greater behavioral distraction in a separate task when the motion was to be ignored (Lechak & Leber, under revision). This suggests that greater sensitivity to visual motion makes one less able to resist processing it. To directly test this possibility in the current study, we examined the relationship between an individual’s psychophysical motion sensitivity threshold and a measure of behavioral distraction. To obtain motion thresholds, observers completed a two-interval forced choice task in which coherent motion was to be discriminated from random dot motion. Dots in the coherent interval were varied in coherence from 4% to 50%, and an accuracy threshold of 75% was estimated for each observer. To obtain the distraction measure, observers searched 10-item displays for a target square among circles and reported whether the target had a gap in the top or bottom. On 50% of the trials a moving distractor singleton appeared 50 ms before target onset. RT on these trials was compared to RT on distractor-absent trials to yield a behavioral distraction index. Results showed a positive correlation between coherence thresholds and the distraction index, r = 0.52, p = 0.023. That is, observers who were less sensitive to visual motion were less able to ignore salient distracting motion. These results are inconsistent with the proposal that greater sensitivity to motion makes one less able to resist it. Instead, an individual’s ability to enhance processing of task-relevant stimuli and suppress processing of irrelevant stimuli could be subserved by a common mechanism.
Meeting abstract presented at VSS 2012
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