Poster E8, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Distractor suppression varies with expectation
MaryAnn Noonan1, Yannik Bauer2, Alex Von Lautz3, Christopher Summerfield1, Mark Stokes1; 1Department of Experimental Psychology, University of Oxford, Oxford, UK, 2International Max Planck Research School, University of Tübingen, Germany, 3Bernstein Center for Computational Neuroscience, Berlin, Germany.
We have recently suggested distractor inhibition emerges when the predictive information can be inferred directly from past experience. Specifically, we found that distractor suppression is only effective when distractors repeat across a block of trials and not when distractor location is cued on a trial-wise basis (Noonan et al., 2016, JON). We now explore whether predictions of environmental stability are embedded in higher order expectations. In a speeded target discrimination task subjects are implicitly cued to the location of the target or distractor via manipulations in the underlying predictability of the two stimuli. Repetitions of either target or distractor location could therefore be either expected or unexpected. Behaviourally, reaction times were reduced when either stimuli was more spatially predictable. Critically this decrease in RT across spatial predictability is driven by expected stimulus repetition. We recorded EEG while subjects performed this task. Focusing on single repetitions, collapsed across all spatial predictions, we show enhanced P1 amplitudes controlateral to targets on target repetition trials and a suppressed P1 contralateral to distractors on distractor repetition trials. Further we report that this P1 suppression is driven by expected distractor repetitions. Notably the complementary effect is not seen in the expected target repetition trials. A follow-up study explores the temporal properties of distractor expectation. By varying inter-stimulus-intervals on a trial-wise basis we begin to disentangle repetition suppression from expectation.
Topic Area: ATTENTION: Spatial