Abstract
The natural environment's predictable structure facilitates various cognitive tasks, from planning motor behaviors to efficiently allocating attention. We set out to study the cognitive and neural impact of unexpected items that subjects are attempting to ignore. To do this, we adapted Eriksen's flanker task to incorporate "standard" and "oddball" distractors. Arrays of five chevrons were briefly presented (50 ms), and subjects reported the orientation of the central target chevron, attempting to ignore the four chevrons that flanked the target. We manipulated the orientation of the distractors, creating standard (90% of trials) and oddball (10%) orientations. Congruent and incongruent configurations, and left- and right-pointing central targets were equiprobable. While subjects performed the task, we recorded scalp EEG signals. EEG measures included the visual mismatch negativity (vMMN) elicited by oddball flanker directions, and alpha-band (8-12 Hz) oscillations preceding stimulus onset. Subjects also completed the Adult Temperament Questionnaire, a measure of sensory, emotional, and motor reactivity and control. Behaviorally, oddball flankers substantially enhanced the flanker congruency effect: subjects responded fastest and most accurately on trials with oddball flankers that were congruent with the central target, and slowest and least accurately on trials with oddball flankers that were incongruent. Oddball flankers also elicited a vMMN. Importantly, individual differences in vMMN magnitude were predicted by two factors of temperament: orienting sensitivity and attentional control. Subjects may be using the predictability of the flankers to facilitate intentional ignoring, a strategy that breaks down when confronted with oddballs. Unexpected events are obligatorily processed, even when they occur among distractors. Such events leak through subjects' intentional ignoring, influencing neural responses and behavioral performance.
Meeting abstract presented at VSS 2014