Abstract
Cross-modal conflict arises when information from different sensory modalities are incompatible with each other. Such conflict may influence the processing of stimuli in the task-relevant modality (and call for cognitive control to resolve this conflict). Here we investigate how reward modulates cross-modal conflict control during object categorization by manipulating reward (reward vs. no-reward) and stimuli type (visual-only vs. audio-visual congruent vs. audio-visual incongruent). In visual-only condition, only images of objects were presented. In audio-visual conditions, images of objects and sounds commonly associated with specific objects were presented simultaneously, with the image and the sound either congruent (associated with the same object) or incongruent (associated with different objects). Participants were instructed to categorize the images (animate/inanimate) and ignore the sounds while their brain activities were recorded by EEG. At the beginning of each block, a cue was presented indicating reward availability of that block. In a reward block, correct responses with RT faster than the baseline RT (mean RT of the practice trials) were rewarded, whereas in no-reward block no reward was delivered irrespective of performance. Behaviorally, reward facilitated performance in a stimuli type-dependent manner: in no-reward conditions, RTs were shorter for congruent trials than for incongruent trials; this difference was absent in reward conditions. Neurally, we found that the fronto-central N2 (240-320 ms) was larger in the incongruent condition than in the congruent condition, but only when there was no reward for performance. Time-frequency analysis revealed a conflict-related modulation of the non-phase-locked theta power over the fronto-central sites, but again, only for no-reward conditions. Taken together, our results demonstrate that reward modulates cross-modal conflict resolution and the conflict-related N2 and theta-band neural oscillations.
Meeting abstract presented at VSS 2017