Out-of-Phase Rhythmic Sampling of Internal Visual Target and Distractor Object Representations Correlates with Target Discrimination

Recent studies suggest that sustained visual attention operates rhythmically, as if the visual system periodically samples stimuli in the environment. In this study, we find evidence for rhythmic attentional sampling of internal representations of Targets and Distractors up to almost one second after the offset of visual stimulation. Twenty participants performed an anticipatory object-based visual attention task in which they were instructed to determine whether a short-lasting Target object image was blurry or not-blurry. This task was made more challenging by the overlaid presentation of a Distractor object image that might also be blurry, requiring focused attention to the cued object category to perform the task successfully. We recorded EEG during the task and performed a decoding analysis on the stimulus-evoked EEG to measure Target and Distractor information present in the scalp voltage topography over the stimulus epoch. We found that the magnitude of the represented Target and Distractor information oscillates in the theta frequency range (4-8 Hz), consistent with previous characterizations of rhythmic attentional sampling. Moreover, we found a correlation between the Target-Distractor theta band phase difference and task performance. Our findings suggest that: 1. Attention separately samples Target and Distractor representations during the cognitive processes that occur between stimulus presentation and behavioral response; 2. These separately sampled streams of information interfere with one another; and 3. Target discrimination improves when Target and Distractor sampling rhythms are desynchronized.