Rhythmic alternate prioritization in auditory feature-based attention

Accumulating evidence suggests that attentional resources are distributed in a rhythmically alternating fashion between several simultaneously competing inputs. Most past research on this topic has investigated the visual modality, with some evidence of rhythmic sampling in auditory spatial attention. Here, we tested whether rhythmic sampling also extends to the auditory feature domain. Twenty-five human participants performed a challenging feature-based auditory attention task. On each trial, we presented an auditory cue (high or low tone) followed by a variable delay (250-1000 ms) and a target (high or low tone) at detection threshold, either congruent or incongruent with the cue (50% probability). By analyzing performance as a function of the cue-target interval, we arrived at three main results. First, sensitivity fluctuated significantly at a rate of 8 to 10 Hz for both congruent and incongruent targets, in line with cyclical waxing and waning attention towards the two features. Second, sensitivity in congruent and incongruent trials fluctuated out-of-phase with each other, suggesting an alternating prioritization of the two features. Third, across subjects, larger phase differences between conditions were associated with faster response times, indicating that alternate sampling facilitates task performance. In summary, our results demonstrate attentional sampling in yet another task domain and corroborate the idea of cyclic information processing as a key mechanism underlying information selection in the brain.