Attentional facilitation of detection of flicker on moving objects.

We investigated the influence of attention and motion on the sensitivity of flicker detection for a target among distractors. Experiment 1 showed that when the target and distractors were moving, detection performance plummeted compared to when they were not moving, suggesting that the most sensitive detectors were local, temporal frequency-tuned receptive fields. With the stimuli in motion, a qualitatively different strategy was required and this led to much reduced performance. Cueing, which specified the target location with 100% validity, had no effect for targets that had little or no motion, suggesting that the flicker was sufficiently salient in this case to attract attention to the target without requiring any search. For targets with medium to high speeds, however, cueing provided a strong increase in sensitivity over uncued performance. This suggests a significant advantage for localizing and tracking the target and so sampling the luminance changes from only one trajectory. Experiment 2 showed that effect of attention was to increase the efficiency and duration of signal integration for the moving target. Overall, the results show that flicker sensitivity for a moving target relies on a much less efficient process than detection of static flicker, and that this less efficient process is facilitated when attention can select the relevant trajectory and ignore the others.