Poster Session D, Monday, March 25, 8:00 – 10:00 am, Pacific Concourse
Behavioral Rhythms in Saliency-based Figure-ground Segregation
Ying Fan1,2,3,5, Jianrong Jia4,5, Huan Luo1,2,3; 1School of Psychological and Cognitive Sciences, Peking University, 2PKU-IDG/McGovern Institute for Brain Research, Peking University, 3Beijing Key Laboratory of Behavior and Mental Health, Peking University, 4Peking-Tsinghua Center for Life Sciences, Peking University, 5These authors contributed equally to the work
Foreground figures can be effortlessly separated from background based on saliency information. Recent studies have demonstrated that attention samples multiple foreground objects dynamically. However, it remains unknown how figure and background, which are determined by bottom-up saliency information, are processed and coordinated in time. In the present study, participants were first presented with a display consisted of twelve discs, each of which had one of the three colors. Importantly, the number of discs associated with each of the three colors were one, three, and eight respectively. Using this manipulation, the colors related to fewer (1 or 3) and more discs (8) would serve as foreground and background features respectively. Next, after a variable delay (120:20:600 ms), an oriented bar having one of the three colors was presented, and participants were required to judge the orientation of the bar. The mean reaction time (RT) and accuracy across all stimulus-onset asynchronies (SOAs) showed no difference across the three conditions. Intriguingly, the RT time courses associated with the figure and background colors displayed different temporal profiles. Specifically, the behavioral traces for the foreground and background colors fluctuated at theta-band (3-5 Hz) and alpha-band rhythm (8-10 Hz) respectively, and the two foreground colors exhibited an alternation pattern. Moreover, the background-alpha power was related to the foreground-theta phase difference. Our results suggest a time-based figure-ground segregation, such that figures are processed via theta-band, and background is suppressed by alpha-band. The stronger the suppression of the background, the clearer separation between the two figures is.
Topic Area: ATTENTION: Nonspatial