Abstract
Previous studies have shown that self-motion (heading) perception is biased toward display center (center bias) and affected by recently-seen stimuli (serial dependence). Here, we examined effects of head and body orientations on center bias and serial dependence in heading perception. The display (80°×80°) simulated observer translation (3m/s) through a 3D random-dot cloud (depth range: 0.57–2.0m) consisting of 200 dots. On each 500-ms trial, heading direction was randomly chosen from −24° (left) to +24° (right) with respect to display center (0°) in steps of 4°. Participants judged direction of heading with a mouse-controlled probe under three conditions: (1) head and body orientations were aligned with display center, (2) head was rotated 10° away from body midline that was aligned with display center, and (3) head and body midline were aligned and rotated 10° from display center. To evaluate center bias, we performed a linear regression between perceived and actual heading. To evaluate serial dependence, we combined a first derivative of Gaussian function with a sinusoidal function to fit residual heading error (difference between perceived and predicted heading with center bias in the current trial) as a function of relative heading offset (difference in actual heading of previous trial and current trial). We found: (1) an overall bias in heading judgments toward head and body orientation direction; when head and body orientations were not aligned with display center, (2) a decrease in center bias, (3) an increase in the range of central attractive serial dependence, and (4) an increase in the amplitude of peripheral repulsive serial dependence in heading judgments. Our findings show both egocentric and world-centric centers contribute to center bias in heading perception. When world-centric center is not aligned with egocentric center, people increase their reliance on recently-seen heading directions for heading judgments.
Acknowledgement: the National Natural Science Foundation of China (31741061), Shanghai Science and Technology Committee (15DZ2270400, 17ZR1420100), and NYU-ECNU Joint Research Institute