ISSN 1671-3710
CN 11-4766/R

Advances in Psychological Science ›› 2019, Vol. 27 ›› Issue (suppl.): 19-19.

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The flash-lag effect during head rotation: Beyond the motion extrapolation hypothesis

Xin Hea,b, Jianying Baia,c,d, Yi Jiangb,e,f, Tao Zhangb,e, Min Baoa,b,e   

  1. aCAS Key Laboratory of Behavioral Science, Institute of Psychology, Chinese Academy of Sciences, Beijing, People's Republic of China;
    bDepartment of Psychology, University of Chinese Academy of Sciences, Beijing, People's Republic of China;
    cXinjiang Astronomical Observatory, Chinese Academy of Sciences, Urumqi, People's Republic of China;
    dUniversity of Chinese Academy of Sciences, Beijing, People's Republic of China;
    eState Key Laboratory of Brain and Cognitive Science, Beijing, People's Republic of China;
    fCAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai, People's Republic of China
  • Online:2019-08-26 Published:2022-03-21

Abstract: PURPOSE: The present study examined the roles of vestibular and visual motion signals in the head-rotation-induced flash-lag effect (FLE), and tested the validity of the motion extrapolation hypothesis for this type of FLE.
METHODS: Participants kept rotating their heads in the horizontal plane during the experiments. Stimuli were presented on an HMD. A 3-Space Sensor, attached on top of the HMD, acquired the head motion data in real-time. In Experiment 1, subjects maintained a central fixation, while a vertical reference bar either remained stationary on the center of the screen or moved at the same speed as the observer's head rotation from one side of the screen to the other but in the opposite direction of the head rotation. The latter condition simulated a circumstance that the reference bar remained static in the environment with the retinal motion signal completely resulting from the head rotation. Horizontal FLEs were measured and compared between the two conditions. In Experiment 2, head rotation was associated with vertical drift of a full-field grating. Both horizontal and vertical FLEs were measured.
RESULTS: We found reliable horizontal FLE in Experiment 1 whether the reference bar was stationary or moving on the screen. Moreover, the FLEs in the two conditions were in the same direction, showing comparable magnitudes. In Experiment 2, there was a weak but significant vertical FLE, though its magnitude was greatly smaller than the horizontal FLE.
CONCLUSIONS: The motion extrapolation hypothesis predicts no horizontal FLE in Experiment 1 given that the reference bar is considered to be static in the environment. Besides, the hypothesis cannot explain the vertical FLE in Experiment 2. Taken together, the present findings do not support the motion extrapolation account for the FLE induced by head movement. Instead, the findings are discussed in relation to the modulation of vestibular signals on visual motion signal processing.

Key words: flash-lag effect, motion extrapolation, vestibular, head movement