Dataset for "Beyond motion extrapolation: vestibular contribution to head-rotation-induced flash-lag effects"

This dataset comprises of the data presented in the publication "Beyond motion extrapolation: vestibular contribution to head-rotation-induced flash-lag effects" (He et al., 2022) and the codes for data analyses.For the study, we designed a custom VR equipment with a head-mounted display and a motion sensor fastened to a helmet, which could collect real-time data of the observer's movement and deliver it to the computer instantly, thus helping us manipulate the visual stimuli to present according to the profile of the observer's self-motion.In Experiment 1, we measured and compared the head-rotation-induced flash-lag effects elicited in participants while they executed yaw head or body rotations. There was 3 coniditions in terms of the types of rotation, where participants actively rotated their head while keeping other body parts still, rotated their trunk while keeping the head still (with the help of a swivel chair and a custom head fixing device), or passively had their whole body rotated by the experimenter while seated in the swivel chair, respctively. A slender, vertical white bar was presented at the center of the visual field using the VR goggle, keeping stationary as the reference stimulus. At a random moment in the middle of participants' rotation every time, another identical bar flashed above the reference bar for ~16.7 ms, with possible horizontal offsets of 0, ±1, ±3, or ±5 pixels relative to the reference bar (0 meant the two bars were vertically aligned; "±" meant leftward or rightward shift). Participants had to report whether they saw the flash bar appeared to the left or right of the reference bar. A control condiition was also included where participants did not rotate at all and sat still. Later, percentages of participants' choice were fitted against the offsets of the flash bar with a logistic function to estimate participants' perceptual mislocalization of the flash bar, i.e. the head-rotation-induced flash-lag effect.In Experiment 2, we introduced retinal motion on the basis of Experiment 1. In two conditions, participants respectively rotated their head only or rotated their trunk only, like in Experiment 1. At the beginning of each trial, the reference bar started moving horizontally from the edge of display in the opposite direction to the participants' head rotation (or the head rotation direction relative to the trunk) at the speed of their real-time rotating speed, which was designed to simulate an stationary object in the outside world while the observer moves. When it crossed the vertical midline of the visual field, another bar flashed above it in the same manner as in Experiment 1. Participants still had to report whether they saw the flash bar appeared to the left or right of the reference bar. In the third condition, participants did not rotate and sat still, in order to induce a traditional flash-lag effect for comparison.In Experiment 3, we trained participants to adapt to a new association between visual motion direction and self-motion direction, in order to test whether the head-rotation-induced flash-lag effect could be induced based on this newly trained visual-vestibular association of motion directions. Pariticipants were presented with a full-field, horizontal sinusoidal grating stimulus while rotating their head, and the grating kept drifting contingently on their head rotation: the grating always drifted downwards when participants rotated their head leftwards and vice versa, and its speed varied real-time to match participants' head rotation. Every a few times of rotations done, a test would cut in for the vertical flash-lag effect, similarly as in Experiment 1 except that the whole display seemed rotated by 90 degrees: a slender, horizontal white reference bar was presented stationary at the center of display, and another identical bar flashed on the left or right of the reference bar with a possible vertical offset.For details of the dataset, please see readme.txt in the root directory after unzipping. For details of the study, please refer to:He, X., Bai, J., Jiang, Y., Zhang, T., & Bao, M. (2022). Beyond motion extrapolation: vestibular contribution to head-rotation-induced flash-lag effects. Psychological Research, 1-16. https://doi.org/10.1007/S00426-021-01638-8.