### Hardware * Dell Optiplex GX280 computer (one for displaying stimuli, one for running the eyetracker) * CRT monitor * 21 inches * 1024 x 768 resolution * 85 Hz refresh rate * 60 cm view distance * Desktop-mounted chin and forehead rest * SR Research Eyelink1000 tracker (250 Hz sampling rate, monocular tracking with left eye) ### Software * MATLAB 20011b * Psychophysics Toolbox version 3 * SR Research Eyelink II/CL v 2.32 eye-tracking software running from DOS ### Stimuli and Procedure The stimuli used were arrays of 8 Gabors presented on a gray background. These Gabors had a diameter of 62 pixels/2.6˚, with a spatial frequency of ~ .94 cycles per degree and a randomly chosen orientation. They were placed in fixed positions in a ring around a central fixation dot (0.17˚/4 pixel) at a radius of 77 pixels/3.30˚, measured from the center of the cross to the center of the Gabor. Each trial began with the fixation dot presented alone on one side of the display for 500ms, followed by the onset of the Gabor array. The array immediately started moving toward the center of the display for a distance of 7.37˚ of visual angle (172 pixels) at a constant velocity of 14.57˚ per second (4 pixels per refresh). When the center of the Gabor array reached the center of the screen, the target Gabor rotated 30 degrees in one refresh. The Gabor array then did one of two things: * In the “flexion” condition, this rotation occurred as array instantly changed direction, turning either 90˚ (upwards) or 270˚ (downwards) and traveling for another 6.34˚/148 pixels * In the “control” condition, the array continued on straight for 7.37˚/172 pixels When it reached the end of its path, the array offset and reappeared 100 ms later in the center of the display under the words “Click the one that rotated.” The target orientation change occurred equally often (5 times) at each of the 8 Gabor positions, crossed with two directions of travel and three post-rotation paths for a total of 240 randomly ordered trials. ![Schematic of experiment 3][1] Dotted lines indicate the path of motion the array took after target rotation in the flexion (blue) and control (orange) conditions. There were two possible directions of travel: left-to-right (pictured) and right-to-left. [1]: https://mfr.osf.io/export?url=https://osf.io/tnzp4/?action=download%26mode=render%26direct%26public_file=False&initialWidth=684&childId=mfrIframe&format=1200x1200.jpeg