||Position displacement, not velocity, is the cue to motion detections of second-order stimuli.
Explored the detection of 1st-order (luminance-based) and various 2nd-order (texture- and stereo-based) motion using a procedure to dissociate the target's velocity and position provided by K. Nakayama and C. W. Tyler (1981). In Exp 1, 6 observers viewed annular gratings oscillating in rotational motion at various rates. For 1st-order motion, these motion detection thresholds decreased with increasing temporal frequency and were determined by a minimum velocity. Motion detection thresholds for 2nd-order motion remained roughly constant across temporal frequency. In Exp 2, luminance-based gratings of different contrasts were tested to show that the velocity-dependence was not an artifact of pattern visibility. In Exps 3 and 4, results similar to Exp 1 were obtained with a central presentation of a linear grating, instead of an annular grating, and with a motion discrimination rather than motion detection task. It is concluded that, within the ranges tested here, 2nd-order motion is more readily detected with a mechanism which tracks the change of position of features over time. (PsycINFO Database Record (c) 2007 APA, all rights reserved)