title: Temporal frequency modulates reaction time responses to first-order and second-order motion.
abstract: This study investigated the effect of temporal frequency and modulation depth on reaction times for discriminating the direction of first-order (luminance-defined) and second-order (contrast-defined) motion, equated for visibility using equal multiples of direction-discrimination threshold. Results showed that reaction times were heavily influenced by temporal frequency, especially in the case of second-order motion. At 1 Hz, reaction times were faster for first-order compared with second-order motion. As temporal frequency increased, reaction times for first-order motion decreased slightly, but those for second-order motion decreased more rapidly. At 8 Hz, reaction times for second-order motion were, in many cases, faster than those for first-order motion. Reaction times decreased as stimulus modulation depth increased at approximately the same rate for both motion types. The findings demonstrate that behavioral response latencies to first-order and second-order motion are dependent on specific stimulus parameters and may, in some cases, be shorter in response to second-order compared with first-order motion.
authors: School of Psychology, University of Leicester. ch190@le.ac.uk
authors: Claire V
authors: CV
authors: Hutchinson
authors: Tim
authors: T
authors: Ledgeway
mesh_terms: D001288:Attention; D002755:Choice Behavior; D015350:Contrast Sensitivity; D004192:Discrimination, Psychological; D005260:Female; D006801:Humans; D007600:Judgment; D008297:Male; D009039:Motion Perception; D009949:Orientation; D010364:Pattern Recognition, Visual; D011601:Psychophysics; D011930:Reaction Time