Effect of adaptation direction on the motion VEP and perceived speed of drifting gratings

• Published in: Vision research (Oxford) Vol. 44; no. 20; pp. 2381 - 2392
• Main Authors: Müller, Rolf, Göpfert, Edith, Leineweber, Marcus, Greenlee, Mark W
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2004; Elsevier Science
• Subjects: Adaptation, Physiological; Adult; Biological and medical sciences; Evoked Potentials, Visual - physiology; Female; Fundamental and applied biological sciences. Psychology; Humans; Iso- and counter-directional adaptation; Male; Models, Psychological; Motion Perception - physiology; Motion VEP; Pattern Recognition, Visual; Perceived speed; Perception; Photic Stimulation - methods; Psychology. Psychoanalysis. Psychiatry; Psychology. Psychophysiology; Psychophysics; Speed channels; Stationary adaptation; Vision; Stationary adaptation; Iso- and counter-directional adaptation; Motion VEP; Perceived speed; Speed channels; Human; Stimulus movement; Electrophysiology; Visual evoked potential; Experimental study; Velocity; Spatial frequency; Visual stimulus; Vision; Perception; Stimulus direction
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/j.visres.2004.05.005

The N200 amplitude of the motion-onset VEP evoked by a parafoveal grating of variable contrast (0.5–64%), constant speed (2°/s), direction (horizontally rightward), and spatial frequency (2 cpd) was studied before and after adaptation to a stationary or drifting grating (1, 2, or 4°/s rightward or leftward). These results are compared to those for the pattern-appearance VEP. Psychophysical measurements were made simultaneously of the perceived speed. While iso-directional (rightward) adaptation leads to a mean amplitude reduction of 39%, the decrease after counter-directional adaptation has a size of 20%. The post-adaptation matches of perceived speed differ in dependence on the iso-directional adapting speed and decrease on average to 98%, 85%, and 69% of the pre-adapt perceived speed after 1, 2, and 4°/s adapting speeds, respectively. The perceived speed is moderately reduced (83% of the pre-adapt value) after counter-directional adaptation nearly independently of the adapting speed. A model of velocity processing is presented, which enables us to predict the trends of the experimental motion VEP and perceived speed data.