Center-surround effects on perceived speed.
We investigated whether center-surround interactions affect perceived speed in a manner similar to their effects on direction discrimination thresholds [e.g. Tadin, D., Lappin, J. S., Gilroy, L. A., & Blake, R. (2003). Perceptual consequences of center-surround antagonism in visual motion processing. Nature, 424, 312-315]. Observers were asked to match the speed of a test stimulus (a grating, with fixed contrast and no surround) to that of a reference stimulus of variable contrast and with a variably sized surround, moving at one of two possible velocities (1 and 12cps). At 1-cps, both lowering contrast and increasing surround-size resulted in a decrease in perceived speed, except for very low contrast stimuli, where a larger surround resulted in an increase in perceived speed. Although the effect of surround-size was comparable in the two velocity conditions, the effect of contrast was different at 12-cps. That is, in the 12cps condition, a decrease in perceived speed was observed only for the lowest contrast used. Our results suggest that, at least for the lower velocity used, center-surround interactions affect perceived speed in a manner analogous to their effect on direction discrimination.
van der Smagt
Maarten J
MJ
Utrecht University, Helmholtz Institute, Experimental Psychology Division, Heidelberglaan 2, 3584 CS Utrecht, Netherlands. M.J.vanderSmagt@uu.nl
Verstraten
Frans A J
FA
Paffen
Chris L E
CL
D015350:Contrast Sensitivity / Q000502:physiology; D004192:Discrimination, Psychological / Q000502:physiology*; D006801:Humans; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D012684:Sensory Thresholds / Q000502:physiology; D012858:Size Perception / Q000502:physiology