Article

Simultaneous motion contrast across space: Involvement of second-order motion?

Information Science Research Laboratory, NTT Basic Research Laboratories, 3-1 Morinosato-Wakamiya, Atsugi-shi, Kanagawa 243-01, Japan; Department of Psychology, Faculty of Letters, University of Tokyo, Tokyo, Japan
Vision Research (impact factor: 2.41). 02/1997; DOI:10.1016/S0042-6989(96)00112-5 pp.199-214

ABSTRACT A static or counterphase (target) grating surrounded by drifting (inducer) gratings is perceived to move in the direction opposite that of the inducers. We compared the relative magnitudes of these simultaneous motion contrast generated by both first-order and second-order stimuli. The first-order stimuli were sinusoidal luminance-modulations of a uniform field, and the second-order stimuli were sinusoidal contrast-modulations of a random-dot field. When the target was a static grating, the second-order stimuli induced little motion contrast, while the first-order stimuli of the same effective contrast produced clear motion contrast. When the target was a counterphase grating, both first- and second-order stimuli produced clear motion contrast. These results are discussed in relation to the involvement of second-order motion pathways in the relative-motion processing, and the two types of motion aftereffects obtained with static and dynamic test stimuli.

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Keywords

clear motion contrast
 
counterphase
 
counterphase grating
 
drifting
 
dynamic test stimuli
 
first-order
 
first-order stimuli
 
motion aftereffects
 
motion contrast
 
random-dot field
 
relative magnitudes
 
relative-motion processing
 
second-order motion pathways
 
second-order stimuli
 
second-order stimuli induced
 
simultaneous motion contrast
 
static
 
static grating
 
two types
 
uniform field