A SELECTIVE HISTORY OF THE STUDY OF VISUAL-MOTION AFTEREFFECTS

The visual motion aftereffect (MAE) was initially described after obse rvation of movements in the natural environment, like those seen in ri vers and waterfalls: stationary objects appeared to move briefly in th e opposite direction. In the second half of the nineteenth century the MAE was displaced into the laboratory for experimental enquiry with t he aid of Plateau's spiral. Such was the interest in the phenomenon th at a major review of empirical and theoretical research was written in 1911. In the latter half of the present century novel stimuli (like d rifting gratings, isoluminance patterns, spatial and luminance ramps, random-dot kinematograms, and first-order and second-order motions), i ntroduced to study space and motion perception generally, have been ap plied to examine MAEs. Developing theories of cortical visual processi ng have drawn upon MAEs to provide a link between pschophysics and phy siology; this has been most pronounced in the context of monocular and binocular channels in the visual system, the combination of colour an d contour information, and in the cortical sites most associated with motion processing. The relatively unchanging characteristic of the stu dy of MAEs has been the mode of measurement: duration continues to be used as an index of its strength, although measures of threshold eleva tion and nulling with computer-generated motions are becoming more pre valent. The MAE is a part of the armoury of motion phenomena employed to uncover the mysteries of vision. Over the last 150 years it has pro ved itself immensely adaptable to the shifts of fashion in visual scie nce, and it is likely to continue in this vein.