A SELECTIVE HISTORY OF THE STUDY OF VISUAL-MOTION AFTEREFFECTS

The visual motion aftereffect (MAE) was initially described after observation of movements in the natural environment, like those seen in rivers and waterfalls: stationary objects appeared to move briefly in the opposite direction. In the second half of the nineteenth century the MAE was displaced into the laboratory for experimental enquiry with the aid of Plateau's spiral. Such was the interest in the phenomenon that a major review of empirical and theoretical research was written in 1911. In the latter half of the present century novel stimuli (like drifting gratings, isoluminance patterns, spatial and luminance ramps, random-dot kinematograms, and first-order and second-order motions), introduced to study space and motion perception generally, have been applied to examine MAEs. Developing theories of cortical visual processing have drawn upon MAEs to provide a link between pschophysics and physiology; this has been most pronounced in the context of monocular and binocular channels in the visual system, the combination of colour and contour information, and in the cortical sites most associated with motion processing. The relatively unchanging characteristic of the study of MAEs has been the mode of measurement: duration continues to be used as an index of its strength, although measures of threshold elevation and nulling with computer-generated motions are becoming more prevalent. 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 proved itself immensely adaptable to the shifts of fashion in visual science, and it is likely to continue in this vein.