Abstract

The motion aftereffect is a robust illusion of visual
motion resulting from exposure to a moving pattern.
There is a widely accepted explanation of it in terms of
changes in the response of cortical direction-selective
neurons. Research has distinguished several variants of
the effect. Converging recent evidence from different
experimental techniques (psychophysics, single-unit
recording, brain imaging, transcranial magnetic stimulation,
visual evoked potentials and magnetoencephalography)
reveals that adaptation is not confined to one or even two cortical areas, but occurs at multiple levels of processing involved in visual motion analysis. A tentative motion-processing framework is described, based on motion aftereffect research. Recent ideas on the function of adaptation see it as a form of gain control that maximises the efficiency of information transmission at multiple levels of the visual pathway.