Rotating stripes provide a simultaneous display of sustained and transient channels

A slowly rotating striped pattern provides an instantaneous display of the temporal response characteristics of the visual system. The effect seen is that of a central column of clearly resolved stripes. The distribution of contrast across the width of the band displays the temporal frequency response; the spatial phase of the resolved stripes shows the temporal phase response of the mechanisms involved; and the orientation of the band indicates the transport delay. This band consists of two distinct regions, which suggests that there are at least two independent channels involved. At low temporal frequencies, a linear channel capable of carrying colour information mediates the appearance; at higher temporal frequencies, a nonlinear, achromatic channel predominates. The chromatic response to the pattern suggests that there is some interaction between channels. Computer simulation of a sustained and a transient channel produces an output similar to that perceived, thereby reinforcing the notion that this simple device enables one to display simultaneously the properties of the sustained and transient channels.