Polarity specific adaptation to motion in the human visual system.

Three experiments investigated polarity specific adaptation to movement. Experiment 1 tested for temporal polarity specific adaptation, using counterphase sawtooth gratings as adapting and test stimuli. Each counterphase grating contained oppositely moving sawtooth components, and was thus balanced for direction, but both components of the adapting grating created only one polarity of luminance change over time, whereas the components of the test grating presented different signs. After adaptation, only the test component containing the unadapted temporal change was visible. A second experiment, using an analogous procedure, found evidence for spatial polarity specific adaptation. Experimental results can be explained by motion detectors which preserve information about spatial and temporal polarity. A third experiment found that spatial and temporal polarity specific adaptation differ in their dependence on temporal frequency.