[Mechanisms of early light and dark adaptation]

A possible role of transient and sustained mechanisms of vision in early light and dark adaptation was studied using the adaptive fields with different rates of luminance changes. The curve forms of early light and dark adaptation and time integration at different rates of switching on and off the adaptive field were studied as well as the changes of contrast sensitivity related to rates of background luminance changes. The data obtained confirm participation of transient and sustained mechanisms of vision in early light and dark adaptation. The contribution of each mechanism depends on the rate and direction of the luminance changes.