Brightness of uniform stabilized fields

Brightness of uniform fields during normal and stabilized viewing was determined as a function of adapting luminance, field size, and luminance gradient of the edges of the adapting field. In one set of experiments, it was found that, over a range of adapting luminances from 6 to 9600 td, a uniformly-illuminated 7.5 deg hemifield appeared about 1 log unit brighter in normal viewing than when it was retinally-stabilized. In the second set of experiments, it was found that the loss of brightness due to stabilized viewing was significantly greater for large fields with raised cosine edges than for small fields with step edges. Both sets of results can be accounted for by a two-stage model of light adaptation previously proposed to account for the fading time of stabilized images.