Luminance processing in object substitution masking.

We probed how processing of luminance increments and decrements interacts with attention dependent substitution masking. Results showed that a target was identified better when surrounded by an opposite polarity mask as compared to the same polarity mask. Opposite polarity mask decreased an effect of distracters, indicating influence on the time of directing attention to a target. The opposite polarity mask decreased masking when delayed for longer than 100 ms. Stimuli with the same polarity but different contrast showed increased masking with high contrast mask. Luminance processing, particularly polarity processing, probably enables faster formation of distinct object representation, interacting with attentional selection processes in object substitution masking.