Substitution masking affects the visibility of equiluminant coloured stimuli

In object substitution masking (OSM) a target becomes inaccessible to consciousness when a lateral mask stays on the screen after it disappears. Similarity between target and distractors along certain properties, seems to affect this effect. Particularly, the role of inhomogeneous colours between target and distractors in modulating OSM is debated. This study was aimed to evaluate the magnitude of OSM on isoluminant stimuli in both colour and letter identification. Results show high individual variability on target detectability and the same amount of OSM on both color and letter identification tasks, suggesting that it affects feature binding as much as feature detection. A dynamic 4-dot mask: The size of masking on coloured stimuli Mereu, Stefania Dipartimento di Psicologia, Universita di Roma, Roma, Italy Casagrande, Maria Dipartimento di Psicologia, "Sapienza" Universita` , Roma, Italy The visibility of a target is reduced when a lateral mask remains on the display after the target disappears. This effect seems to be independent of the image-level characteristics of the stimulus. This study would verify the efficacy of a 4-dot masking, in which an apparent motion illusion is added on coloured stimuli otherwise difficult to mask. Both localization and colour identification tasks are assessed, in both masked and unmasked conditions. Results show the efficacy of this dynamic masking on coloured stimuli, and seem to confirm the independence of 4-dot masking from the visual characteristics of stimuli.