Development of visual perception and attention, assessed by backward masking and application in children with epilepsy.

Visual masking assesses visual perception and attention; it occurs when a visual stimulus (mask) interferes with the perception of a stimulus that the participant is trying to identify (target). A backward masking study (target presented before mask) was performed on 662 children without disabilities (338 females), aged between 6 and 17 years, in order to evaluate if performance varies with age. In the masking procedure 10 letters were presented through a tachistoscope as target stimuli.