The effects of contrast, stimulus duration, and spatial frequency on visible persistence in normal and specifically disabled readers

Conducted 2 experiments with 21 normal and 21 specific-reading-disabled readers (mean age 14 yrs 3 mo). The Neale Analysis of Reading Ability revealed a mean reading lag of 4 yrs 8 mo. Ss were presented with 2 successive stimuli and asked to report whether the interstimulus interval between the 2 gratings was a blank or a grating. Exp I showed that the function relating visible persistence to spatial frequency was significantly flatter in disabled than in normal readers. Disabled readers had longer durations of visible persistence at low spatial frequencies and relatively shorter durations at high spatial frequencies. Exp II used a cycling measure to show that this effect was exaggerated at low contrast levels and was greatest with stimulus durations that approximated fixation durations in reading. In disabled readers, reducing contrast increased duration of visible persistence at low spatial frequencies but decreased visible persistence duration at high spatial frequencies. (60 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).