Abstract
Good and poor readers differ on a variety of visual processes related to visual attention and rate of visual processing. Poor readers show increased visual attentional dwell time, evidence of left visual field “minineglect,” differences on measures related to visual magnocellular processes (higher dot motion coherence threshold, constrast sensitivity for low spatial and high temporal frequency stimuli), and lower accuracy on measures of visual masking. The current study examined reader group differences in performance on one form of backward masking that is related to visual attention - four dot masking. 132 children in Grade 1, half at risk of reading disability, and half typically developing readers matched on age and gender, were administered a four-dot masking task in which target location (left and right visual fields), eccentricity (central, peripheral), and mask duration (48, 96, and 192 ms) were varied. Poor readers consistently scored lower than poor readers. Poorer performance was found at the 192 ms duration condition, showing that the expected four-dot masking effect was obtained, and stronger masking was found for peripheral targets compared with central targets. Although no location effect was found in the overall sample, a subgroup of poor readers, scoring one or more SD below the average on a standardized reading measure, showed anomalous performance for targets in the left visual field, but not for targets in the right visual field. Results are discussed in relation to visual attentional development in good and poor readers.
Supported by the Social Sciences and Humanties Resarch Council of Canada