Experimental evidence for a transient system deficit in specific reading disability.

This paper summarizes the experimental evidence for a transient system deficit in specific reading disability. Differences have been found between controlled readers and specifically disabled readers in measurements of visible persistence, pattern contrast sensitivity and temporal or flicker contrast sensitivity. This transient system deficit was found in approximately 75% of the specifically reading disabled subjects tested. A further series of experiments failed to demonstrate differences in sustained system function between the two groups. Evidence is also presented which suggests that the visual system deficit precedes the reading disability. Possible mechanisms of the impact of a transient system deficit on reading are discussed.