Visual and auditory coding confusability in students with and without learning disabilities

The nature of visual and auditory coding processes in students with learning disabilities (SLDs) and student controls (SCs) was examined with a letter-matching task on four types of successively presented letter pairs: identical (A,A), visually confusable (P,R), auditorily confusable (F,S), and neither visually nor auditorily confusable (N,T). Two delay intervals (0 and 2 seconds) were used between the presentation of the first and second letters. Analysis of decision latencies on the nonidentical letter pair trials revealed that with initial exposure to the task, the SLDs responded more slowly than SCs, but their general confusability patterns (visual and auditory) were similar. With additional practice, overall decision latencies were comparable for the two groups, while confusability differences emerged: SCs showed maximal visual confusability at a 0-second delay and maximal auditory confusability at a 2-second delay, while SLDs did not. Evidently, SLDs make less extensive use of visual and auditory coding processes compared to SCs.