Objective: Dyslexia is associated with impairments in the phonological system or with more general auditory dysfunctions. We determined the discrimination of 5 sound contrasts (pitch, duration, intensity, location, and the presence of a gap) in dyslexia with the mismatch negativity (MMN).
Methods: We compared MMNs of 9 adult dyslexic and 11 control subjects with a new 5-deviant paradigm which enables one to assess the discrimination of each of these features in 15 min. Also, a control oddball condition with pitch and duration deviants was included. In the new paradigm, all deviant stimuli are presented in the same stimulus block so that the standard stimuli, of which there are 50%, alternate with the deviant stimuli.
Results: In the 5-deviant paradigm, a diminished pitch-MMN and an enhanced location-MMN were found in dyslexic individuals. Furthermore, pitch and duration MMNs in this and in the oddball paradigms suggested that smaller MMNs are elicited in the new than oddball paradigm in dyslexic subjects.
Conclusions: Pitch discrimination is impaired in dyslexia. However, location discrimination, not addressed previously with MMN, is enhanced. Furthermore, dyslexic subjects are more impaired in detecting changes in sound streams with than without variation.
Significance: In dyslexia research, the new 5-deviant MMN paradigm is feasible and even more sensitive than the traditional oddball paradigm.