Visual evoked potentials: relation to adult speechreading and cognitive function.

This study investigated the putative relationship between visual evoked potentials (VEPs) and specific aspects of speechreading. The nature and constraints of the relationship between VEPs and cognitive functioning was also examined. The original finding of Shepherd, DeLavergne, Frueh, and Clobridge (1977) that visual-neural speed (VN 130) predicts speechreading skill was not replicated. However, the picture is rather complex in that we find significant correlations for some context-free word discrimination and sign-alphabet testing conditions. These correlations occur only for the VN 130/P 200 peak-to-peak amplitude measure, not for neural speed. Nevertheless, visual-neural speed (VN 130 and P 200) was relevant to certain aspects of long-term memory access (i.e., letter matching, Posner & Mitchell, 1967) and to complex short-term memory function (i.e., reading span, Baddeley, Logie, Nimmo-Smith, & Brereton, 1985).