Lexical access in college students with learning disabilities: an electrophysiological and performance-based investigation.
The purpose of this study was to compare the semantic processing abilities of college students with learning disabilities (LD) to those of their peers without learning disabilities (NLD) who were matched for age, gender, and intelligence. Participants were compared on results from the Test of Adolescent/Adult Word Finding (TAWF) and from event-related potential (N400) sampling to the processing of semantically incongruous sentences. The LD and NLD groups did not significantly differ in accuracy on the TAWF; however, students with LD demonstrated a significantly greater number of delayed responses. The LD group's N400 responses were significantly delayed at the Pz electrode site. Effect size indicators also revealed somewhat reduced amplitudes at Fz and Cz locations. The significant delays of the students with LD on standardized testing and on N400 suggest an inefficiency in the semantic processing of these individuals, in both automatic and attention-based aspects of lexical access.
Rubin
Scott S
SS
Department of Speech Pathology and Audiology, University of South Alabama, Mobile 36688-0002, USA. srubin@usouthal.edu
Johnson
Clinton M
CM
D000293:Adolescent; D000328:Adult; D001288:Attention; D003071:Cognition; D004569:Electroencephalography; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D007859:Learning Disabilities / Q000503:physiopathology*; D008297:Male; D008606:Mental Processes; D012660:Semantics; D013647:Task Performance and Analysis