Effects of event probability and sequence on children with attention-deficit/hyperactivity, reading, and math disorder.
BACKGROUND
We investigated the impact of stimulus probability and sequence on performance and event-related potentials of 310 children classified into 12 combinations of attention-deficit/hyperactivity disorder (Not-attention-deficit/hyperactivity disorder, Inattentive and Combined subtypes) with presence/absence of reading disorder and math disorder.


METHODS
Subjects pressed buttons to displays of the letters O and X, which were presented with probabilities of either .17/.83 or .50/.50. Greater response selection was required in the .17/.83 condition.


RESULTS
Stimulus probability had comparable effects on all diagnostic groups. The extent of mismatch between a stimulus and preceding events elicited less systematic increases in errors, P3b latency, and P3b amplitude among both attention-deficit/hyperactivity disorder subtypes than controls. Mismatch with preceding trials more greatly reduced math disorder and reading disorder + math disorder children's speed in the Rare task and accuracy in both conditions. Math disorder and reading disorder + math disorder subjects also registered less the effects of alternations of the infrequent O on N2 amplitude and on P3b latency.


CONCLUSIONS
Math disorder and reading disorder + math disorder youngsters' lower sensitivity to sequence irregularity in their event-related potentials along with greater disruption of performance suggest working memory deficits that adversely affected response selection. Comorbidity of attention-deficit/hyperactivity disorder and reading disorder did not affect the results.
Klorman
Rafael
R
Meliora Hall, University of Rochester, RC Box 270266, Rochester, NY 14620-0266, USA.
Thatcher
Joan E
JE
Shaywitz
Sally E
SE
Fletcher
Jack M
JM
Marchione
Karen E
KE
Holahan
John M
JM
Stuebing
Karla K
KK
Shaywitz
Bennett A
BA
D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000150:complications / Q000503:physiopathology*; D001921:Brain / Q000503:physiopathology; D002648:Child; D004410:Dyslexia / Q000150:complications / Q000503:physiopathology; D005071:Evoked Potentials; D005260:Female; D006801:Humans; D007859:Learning Disabilities / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008433:Mathematics; D008568:Memory; D011930:Reaction Time; D013647:Task Performance and Analysis