M K Reid | PubMed Health

PubMed1984

Effects of methylphenidate (Ritalin) on information processing in hyperactive children.

The effect of methylphenidate on information-processing efficiency was studied in 12 hyperactive, nonretarded children. Performance on six efficiency tasks (Posner Letter Matching, Reaction Time, Memory Search, Category Verification, Item Identification, and Word-Span) and a general measure of on-task behavior were compared for children receiving methylphenidate or a placebo. The median drug dosage was .38 mg/kg, and it was ingested 1 1/2 hours prior to testing. Children blind to the drug-placebo condition were tested on 4 days. In general, methylphenidate-related improvements in attention to on-task behaviors were found. An overall analysis of processing speed suggested that methylphenidate improved efficiency. Methylphenidate significantly decreased reaction times to simple and complex stimulus arrays; differences due to the drug remained even when on-task attentive behaviors were statistically removed. Significantly fewer identification errors occurred on the Posner task in the methylphenidate condition. Results indicated that methylphenidate improved general attentional behaviors and positively influenced processes that define perceptual efficiency.

Adolescent↗

PubMed1983

Impulsivity and strategy transfer: metamemory as mediator.

Acquisition, maintenance, and generalization of organizational strategies were studied as a function of impulsivity-reflectivity and metamemory. In Experiment 1, 64 second- and third-grade children, identified as impulsive or reflective, participated in strategy training and transfer sessions; 25 children in a control condition received the same tasks without strategy training. Strategy and metamemory scores were significantly higher for reflective than impulsive children. Metamemory predicted strategic behavior when cognitive tempo was removed. In Experiment 2, 80 children were given an expanded metamemory battery designed to assess verbalized knowledge of memory processes. Children in the experimental condition were trained to use an organizational strategy and later tested for its maintenance and transfer. Strategy scores were higher for the reflective children during transfer but not training, suggesting a relationship between cognitive tempo and the ability to use strategies in new contexts. Reflective children were again found to have higher metamemory scores. The correlation between metamemory and strategy use with cognitive tempo partialed out was significant, whereas the tempo-strategy use correlation was nonsignificant when metamemory was removed. Strategy maintenance and generalization in impulsive and reflective children appear mediated by metamemorial processes.

Child↗