Working memory and inhibitory control in early childhood: Contributions from physiology, temperament, and language.
This study examined the cognitive skills of working memory and inhibitory control (WMIC) in relation to physiological functioning, temperament, and language in early childhood. WMIC skills were assessed in twenty-five 4 1/2-year-old children using the day--night Stroop-like task and the yes--no task; each task required the child to remember two rules and to inhibit a dominant response. Electroencephalogram (EEG) and heart period (HP) were recorded during baseline and WMIC tasks. An increase in 6- to 9-Hz EEG power from baseline to task was found for the medial frontal region. In addition, a decrease in HP (i.e., an increase in heart rate) was found from baseline to task. Associations were found between performance on the WMIC tasks and scales of the Children's Behavioral Questionnaire (CBQ) related to the effortful control of behavior. The Peabody Picture Vocabulary Test-III (PPVT-III) distinguished between high and low WMIC performance. Results of a discriminant function analysis indicated that physiology, temperament, and language were able to correctly predict 90% of WMIC performance.