CARDIAC VAGAL TONE AND SUSTAINED ATTENTION IN SCHOOL-AGE-CHILDREN

Three hypotheses tested relationships between cardiac responses mediat ed via the vagus and sustained attention in a population of normal sch ool-age children. These hypotheses addressed the theoretical relations hips among resting cardiac vagal tone (using the Forges estimate of re spiratory sinus arrhythmia, (V) over cap, performance measures of sust ained attention, and cardiac reactivity during sustained attention. Th irty-two fourth and fifth grade children performed a continuous perfor mance task while their electrocardiograms were monitored. Children wit h higher resting levels of (V) over cap performed better on the first 3-min block of the continuous performance task. Additionally, levels o f (V) over cap were significantly reduced across the blocks of the 9-m in task for ah children. No relationships were found between resting l evels of (V) over cap and change in either (V) over cap or heart perio d during task performance. These findings support two of the three hyp otheses proposed by Forges regarding individual differences in cardiac vagal tone and sustained attention.