title: A refractory period for the heart rate response in infant visual attention.
abstract: A refractory period for the heart rate (HR) response of 14-, 20-, and 26-week-old infants to second stimulus onset and primary stimulus offset during termination of visual attention was investigated. A stimulus that elicited a significant HR deceleration was presented. Following the return of HR to prestimulus level, a second stimulus occurred or the first stimulus ended at time delays of 0, 3, 6, and 9 s. If the second stimulus occurred at 0 or 3 s after HR returned to its prestimulus level, the HR response was smaller than the initial HR orienting response (OR). A usual HR OR resulted by waiting 6-9 s after the return of HR to prestimulus level. A significant offset response occurred only for the 6-sec delay. Active inhibition of vagal cardiac activity during attention termination may cause the observed refractory period in the HR response, which appears to last from 3-6 s following sustained attention.
authors.affiliation: University of South Carolina, Columbia.
authors.forename: B J
authors.initials: BJ
authors.lastname: Casey
authors.forename: J E
authors.initials: JE
authors.lastname: Richards
mesh_terms: D000367:Age Factors; D001143:Arousal; D001288:Attention; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D007223:Infant; D008297:Male; D010364:Pattern Recognition, Visual; D002666:Psychology, Child; D012016:Reference Values; D014796:Visual Perception