Respiratory sinus arrhythmia predicts heart rate and visual responses during visual attention in 14 and 20 week old infants.

The prediction oCcardiac attentional responses by respiratory sinus arrhythmia was tested in inCants at 14 and at 20 weeks oCage. Heart rate, heart rate variability, and respiratory sinus arrhythmia were measured in a 5-min baseline period. Respiration and heart rate responses were recorded during the habituation oCinfant visual attention. The level oCrespiratory sinus arrhythmia in the baseline was significantly correlated with the cardiac deceleration, especially in the 20-weekold inCants. The relationship between cardiac and respiratory responses during attention was stronger in the 20-week-olds, paralleling the increase in respiratory sinus arrhythmia at this age. Visual fixation durations were also significantly correlated with measures oCheart rate variability Cromthe baseline. These results imply that cardiac variability not only predicts the level oCcardiac attentional responsivity, but may be useCulin the indexing oCindividual differences in the responsivity oCmore general attentional systems. DESCRIPTORS: Heart rate, Respiratory sinus arrhythmia, Visual attention, InCants. Respiratory sinus arrhythmia may be related to individual differencesin heart rate responses during attention in infants. Several studies with newborn infants (e.g.,Porges, 1974;Porges,Arnold, & Forbes, 1973;Porges, Stamps, & Walter, 1974;Vranekovic, Hock, Isaac, & Cordero, 1974;Williams, Schacter, & Tobin, 1967) have shown that "mature" heart rate responses to psychological stimulation (e.g., heart rate deceleration) occur more often and with greater strength in infants with greater variability in heart rate. Heart rate variability occurring at the same frequency as respiration, respiratory sinus arrhythmia, is largely produced by vagal efferent influences on the heart (Anrep, Pascual, & Rossler, 1935;Katona & Jih, 1975;Porges,McCabe, & Yongue, 1982;Yongue et aI., 1982).It is often assumed that phasic changes in heart rate during attention are of vagalorigin (Coles,Pellegrini,& Wilson, 1982; Graham, 1973; Graham & Clifton, 1966;Lacey & Lacey, 1977;Porges, 1976;Obrist, Webb, Sutterer, This research was conducted in partial fulfillment of the Ph.D. requirements in the Department of Psychology, University of California, Los Angeles. Appreciation is given to David Shapiro for his generous support of this research. Address requests for reprints to: John E. Richards, Department of Psychology, University of South Carolina, Columbia, SC 29208. & Howard, 1970). If it is true that the vagus is critically involved in heart rate attention responses, then it may be possible, by measuring the heart rate variability attributable to respiratory sinus arrhythmia, to measure individual differences in the capacity of the heart to respond with changes in rate during attention, by measuring the level of vagal tone. Respiratory sinus arrhythmia may also be an index of other attentional processes which are related to the cholinergic activity of the nervous system (Porges, 1976). It is not necessarily the case that respiratory sinus arrhythmia in heart rate indexes attentional responsivity because it is measuring vagal tone. It also measures the extent to which respiration influences heart rate during resting. It therefore may measure the potential influence of respiration responses on heart rate during attention. Studies of physiological changes during attention with children and adults have shown a link between both tonic and phasic heart rate and respiration changes. Tasks involving increased attention demands often are accompanied by sustained decreases in respiration frequency and amplitude which are coincident with heart rate deceleration and heart rate variability decreases (Coles, 1972; Cheung & Porges, 1977; Porges & Humphrey, 1977; Porges & Raskin, 1969; Walter & Porges, 1976). Other studies have demonstrated