Recognition memory and cardiac vagal tone in 6-month-old infants

Individual differences in visual recognition memory and cardiac vagal tone were assessed in 14 6-month-old infants. A multi-dimensional problem was presented with the paired-comparison technique to assess recognition memory. Cardiac vagal tone was evaluated by quantifying the amplitude of respiratory sinus arrhythmia. Individual differences in spontaneous baseline cardiac vagal tone were correlated with two measures of visual recognition memory. Infants characterized by high cardiac vagal tone looked for shorter periods at the standard (i.e., familiar) stimulus during familiarization and looked for longer periods at the novel stimulus during the test trials. In response to the visual stimulus during the familiarization and test trials, heart rate decelerated only for the infants who performed well on the visual recognition memory task (i.e., those who looked longer at the novel stimulus than the familiar stimulus).