ABSTRACT
Over the past 15 years the value of changes in cardiac activity as a measure of infant cognitive activity has been established. In the early 1960s newborns were found to show reliable heart rate (HR) change when presented with auditory stimuli (Bartoshuk, 1962, a 1962, b; Bridger, 1961). This HR change was assumed to reflect some type of central nervous system response to the auditory stimulus. The concept of using cardiac activity to reflect mental activity was not new, as HR change had been used to detect adult attention to stimuli much earlier (Davis, Buchwald, & Frankmann, 1955; Dykman, Reese, Galbrecht, & Thomasson, 1959; Lacey, Bateman, & Van Lehn, 1953; Lacey & Lacey, 1958). The interpretation of infant cardiac data has been particularly influenced by the Laceys' hypothesis that the direction of HR change reflects different interactions with the environment (Lacey, 1959; Lacey, Kagan, Lacey, & Moss, 1963). Specifically, they noted that attention to external events evoked cardiac deceleration, whereas tasks requiring motivated inattention or those ignoring the environment produced acceleration. Graham and Clifton (1966) related this idea to Sokolov's concepts of orienting and defensive reactions, and concluded that HR deceleration was the cardiac component of the orienting response while acceleration was probably a defense response. In the decade that followed these formulations many investigators contributed to our knowledge of the infant's response to a variety of stimulus situations as measured by cardiac activity. The reader is referred to other sources for a review of this literature (Campos, in press; Clifton, 1974; Graham & Jackson, 1970; Hutt, Lenard, & Prechtl, 1969; Lewis, 1974).
