in the Study of Attachment
NATHAN A. FOX
JUDITH A. CARD
“Psychophysiology” is the study of how physiological processes intersect with and influence psychologically relevant behavior. Psychophysiological research includes the measurement of physiological systems as correlates of observed behavioral responses, as well as the manner in which individual differences in the level of a physiological response predispose subjects to certain types of behavior. Developmental psychologists have measured multiple physiological responses and have inferred certain psychological processes from these measurements. This is particularly true of research on the preverbal human infant: Researchers have measured physiology in an attempt to understand the competencies of the young infant, and have inferred the presence or absence of specific affective states on the basis of these physiological responses. These studies are usually based upon certain assumptions about the role of physiological systems in the generation of behavioral responses. Such assumptions are the product of a long history of research in psychophysiology with adults and older children. Before tackling the psychophysiological literature on attachment, we provide a brief overview of the use of psychophysiological methods in psychology.
METHODS IN PSYCHOLOGY
Heart rate (HR) has the longest history as a psychophysiological measure of preverbal infants’ cognitive and affective responses. As a result of the work of Lacey and Lacey (1958), researchers investigated HR responses of infants to a variety of stimuli (e.g., Lewis, 1975; Lewis, Kagan, Campbell, & Kalafat, 1966). Lacey and Lacey reported that adult subjects displayed HR acceleration during periods of cognitive processing (e.g., mental arithmetic) when it was necessary to reject external distractions. Subjects displayed HR deceleration during periods of quiet attention to stimuli presented to them. The Laceys argued that these directional changes in HR facilitate cognitive processing. HR acceleration prevents attention to external events and provides an individual with the opportunity to concentrate on “internal thinking,” whereas HR deceleration allows the individual to focus and attend to external events.
Graham and Clifton (1966) took this model and adapted it to the study of cognitive processing in the human infant. They argued that one can assess an infant’s psychological response to a