ABSTRACT
In the next three chapters, we discuss research that has led to the majority of the psychophysiology concepts outlined in chapter 2. Many of the concepts presented in chapter 2 are rooted in autonomic activity, especially cardiovascular. The research described examines the subtle interactions between physiology and behavior. An example is the decrease in heart rate that occurs during the orienting response, a drop that leads to improved intake of the stimulus to which the individual is attending. The increase in heart rate in response to threatening stimuli defines the defensive response that lessens sensitivity to aversive stimuli. Then there are the subtleties of directional fractionation in which, depending on the stimulus situation, heart rate and skin conductance may increase together or diverge. For example, in visual attention heart rate has been observed to decrease whereas skin conductance increased. However, in a cognitive task (thinking) both heart rate and skin conductance increase in magnitude. The cardiac-somatic concept began as an explanatory device in which changes in heart activity were seen as facilitating the performance of a response, for instance, the association between heart rate deceleration and the inhibition of muscle activity not related to the task. The concept has been expanded to include a great deal of information on coping and noncoping situations and the influence of these on cardiovascular reactivity and elevated blood pressure. Other concepts presented in chapter 2 were autonomic balance and the law of initial values, both based on autonomic activity.
