Concepts in Psychophysiology
Explanatory concepts enable scientists to categorize and understand large amounts of data. They also suggest hypotheses to be tested and questions to be asked by investigators of various phenomena and, thus, help to guide the researcher. The answers obtained through experimental study may suggest modification or elaboration of existing concepts, or a relationship with other formulations. Within the field of psychophysiology, the most elaborate of the concepts deal with cardiovascular or autonomic activity in one form or another. Concepts concerning brain responses are as numerous, but not as well-developed. In addition, there are formulations regarding electrodermal response and muscle activity. Thus, the field of psychophysiology does not have an all-inclusive conceptual framework within which most of the collected data may be tested, integrated, and interpreted. Instead, there are a number of concepts that have relevance for the interpretation of experimental findings. Some of these concepts, at least in part, contradict one another. Perhaps one day, the various concepts may be reconciled and subsumed within one or a few theoretical frameworks that will account for most of the existing data. This is probably an overly optimistic goal, but one for which scientists in diverse areas, including psychophysiology, constantly strive.
Scientific concepts and theories enable isolated findings and information to be bound together into a meaningful pattern. They provide a basis for the interpretation of past and present information and act as stimulators for future investigations. The very experiments that are suggested by a given scientific concept may be responsible for the modification or elimination of the concept. The development of concepts includes the sharpening of predictive value and modifications to accommodate an increasing number of new facts. The development of these kinds of concepts is one sign of a maturing science. The concepts discussed in this chapter are the law of initial values, autonomic balance, activation, stimulus response specificity, individual response specificity, cardiac-somatic coupling, adaptation, rebound, the orienting response, and defensive responses. In addition, conceptual approaches in the areas of social psychophysiology and event-related brain potentials are considered.
The law of initial values (LIV) states that a particular physiological response to a given stimulus or situation depends on the prestimulus level of the system being measured (e.g., see Wilder, 1957, 1967, 1976). More specifically, the law says that the higher the initial level, the smaller the increase in physiological response to a given stimulus. On the other hand, the higher the level, the larger the decrease produced by stimuli normally capable of producing decreases. How might the LIV predict a change in HR in a given situation? It has been found