ABSTRACT
The relation between brain physiology and behavior is a new domain of inquiry, far from even a preliminary synthesis. Scientists who study temperamental variation in children who are not psychiatric patients are usually limited to measuring peripheral processes that are distant from the central origins of primary interest. Psychologists interested in temperament have a choice of strategy that is influenced partly by how they balance two complementary motives. Interest in the physiology that might contribute to the differences in fearful behavior invited measurement of two important peripheral systems. One important reason for the relative independence of conscious feelings and physiology, as well as independence among different physiological variables, is that each target system is especially responsive to a narrow range of incentives that is related to its unique biological purpose. However, magnitude of heart rate acceleration to a change in posture and selected psychological intrusions, which is a more direct measure of sympathetic activity, did differentiate the two groups.
