I. Introduction One of the problems which has confronted investigators of psychophysiology has been the selection of psychological parameters which can be quantified reliably and which can in turn be related reliably to physiological measures.33 Many of the early attempts to relate psychological to physiological functioning compared psychiatric diagnostic groups on various physiological measures; these efforts met with little success, the physiological findings for a given diagnosis often ranging from evidence of marked hypofunction through marked hyperfunction.2,13 More recently attention has focused upon the use of measures of affectivity−particularly anxiety, depression, and anger.* This approach has generally been a more fruitful and reliable one. Nonetheless, methodological and conceptual problems remain. One such difficulty is that affectivity is influenced by the experimental setting itself.29,35,42 Another problem is the tendency of individuals to respond stereotypically, regardless of the stimulus employed.6,8,21,22,31 Yet another problem