Discrimination between intensity and affective pain descriptors: a psychophysiological evaluation

The current study utilized a differential classical conditioning paradigm to test subjects' abilities to autonomically differentiate between pain descriptors that had previously been designated as belonging to the intensity or affective dimensions of pain perception. Twenty-one subjects were first tested for differences in spontaneous skin conductance responses (SCRs) and possible habituation to visual presentations of 23 intensity or affective pain descriptors. The classical conditioning procedure consisted of 46 12-sec visual trials. Each of the 23 pain descriptors was presented twice to each subject. Results indicated no differences in spontaneous SCR to intensity or affective descriptors and a clear habituation of response across trials. Results also indicated that the utilization of a differential classical conditioning paradigm produced an overall difference in SCR to the two sets of pain descriptors. The intensity-conditioned subjects demonstrated greater SC responsivity (P less than 0.0004) to intensity-related descriptors than to affective descriptors, and affective-conditioned subjects displayed greater skin conductance responsivity (P less than 0.0004) to affective pain descriptors than to pain intensity descriptors. These results provide psychophysiological support for a multidimensional conceptualization of pain and suggest the utility of classically conditioned autonomic responses in the further development and refinement of verbal pain descriptor scales.