Evaluation of a psychophysiological model of classical fear conditioning in anxious patients.

Skin conductance variables have been compared in 30 anxious patients and 30 controls to investigate the extent to which anxiety is associated with increased autonomic arousal, reduced habituation or enhanced aversive conditioning. Skin conductance level, variability (spontaneous fluctuations) and response amplitudes to tones were significantly greater in patients than controls. Habituation of skin conductance responses to a series of ten innocuous tones (80 dB, 1 s) did not differ between the groups. Aversively conditioned skin conductance responses were measured to a further series of ten tones after a conditioning trial in which a loud white noise (100 dB) followed tone 11. All subjects showed enhanced (conditioned) responses to the tones after the conditioning trial, but patients did not show greater conditioning than controls. The results indicate that anxious neurotic out-patients have greater sweat gland activity and reactivity than controls but fail to demonstrate differences in central mechanisms of habituation or conditioning.