[Avoidance learning in a social situation- extinction resistance and defense reaction under stress. A pilot study].

Two successive experiments were conducted resulting from observations of the stability (resistance to extinction) of avoidance reactions and the manifestation of such reactions beyond the specific avoidance conditions in which they were acquired: a) 15 subjects were set the task to avoid an aversive acoustic stimulus for a helpless experimental partner. They could achieve this by reacting with contraction of either the forearm or the calf muscles in a difficult discrimination task. The stability of these avoidance reactions was assessed on different levels of forced extinction. Measures taken were HR, GSR and EMG of the avoidance reactions. Specific courses of the two autonomous measures evolved (Fig. 1,2). 14 of the 15 experimental subjects showed the avoidance behaviour during all phases of forced extinction. b) Six weeks after the experimental subjects had acquired the motor avoidance reactions all subjects were exposed to a relatively unspecific stress situation. Comparisons between experimental and control group (which consisted of the experimental partners) showed a tendency but not a significant difference as far as the reaction of the calf muscles was concerned. Contraction of the forearm muscles, however, occurred significantly more often in the experimental group. The subjects executed these reactions without being aware of it.