Return of fear: The role of inhibition

In a previous study investigating the relationship between subjective, physiological and behavioural changes during treatment of specific phobias, a marked between-session increase was found in subjective fear after high, but not after low intensity phobic stimulation although the groups showed similar fear ratings and heart rates immediately after treatment (Grey et al, 1979). It was hypothesized that the high intensity stimulation led to ‘treatment fatigue’; a state of deactivation, the recovery from which led to a return of fear.In this study high intensity in vivo stimulation was used for the treatment of phobic subjects under conditions of distributed and massed practice. No differences emerged between treatment conditions. A small group of Ss with a conspicuously high heart rate (mean level 120 bpm) when rating zero fear, showed a significant increase in fear after one week's interval, although they had shown similar improvement to the Ss during treatment. Subjects in both treatment conditions showed lower heart rate at all post-treatment assessments than pre-treatment. The high initial heart rate Ss continued to have higher heart rate than other Ss throughout the experiment, although they showed a decrease after treatment. It was only these Ss with desynchronously high heart rate, i.e. high heart rate with zero fear ratings, who suffered a return of fear, whereas high heart rate during high fear did not predict either response to treatment or return of fear. A further finding was a lack of correlation between the behavioural and physiological indices of fear, namely, between distance and heart rate at high levels of fear.