Fear : measurement and modification.
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
The avoidance and response prevention (RP) literatures are reviewed. This review highlighted a number of persistent issues, revealed a need for the development of sensitive fear assessment measures and showed a number of parameters that enhance response prevention's efficacy in reducing conditioned fear. This thesis examined (i) a number of RP parameters across escape-from-fear and passive avoidance baselines, using in the latter situation, multivariate fear assessment measures; and (ii) the psychopharmacological actions of the benzodiazepine, diazepam, and beta-adrenergic blockers, propranolol and atenolol, across passive avoidance, conditioned suppression of licking and signal detection behavioural baselines. In experiment one, escape-from-fear behaviour was found to be insensitive to 100 - and 200 - non-reinforced 5 second CS presentations (RP). Massed RP was reported to be superior to distributed RP and protracted RP (2 hr) more efficacious than 1 hr RP in reducing conditioned fear and hastening avoidance extinction in experiment two. Social facilitation of RP (experiment three) enhanced RP effects when assessed by the time fear assessment measure but had less effect on RP when assessed by the approaches and first entry latency measures. This differential sensitivity of the fear assessment measures was also reported for diazepam, propranolol and atenolol - assisted RP (experiments three and four). Experiment five examined the separate and combined administration of diazepam and propranolol on disinhibiting licking behaviour. Diazepam was more effective than the combined treatment, which in turn was more effective than propranolol alone, with atenolol having little effect in disinhibiting licking behaviour. Experiment six established a signal detection behavioural baseline which was used to independently assess possible diazepam - and propranolol-induced changes in stimulus discrimination from possible drug-induced changes in response-bias (experiment seven). Both diazepam and, propranolol failed to affect response bias, whereas stimulus discrimination was attenuated by propranolol but unaffected by diazepam administration. The response prevention results were discussed in terms of a modified two process theory presented in chapter two, which emphasised the relative sensitivity of and the relationship between the fear assessment measures in discriminating RP effects on conditioned fear and avoidance behaviour. The drug results were discussed in terms of the respective modes of anxiolytic action of the benzodiazepines and beta-adrenergic blockers. This signal detection results were discussed in terms of matching model and signal detection analyses of choice behaviour. Implications of these results to avoidance theory and research as well as to the assessment and treatment of fear motivated human neurotic behaviours were discussed with suggestions for future research being presented.