Intrusive thoughts : an experimental study of the speed of removal of unwanted intrusive thoughts, and a pilot investigation of pleasant intrusive thoughts

Abstract

This thesis reports the results of two studies examining different aspects of intrusive thoughts. After reviewing the relevant literature, two areas of research requiring further investigation are highlighted, and following this the two independent studies are presented. Study A reports an experimental investigation of the influence of several variables on the speed of removal of unwanted intrusive thoughts in a university student population. The effect of depression, anxiety and distress upon time taken to remove neutral and intrusive thoughts was measured, None of these variables were found to be significant predictors of the speed of removal of intrusive thoughts, and a number of explanations are put forward to interpret these results. A second major purpose of study A was to test the hypothesis that the greater time taken to remove intrusive thoughts compared with neutral thoughts, is better explained in terms of a decreased ability to disattend to the intrusive thought than a decreased ability to access a more pleasant replacement thought. A methodology was devised to test the "disattention hypothesis”, and the results of the experiment were largely supportive of the hypothesis. Study B is a pilot questionnaire survey which investigates the nature and incidence of pleasant intrusive thoughts in relation to unwanted or unpleasant intrusive thoughts. It was found that the incidence of pleasant intrusive thoughts in a university sample was somewhat greater than the incidence of unpleasant intrusive thoughts. The pleasant and unpleasant intrusions were found to have similar patterns of duration, frequency and length of episode and were perceived to be equally controllable. However the pleasant intrusive thoughts were rated as more acceptable. It is argued that the level of arousal engendered by intrusive thoughts is a major determinant of their uncontrollability, and that for both pleasant and unpleasant thoughts, depression and anxiety may act to increase the experienced arousal and hence decrease controllability even further. It is contended that both pleasant and unpleasant thoughts can be considered as "subsets" of normal cognitive processes, and that unwanted or unpleasant intrusive thoughts have at least as much in common with pleasant intrusive thoughts as they do with clinical obsessions.