Locus of control of behaviour: is high externality associated with substance misuse?

Personal control and responsibility are key themes in the therapeutic use of 'motivational interviewing'. This popular method of counselling has suggested that clients need to believe they have a significant degree of control over their behaviour if they are to make progress. Using a well validated psychological test on locus of control of behaviour, our research sought to establish whether active misusers really believed they had less personal control than non-misusers. To establish this a sample of misusers was tested and compared with three diverse, comparable groups. Possible confounding factors such as age, sex and class were controlled for. T tests established a significant difference between the active misusers and the other sampled groups. Further, a regression analysis of variance, calculated to explain the differing external scores offered no reasonable explanation as far as age, sex and class were concerned. Alternatively, self diagnosed substance misuse accounted for 23% of the variation in scores. We concluded, therefore, that high externality scores are a good indicator of active misusing behaviour and that beliefs about personal control are important to address, if one is to increase the chances of a positive client outcome.