Date of Award


Degree Type


Degree Name

Doctor of Philosophy


School of Psychology and Social Science


Computing, Health and Science

First Advisor

Professor Craig Speelman

Second Advisor

Dr Greg Dear


With unipolar depression one of the most disabling illnesses in the world, it is important to appropriately conceptualise this disorder in order to inform research, diagnosis, and treatment. While many psychological theories of depression include constructs of polarity, most research and diagnostic criteria have focused on a single dimension that concentrates on the presence of negative symptomatology. This is reflective of an illness model of mental health that predominantly considers the presence of negative symptoms in terms of mood, cognitions, behaviours, and overall functioning. Nevertheless, there is strong research evidence indicating that positive and negative aspects of psychological functioning are largely separate systems that both play a part in the assessment of a person’s psychological well‐being. It was the intention of this research to more closely examine the existence, influence, and assessment of a positive dimension of psychological functioning with regard to depression. Nevertheless, the current research did not reveal any differential influence of positive psychological functioning on the development of depression. Indeed, the impact of depression appeared to be so significant that it served to overwhelm many aspects of positive psychological functioning – making the point of whether they are separate systems moot in a practical sense. Possible mechanisms to account for this differential impact are discussed, along with suggestions for future research.