Perceived control (also referred to as an internal locus of control orientation, perceived personal control, perceived competence, self-efficacy or a sense of mastery) has been defined as the belief that one can determine one's own internal states and behaviour, influence one's environment and/or bring about desired outcomes (Wallston, Wallston, Smith & Dobbins, 1987). If people say that things are under their control, they are saying that they are able to determine or influence important events or situations (Walker, 2001), including their own actions or those of other people.

Perceived control has long been ‘recognized as a central concept in the understanding of the relationships between stressful experience, behaviours and health. Experimental investigations indicate that control over aversive stimulation has profound effects on autonomic, endocrine and immunological responses, and may influence the pathological processes implicated in the development of cardiovascular disease, tumour rejection and proliferation, and the acquisition of gastrointestinal lesions’ (Steptoe & Appels, 1989).

It is critical to understand the distinction between actual control – the objective responsiveness of an event to influence by human or other factors – and perceived control which might bear little correspondence to reality. The mental and physical health benefits which have been associated with control have been related more to the subjective perception that control exists than to the objective determination of that control. A person's wellbeing is a function of the degree to which they feel in control, not how much they are in control.