For the behaviourist, a person's observable behaviour is the primary object of consideration when assessing a mental condition such as depression. Factors that may shape depressive behaviour, including genetics and brain chemistry, are de-emphasised in favour of environmental factors.
Clinical depression is characterised by feelings of sadness and hopelessness sufficient to interfere with normal functioning. Those with depression also may experience changes in eating and sleeping habits, social withdrawal, loss of interest in activities once thought to be pleasurable and thoughts of suicide.
Behaviorism is a psychological theory that suggests that human behaviour is adapted by learning. According to MentalHelp.net, behaviourists think depression is a learned behaviour that is possible to unlearn.
Under behaviorism, a person may become depressed because of a lack of positive reinforcement for their behaviour and actions. A behaviourist therapist may help a depressed person adapt new behaviours that will lead to more positive outcomes.
According to behaviorism, some depressed people may receive positive reinforcement such as sympathy and attention for depressive behaviour, prolonging the depression.
According to MentalHelp.net, behavioural therapy for depression focuses on helping patients learn and practice new skills to avoid depression, as opposed to examining unconscious factors that may cause depression.