This involves not being able to cope with the demands of everyday life (1)
It looks at abnormal behaviour that interferes with everyday life, e.g. unable to maintain basic standards of personal hygiene (1)
Rosenhan and Seligman state that signs of a person failing to function adequately include:
Maladaptive behaviour
Irrational behaviour
Severe personal distress
Behaviour that is dangerous to themselves or others (1)
For example, someone with depression may be unable to keep a job or get up in the morning, therefore showing they have an inability to cope with the demands of everyday life