Emotions have been described by some theorists as discrete and consistent responses to internal or external events which have a particular significance for the organism. Emotions are brief in duration and consist of a coordinated set of responses, which may include verbal, physiological, behavioural, and neural mechanisms. Psychotherapist Michael C. Graham describes all emotions as existing on a continuum of intensity. Thus fear might range from mild concern to terror or shame might range from simple embarrassment to toxic shame. Emotions have also been described as biologically given and a result of evolution because they provided good solutions to ancient and recurring problems that faced our ancestors. Moods are feelings that tend to be less intense than emotions and that often lack a contextual stimulus.

Who described the concept of a continuum of intensity?