Functional approaches rely on understanding what roles emotions play in humans and examining that role in animals. A widely used framework for viewing emotions in a functional context is that described by Oatley and Jenkins who see emotions as having three stages: (i) appraisal in which there is a conscious or unconscious evaluation of an event as relevant to a particular goal. An emotion is positive when that goal is advanced and negative when it is impeded (ii) action readiness where the emotion gives priority to one or a few kinds of action and may give urgency to one so that it can interrupt or compete with others and (iii) physiological changes, facial expression and then behavioural action. The structure, however, may be too broad and could be used to include all the animal kingdom as well as some plants.