 A notable advancement was Arnold's idea of intuitive appraisal in which she describes emotions that are good or bad for the person lead to an action.For example, if a student studies hard all semester in a difficult class and passes the tough mid-term exam with an "A", the felt emotion of happiness will motivate the student to keep studying hard for that class.Emotion is a difficult concept to define as emotions are constantly changing for each individual, but Arnold's continued advancements and changing theory led her to keep researching her work within appraisal theory.