In psychology, an attitude is an expression of favor or disfavor toward a person, place, thing, or event (the attitude object). Prominent psychologist Gordon Allport once described attitudes "the most distinctive and indispensable concept in contemporary social psychology."[1] Attitude can be formed from a person's past and present.[2] Key topics in the study of attitudes include attitude measurement, attitude change, consumer behavior, and attitude-behavior relationships.[3][4]