The following text discusses cognitive psychology.

Cognitive dissonance describes the mental discomfort that arises when beliefs, attitudes, or behaviors conflict. Festinger's classic study found that participants paid only $1 to lie about a boring task later reported finding it interesting—more so than those paid$20. The $1 payment was insufficient external justification; to reduce dissonance, participants changed their attitude. Those paid$20 could attribute lying to external reward, experiencing less dissonance. This finding has implications for persuasion: sometimes insufficient incentives produce greater attitude change than larger rewards because they force internal justification.