What happens when your behavior and your beliefs don't match up? You can't change what actually happened to clear up the cognitive dissonance, but memories and opinions are infinitely malleable.
Good Cop, Bad Cop
A mild threat works better than brute force. In one study, children persuaded to avoid a toy fancied it less later only when the threat of punishment had been light. The gentle touch allowed kids to feel it was (partially) their choice to obey, and they justified forsaking their object of desire by deciding it wasn't such a hot item to begin with.
We'll go so far as to distort physical perception to calm our qualms. Students clad in an embarrassing Carmen Miranda getup (fruit hat, grass skirt, coconut bra) were either softly pushed or forced to cross a campus quad. The first group estimated the walk to be shorter to justify their choice.
Monkeys and preschoolers revise opinions too. After having to choose between two candies or (in the kids' case) stickers they'd expressed equal preference for, subjects downgraded their opinion of the road not taken, perhaps as a defense against "buyer's remorse."
Grading the Grade
Students' ratings of instructors are uncannily linked to the grades they received, but new research shows that returning the punch is not about punishing the professor. Rather, withering reviews deflect the blame; someone's got to be at fault for that D, and it's not me.
Mind the Gap
Years ago, two Sudanese tribes began removing their kids' permanent front teeth, just in case of lockjaw. How to justify the painful procedure as the incidence of lockjaw diminished? The tradition endures today because the groups now see beauty in the gap-toothed grin.