You're standing in a grocery store, with two nearly identical fruits in hand. After a few stressful seconds of weighing and deliberating, you put down the rejected fruit, carefully cradling the chosen one. As you tuck this gem safely into your basket and turn to walk away, you start to question the coloration of the reject-fruit. Was it not as firm or sweet-smelling as the other when you held each in your hands? It probably has some weird bruise on the far side. Yuck.

Good thing you chose the right one because only seconds ago, they looked almost indistinguishable. Even so, how are you certain you've made the optimal decision?

The answer could stem from the theory of cognitive dissonance, which characterizes a measurable state of discomfort that drives someone to take action. The term was coined by social psychologist Leon Festinger in 1957, who defined three aspects of dissonance: one experiences discomfort, takes action, and feels subsequent relief. The effects of cognitive dissonance can be physically measured, with studies showing symptoms of physical distress, such as elevated perspiration, when experiencing cognitive dissonance. Although, this state of distress can be reduced through a series of responses that often occur without conscious awareness. While the most difficult response is altering one’s behavior to reduce dissonance — more common methods include minimizing the importance of the stressor topic, changing existing attitudes or opinions, avoiding conflicting information, and seeking information that agrees with one’s existing point of view.

Cognitive dissonance can often cause people to rationalize their decisions after they’ve acted. In a study on race track betting , people put their odds of winning, prior to betting, at an average of 3.48 on a 7-point scale. Alternatively, those who had just betted put their odds at an average of 4.81. The betters felt more confident after they had committed to their choice, suggesting that the act of deciding triggered rationalization.

Furthermore, individuals who have put time, effort, or money into an endeavor may avoid cognitive dissonance by shunning conflicting information . For instance, a person may choose to continue a relationship even if it soured long ago to avoid the discomfort of taking action, ending the relationship, and feeling like they’ve lost time or energy. On the other hand, dissonance can be so strong that people change their attitudes and take suboptimal courses of action. Economic models of marriage timing show that in the presence of strong social norms to marry early, people were more likely to choose less-than-ideal partners, just to reduce their discomfort with non-adherence to a custom.

Dissonance has profound effects on action and decision making, and understanding it doesn’t mean you’ll never resort to rationalization again. In truth, bowing to cognitive dissonance is not a character flaw, it’s an evolutionary feature of the brain. In nature, cognitive dissonance has been observed in Capuchin monkeys , an evolutionary relative of humans, and has likely been a preserved trait for millions of years. In ancestral environments, dissonance was likely beneficial in urging humans to stay with the pack for safety, and commit to decisions without being paralyzed by ambiguity. While it’s not completely understood why human beings adhere to dissonance, social psychologists theorize that dissonance makes modern people more decisive, and that better problem-solving can occur by eliminating ambivalence and conflict with dissonance-driven attitude changes.

The key to turning off this ancestral overdrive is learning to recognize when that uncomfortable feeling strikes. It's a cue to pause and ask whether you're genuinely satisfied, or just feeling pressure to justify your actions. When you do pause to reflect, remember that your brain will be on your side, helping you support whatever decision you make. The question is whether those supporting reasons truly satisfy you.