When shopping, researchers believe if you choose one option over the other we are placing more value on the options we choose and less value on the options rejected.

Researchers believe this theory exists because of cognitive dissonance. Cognitive dissonance is when an individual makes a selection between two options that he or she feels the same about, but it creates a sense of conflict, guilt or doubt.

Though this theory has been demonstrated in several studies, researchers have only examined preference change right after an individual has made a decision. Researchers from the University College London studied whether choice-induced changes in preference are long-lasting or short-lived.

Lead researcher Tali Sharot and her colleagues asked 39 undergraduates to rate the desirability of 80 different vacation destinations. They rated how happy they would be if they were on vacation at that location. They were then offered other similar vacation destinations and instructed to choose which destination they would prefer. The students rated their destinations after making their choices and did so once again three years later.

The students either made the choice themselves or a computer helped instruct their choice. Sharot found the act of choosing between two similar options can lead to lasting changes in preferences. Students rated their vacation destinations more desirable immediately after choosing the locations, and again, three years later.

However, researchers observed if and when a change in preference occurred it was when participants made their original choice themselves. There was no change in choice when the computer instructed their choice.

Sharot believes these findings may be able to have lasting effects for several fields such as economics, marketing and interpersonal relationships.

With the presidential elections a few short weeks away, Sharot mentions constantly favoring one candidate over the other may embed this particular preference for a long period of time.

The study was published in the journal Psychological Science.