Researchers engaged subjects in a taste-test of a new jam.
Once subjects declared a preference, the researcher gave them another taste of their preferred jam before asking what they preferred about it.
Unbeknownst to the subjects, the jam jar had a secret divider permitting the researcher to present them with the jam they did not prefer.
The vast majority did not notice the switch, and had no trouble generating a list of reasons for their “preference.”
The experiment was repeated with headshot photos rated for attractiveness, and produced the same results.