Psychology
The one odd item on a list is the one you'll remember
Show someone a list of similar items with one oddball mixed in, and that oddball is what they remember days later. German psychiatrist Hedwig von Restorff documented this in 1933: a single item standing out from a set of similar ones gets disproportionately better recall than any item in a uniform list. It's now a foundational memory finding, still used in design and advertising.