In a study at Northwestern University, volunteers who were asked to wear white lab coats did better on tests than those who weren't. Similarly, according to this Forbes article about the psychology of masks and costumes, people "jump higher or hit the golf ball further using gear made from their favorite brand. People play better or at least have the confidence to play better when donning the jerseys or shoes made by their preferred brands."
The idea of a mask or costume can be extended to things we buy as a way to signal our roles in society.
From the article:
Using machine learning to analyze their purchases, a team of researchers at the University of Chicago could predict the age, sex, race, political affiliation, age, and socioeconomic level of research participants.
For gender, this is easy – men rarely buy eyeliner, and women rarely buy men's aftershave. Others are more surprising. For instance, the most accurate predictor of someone being white is whether they buy English Muffins. Similarly, watching The Big Bang Theory is also a key indicator of one's Caucasian descent. Moreover, owning a fishing pole is the best predictor of being politically conservative. And the fast-food brand most closely associated with being conservative? Arby's.