Pattern recognition, recency and familiarity biases can impact our perceptions and responses. If you're hiring a librarian and the applicant doesn't look like your preconceived notion of what a librarian looks like, does that impact your assessment of them? If your high school bully was named Toby, does that affect your impressions of other Tobys you meet later? On average it does. Don't be average.
A quick snapshop of a couple of studies on how our behaviuour can be nudged by others through small positive actions.