From The New York Times:
In a recent experiment, psychologists at Yale altered people’s judgments of a stranger by handing them a cup of coffee. The study participants, college students, had no idea that their social instincts were being deliberately manipulated. On the way to the laboratory, they had bumped into a laboratory assistant, who was holding textbooks, a clipboard, papers and a cup of hot or iced coffee — and asked for a hand with the cup. That was all it took: The students who held a cup of iced coffee rated a hypothetical person they later read about as being much colder, less social and more selfish than did their fellow students, who had momentarily held a cup of hot java.
New studies have found that people tidy up more thoroughly when there’s a faint tang of cleaning liquid in the air; they become more competitive if there’s a briefcase in sight, or more cooperative if they glimpse words like “dependable” and “support” — all without being aware of the change, or what prompted it. Psychologists say that “priming” people in this way is not some form of hypnotism, or even subliminal seduction; rather, it’s a demonstration of how everyday sights, smells and sounds can selectively activate goals or motives that people already have.
More fundamentally, the new studies reveal a subconscious brain that is far more active, purposeful and independent than previously known.