Smells are among the best examples of influences acting upon our unconscious. In fact, their power to influence is greatest when we cannot consciously detect them. The article, “Scents and Sensitivity” (The Economist, December 8, 2007 edition), discusses the work of Wen Li from Northwestern University. The conclusion from her research report, “Subliminal Smells Can Guide Social Preferences”, begins:
. . . the time-honored belief that scents play an important role in human social settings appears to withstand scientific scrutiny. Furthermore, our data suggest that it is in the absence of conscious awareness that odors best exert their effects.
What Li found was that smells that were only barely detectable by bloodhounds influenced how people rated other people’s likeability. In other words, if the smell was pleasant, people tended to like the picture of the person shown; if it was unpleasant then they tended to dislike. However, as the article mentions, “when participants did consciously perceive a smell, its effect on face-perception disappeared.”
This is the important point from Li’s work: it’s possible to defend ourselves from subliminal influences by being more aware and conscious of them. We do this by accepting that people can influence us intuitively and subconsciously even if we believe they can’t and raising our awareness as to how these influences work. People don’t need to be conscious of what they’re doing and don’t need to be right about what they say to influence us.
However, what encourages us to fall persistently for these influences is the desire to believe that we are in control of our thoughts. The more we believe this, the more likely we are to fall under the spell of subliminal influences such as unconscious smells.
Related link: Subliminal Smells & Subliminal Persuasion: provides a good summary of Li’s work and arguments prior to it against the existence of subliminal smells.