Hack82.Subliminal Messages Are Weak and Simple

Hack 82. Subliminal Messages Are Weak and Simple

Subliminal perception sneaks underneath the level of consciousness and can influence your preferencesbut only a little.

Being exposed to a photograph for two-hundredth of a second can't really be called seeing, because you won't even be consciously aware of it. But having a photo flashed at you like this works it into your subliminal perception and means that next time you see it you'llvery slightly, mindprefer it to one you've never been exposed to before.

9.3.1. In Action

Proving that mere exposure can change your preferences isn't easy to do at home, so it's best to look at the experiments. Robert Bornstein and Paul D'Agostino exposed a group of volunteers to images, either photographs or unfamiliar shapes, and then asked each person to rate the images according to how much he or she liked them.¹

If you were one of those volunteers, you'd have spent 5-10 minutes at the beginning of the experiment being exposed to images for only 5 milliseconds each. That's a tiny amount of time for vision, only as long as a quarter of one frame of television. Exposed to a picture for that long, you're not even aware you've seen it. As a volunteer, you could be shown the picture later to look at, and it's as if you're seeing it for the first time.

When you're asked which images you prefer out of a larger selection, you'll rate images you were exposed to but can't recall seeing higher.

9.3.2. In Real Life

The rating exercise is a little like the game Hot or Not (http://www.hotornot.com) but with some of the photos flashed up at you faster than you can make them out beforehand. In Hot or Not, you see a photo of a person and rate it: 10 being Hot and 1 being Not. The web page then immediately reloads with another photo for you to rate, and you can also see how your score on the previous photo compared to what everyone else said.

All else being equalall the photos being equally attractivelet's pretend you're rating all the photos 5 on average.

If you'd had the photo flashed up at you 20 times in that initial batch of image exposure, for only 5 ms each time (less than a tenth of a second in total!), you might rate that photo not a 5, but a 6.

Given this works for mere exposure, below the level of awareness, the same effect should come about if the photo is presented in some other fashion that doesn't require your attention. Thinking of Hot or Not still, incorporating a photo into a banner ad (now we're all trained not to look at banners) for a few pages before you actually have to rate the photo should mean you like the photo more.

M.W.

9.3.3. How It Works

Two things are going on here. The first is subliminal perception. The visual system has just enough time to get the image presented into the brain, but not enough to process it fully to conscious awareness. In addition to subliminal perception, there is a priming [Hack #81] effect. Whenever some perception reaches the brain, the neurons that are involved in that representation persist in their activity for a while, and if you experience that thing again, your neurons respond more readily to it.

So when your perception of a particular face has been subliminally primed, when you see the photograph again, properly, your brain reports a very slight sense of familiarity. But because you can't actually recall seeing the photo before, you misinterpret this feeling as preference: you like the face in the photo more than you otherwise would have done.

Mere exposure is the phenomena behind the urban legend of subliminal perception, in which the words "Hungry? Eat popcorn" repeatedly flashed up (too fast to consciously see) during a movie is supposed to result in a colossal increase in popcorn consumption. It's correct inasmuch as repeated exposures lead to a stronger priming effect, and therefore a slightly stronger preferencebut that's all.

The experiments that led to the "Hungry? Eat popcorn" legend were fabricated in the 1950s.² What mere exposure can do is slightly influence you if you're undecided about which goal to pursue. Being exposed to a picture of a particular chocolate bar could encourage you to pick out that bar if you're standing at a counter with a dozen different bars a few minutes later. What mere exposure can't do is give you an overpowering hunger to stand up, walk off, and find that chocolate, or even make you buy chocolate if you've already decided you want chips.

Nor can mere exposure influence you with complicated instructions. There's barely enough time for the image of the three words "Hungry? Eat popcorn" to bump through your visual production line, to make a representation in your brain, but certainly not enough for the words to be understood as a sentence. A photograph, a shape, or a single word is as far as it goes.

To be honest, subliminal advertising doesn't seem worth the effort for such a small effect. Given that pretty, barely clothed people doing suggestive things on TV sell products so well, I don't see a shift to subsecond commercial breaks any time soon. Unless, of course, that's what the images are telling me to say.

M.W.

9.3.4. End Notes

1. Bornstein, B. F., & D'Agostino, P. R. (1992). Stimulus recognition and the mere exposure effect. Journal of Personality and Social Psychology, 63(4), 545-552.

2. The Snopes Urban Legends Reference page on subliminal advertising (http://www.snopes.com/business/hidden/popcorn.asp) gives more of the "eat popcorn" story. James Vicary, who made the claims in 1957, came clean some time later about the results of his experiments, but the concept of subliminal advertising has been doing the rounds since.