Jamming the Signal: Better Living Through Subliminal Messages

by John Ohno

A little over ten years ago, I discovered a program that shipped with my screensaver package called xsublim. This program (which no longer ships with xscreensaver, and in fact no longer builds) takes a text file, splits it into individual words, and then displays each word on random place on your screen for a tiny fraction of a second. Experimenting with it led me on an interesting path through the backwoods of cognitive science.

XSublim was written as a lark, and by default it will display slogans from 1984 and They Live. However, in the half century since pop-culture’s ideas about subliminal messages crystallized, research has progressed: contrary to the media depictions of frightening hypnotic mind control, subliminal messages have only weak and difficult-to-predict effects, and complicated messages (longer than one or two words) are barely processed at all.

I’m mostly interested in the mind-expanding (rather than mind-controlling) potential of subliminal messages — an area   they are ultimately better suited for. The point of greatest interest is the way that subliminal messages bypass conscious awareness and therefore do not require conscious attention: subliminal learning is a little bit like earning royalties or interest, in that the returns may be small but the effort-to-return ratio is nearly zero. Replacing a week of active study with a year of passive study is a no-brainer.

Mechanism of action

When we talk about subliminal messages, what we’re really talking about is what cognitive scientists call ‘priming’: a weak nudge that inclines us toward particular associations. Priming creates a sense of familiarity and attractiveness — flash faces on a screen, and those faces will be rated as more attractive during a survey. Priming also encourages similar ideas: people who see the word “water” flashed on a screen will be slightly more likely to interpret “bank” as “river bank” than as “financial institution” and those who see “doctor” will respond slightly more quickly to medical-related prompts — a concept known as “spreading activation.” It does this just by seeding a pattern in working memory — ‘priming the pump’ and making related thoughts flow more easily.

This makes it not terribly useful for advertising. A subliminal ad can make people who are currently thirsty slightly prefer Coca Cola, but it can’t get them to buy a case when they already have Sprite in the fridge. Similarly, the impulse is so weak that it can’t be used to get people to act out of character (you can’t be subliminally instructed to kill the president, although if you are playing a first person shooter video game it might be able to get you to shift your target one in a thousand times). If we want to squeeze utility out of subliminal messages, we need to be a little more creative.



Subliminal exposure can produce a sense of familiarity, which can be used to aid learning. Even though seeing the contents of a math textbook subliminally a million times will not let you skip the math class, it will make the terms and patterns seem more familiar, less imposing, and easier to remember — so later study will be easier. Seeing the contents of the textbook after class can help keep the ideas in memory. I typically begin to display the ebook versions of books I intend to read months in advance, continuously — making the actual task of reading them much faster, when I finally get around to it. I have had dense philosophical texts in circulation for years. Read more “Jamming the Signal: Better Living Through Subliminal Messages”