Study Shows Human Brain is Capable of Subliminal Conditioning


by Maria Schamis Turner

October 31, 2008

Imagine you are playing a game of poker. Watching your opponent, you have a gut feeling that if you raise the bet, he will fold. You decide to go with your intuition and it works.

Were you just lucky?

According to neuroscientist Mathias Pessiglione, the gut feeling you experienced could be the result of your brain picking up subliminal cues from your opponent and associating them with a positive outcome. Pessiglione uses a poker game as a possible real-life example of the kind of subliminal instrumental conditioning that he and his colleagues at the Institut National de la santé et de la recherche médicale (INSERM), a public research institute in Paris, have demonstrated for the first time in the human brain.

They report the results of a carefully designed study using a system of masked cues matched to win or loss outcomes in the Aug. 28 issue of the journal Neuron.

People in the study were shown pairs of successive images on a monitor: first, the cue, which was flashed very briefly, followed by a second image that acted as a mask. The mask image interfered with the visual processing of the initial cue, so the person’s perception of the cues could happen only subliminally, not consciously. Then the test subjects “won” or “lost” money in a way that matched with one or the other subliminal cues. As the test game continued, the subjects chose the positive outcome more often than if they were choosing by chance alone. After the game, the subjects could not recognize the two cues, confirming that they had not consciously perceived them.

Functional magnetic resonance images (fMRI) recorded while subjects performed the tasks showed significant brain activity in the striatum—a limbic region of the brain that is found in many animals as well as in humans. “The fact that the striatum is involved in this kind of instrumental learning is not new,” says Pessiglione. “What’s new is that it can happen subliminally, even if the subject is not aware of the cue.” He suggests that this subliminal striatal learning could be a mechanism behind the intuition shown in the poker game.

Lesley Fellows, a researcher with the Montreal Neurological Institute who was not involved in the study but who has studied the processes involved in decision making, praised the study design but said that it didn’t address the question of whether this learning underlies hunches. “There are other possible ways that you could have partial information,” she says, “even in a more-explicit conscious form not complete enough for you to be able to fully articulate it, but still be able to make a decision.”

Whether it is the mechanism behind intuition or not, Pessiglione says we shouldn’t be afraid of the striatum.

“There’s a kind of paranoia about subliminal advertising,” he says. “I think we have to see it in a positive way. We have a region in our brains, the striatum, which is able to pick up signals in our environment to guide our decisions. We shouldn’t be afraid because it does it for our good.”

Fellows is not as optimistic. “I think it’s true that we can trust the striatum for matching a long history of reinforcement to a particular pattern,” she says. Whether that means the thing you are about to do is the best choice in that particular instant is less certain. But, she concedes, “If it got us from fish to humans, presumably we can count on it.”