Friday, March 07, 2008

Neuroscience: How far has “mind reading” got?

Well, according to a recent article in Nature News by Kerri Smith you can figure out what a person is seeing, if you already know what the possible sights are. But you won;’t know what the person thinks of it.

In the experiment, the brain activity of two subjects (two of Gallant’s team members, Kendrick Kay and Thomas Naselaris) was monitored while they were shown 1,750 different pictures. The team then selected 120 novel images that the subjects hadn’t seen before, and used the previous results to predict their brain responses. When the test subjects were shown one of the images, the team could match the actual brain response to their predictions to accurately pick out which of the pictures they had been shown. With one of the participants they were correct 72% of the time, and with the other 92% of the time; on chance alone they would have been right only 0.8% of the time.

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The next step is to interpret what a person is seeing without having to select from a set of known images. “That is in principle a much harder problem,” says Gallant. You’d need a very good model of the brain, a better measure of brain activity than fMRI, and a better understanding of how the brain processes things like shapes and colours seen in complex everyday images, he says. “And we don’t really have any of those three things at this time.”

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But it will be a long time yet before it applies to his own work, he says, because “we don’t have a good enough model for intentions".

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