Brain imaging can reveal what a person is thinking.
Source: “Decoding Reveals the Contents of Visual Working Memory in Early Visual Areas”
Stephenie A. Harrison and Frank Tong
Nature 458: 632-635
Results: By analyzing data collected with functional magnetic resonance imaging (fMRI), researchers identified with 83 percent accuracy which of two images a person was remembering.
Why it matters: Previous research has shown that fMRI can reveal which of a number of pictures a person is looking at. But the new study is unique in identifying what the subject viewed before the brain imaging took place. The study also sheds light on where in the brain visual working memories are stored.
Methods: Subjects were briefly shown two successive images of a grating oriented at different angles. They were asked to remember one of the images as an fMRI scanner monitored blood flow in the brain, a proxy for brain activity. Scientists then used specially designed algorithms–derived from previous brain scans of each person–to search for activity patterns that indicated which image the person was thinking of, several seconds after the image itself had disappeared.
Next steps: The researchers are now testing the technique with more-complex visual patterns and exploring ways of using it to gather more information about what people are actively remembering.