Research highlight

The memory of things past

Nature Neuroscience

February 9, 2009

People can recognize a previously seen image, even when they have no conscious awareness of having seen it, finds a study online in Nature Neuroscience. Such recognition was thought to be associated with conscious, explicit memory, rather than unconscious, implicit memory. The study also finds that a specific pattern of electrical activity in the brain is associated with such unconscious recognition memory.

Joel Voss and Ken Paller showed people images, asking them to remember them, despite the distraction of a simultaneous numerical task. In a later test session, previously seen images were presented along with new similar images. Participants correctly recognized the previously seen image most of the time, although they were likely to report that they were guessing, not that they remembered the image itself. This suggests that the people can recognize an image, even without conscious awareness of it.

Recordings of electrical signals related to brain activity during the recognition test showed a distinct response when participants recognized an image without conscious awareness. These results suggest that implicit memory might contribute to recognition, which had been thought to require an explicit awareness of having previously seen something.

doi: 10.1038/nn.2260

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