Princeton University scientists have found a new way of tracking people’s mental state as they recall previous events — often called mental time travel.

The neuroscientists say their findings will aid efforts to learn more about how people mine the recesses of memory and could have a wide-ranging impact in the field of neuroscience, including studies of brain disorders such as Alzheimer’s disease.

The researchers showed nine participants a series of pictures and then asked them to recall what they had seen. By applying a computerized pattern-recognition program to brain scanning data, the researchers were able to show the participants’ brain state gradually aligned with their brain state from when they first studied the pictures. This supports the theory memory retrieval is a form of mental time travel.

In addition, by measuring second-by-second changes in how well participants were recapturing their previous brain state, the researchers were able to predict what kind of item the subjects would recall next, several seconds before they actually remembered that item.

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