Recent advances in imaging have revealed that false memories can be held by the very same cells that hold accurate ones, but we don’t have much information about how false memories get there in the first place. A recent study published in PNAS provides some insight into this issue, finding that false memories may arise from similarities among the items being remembered.

In neuroscience, false memories don’t necessarily refer to a sensational memory that might land you on a daytime talk show. Typically, neuroscientists are more interested in banal false memories. For example, a classic experiment in false memories involves showing a subject a series of words related to the winter season, like ice, snow, wind, etc. In this paradigm, even if subjects aren’t shown the word “cold,” they are still likely to remember having seen it. This is a classic false memory.

Neuroscientists have suspected that this type of false memory arises because the word “cold” is similar conceptually to the list of winter words that the subject did see. Even though the cognitive mechanism that causes this phenomenon (called conceptual similarity) is theoretically understood, however, its neural underpinnings have not been widely explored. Using a combination of the word-recall experiment described above and fMRI scans that could track the brain activity of the participants, the authors of this paper have begun to identify some of what’s behind the false memory effect.