Researchers set out to investigate what happens in the brain when we try to remember information that’s very similar to what we already know. This is important because similar information is more likely to interfere with existing knowledge. The study showed that instead of just crowding in, the brain purges an earlier association when that association is revised. In a sense, forgetting is our brain’s way of sorting memories, so the most relevant memories are ready for retrieval. Normal forgetting may even be a safety mechanism to ensure our brain doesn’t become too full.