Scientists have finally explained why déjà vu happens, revealing that it is a memory "error check" rather than a psychic glitch. The sensation occurs when the brain detects a familiar feeling without any specific memory to back it up, causing a conflict between familiarity and recollection. This conflict is a sign that the brain's control system is doing its job by flagging the experience and preventing false memories from being accepted as true.

Déjà vu involves a conversation between memory hubs in the medial temporal lobe and control hubs in the prefrontal cortex. The conflict-monitoring process is like a referee double-checking a spreadsheet, ensuring that memories are accurate. While déjà vu may be more common in younger adults and decline with age due to changes in memory systems, it serves as a reminder that the brain is both efficient and cautious, striking a balance between quick familiarity and verifying facts.