How does science explain déjà vu? It's a brain glitch with a purpose.

Do you know that strange sensation of walking into a room and feeling like you've been there before, even though you know you haven't? Or when you hear someone say something for the first time, but there's a certain familiarity to it that gives you pause? That's déjà vu–a phenomenon that's not well understood, but scientists have some ideas. Déjà vu is the eerie feeling that you have had the same novel experience before. It's a spontaneous, elusive sensation that reveals the workings of consciousness, allowing us to see the separation between what we feel and what we know to be true, explains Akira O'Connor, a psychologist and senior lecturer at the University of St. Andrews School of Psychology and Neuroscience.