You’re at a party. It’s pretty relaxed, people are chatting and you’re sitting in the living room with a friend. All of a sudden, “Last Friday Night” booms through the speakers. In a second, everyone is on the dance floor. “Yeah, we danced on tabletops, and we took too many shots / Think we kissed but I forgot / Last Friday night” Throwback after throwback plays, and by the end of the night your throat hurts from singing and you’re giddy from laughing with your friends. But what makes just one song capable of completely shifting the mood of so many people for an entire night? That’s a great question — it all has to do with the effect of nostalgia!