Have you ever been bugged by an incomplete or interrupted task that keeps popping into your thoughts? Or felt the need to keep reading a book you’ve nearly finished, or tune in to the next episode of a TV program that finished on a cliffhanger?
If so, you’ve experienced the 'Zeigarnik Effect’, a phenomenon first reported in the 1920s by Lithuanian psychologist Bluma Zeigarnik. She noted that restaurant waiters seemed to have an uncanny ability to remember complex orders whilst the food is being prepared and served, but couldn’t recall anything about the order once the diners had paid. She theorised that they kept the information in their short term memory and unconsciously erased it when it was no longer useful, never having made it as far as their long term memory.