In an experiment, people who saw a picture of a big bowl of soup before eating lunch were less hungry a few hours later than those who saw a smaller bowl, regardless of how much they ate at the meal. stuart burford photography/iStockphoto.com hide caption

itoggle caption stuart burford photography/iStockphoto.com

The Beatles rehearse for that night's Royal Variety Performance at the Prince of Wales Theatre in 1963. Central/Hulton Achive/Getty Images hide caption

itoggle caption Central/Hulton Achive/Getty Images

Research shows that under certain circumstances, we can train ourselves to forget details about particular memories. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Researchers are using MRI scans to learn more about the brains of people with extraordinary memory. iStockphoto.com hide caption

itoggle caption iStockphoto.com