Memory is malleable, dynamic and elusive. When we tap into our memories, where is the line between fact and fiction? How does our memory play tricks on us, and how can we train it to be more accurate? In this hour, TED speakers discuss how a nimble memory can improve your life, and how a frail one might ruin someone else's. Forensic psychologist Scott Fraser argues that in a criminal trial, even close-up eyewitnesses can create "memories" they may not have seen. Nobel laureate Daniel Kahneman explains how our experiences and our memories perceive happiness differently. Writer Joshua Foer shows how anyone can achieve amazing feats of memory, including him.