53: (top-bot) Royalty Free/Getty Images, Manfred Ruiz/Getty Images; 66: (L and R) Title page and p. 229 from Predictably Irrational: The Hidden Forces That Shape Our Decisions by Dan Ariely. Copyright © 2008 by Dan Ariely. Reprinted by permission of Harper Collins Publishers; 68: Reproduced with permission. Copyright ©2010 Scientific American, a division of Nature America, Inc. All rights reserved; 80: (L and R) Courtesy of Nobel Media AB; 89: (top-bot) Courtesy of Pew Internet, Courtesy of Peter Urban; 172: (top-bot and L-R) Royalty Free/Getty Images, Royalty Free/Getty Images, iStock photo, Royalty Free/Getty Images; 173: Royalty Free/Getty Images; 235: Courtesy of David England.