A customer at an Apple store asks for the latest iPhone in black, but then suddenly changes his preference to white when he sees everyone else buying black . . . Although the child knows she shouldn't press the big red button, she finds her hand inching toward it. . . . In some cultures, young men and women who decide to marry know that they will see each other in person for the first time on their wedding day. How did these people make their choices? How do any of us make vital and mundane choices?