It turns out pizza can be an intense motivator for people at work. Psychologist Dan Ariely offered four groups of employees at a company in Israel different rewards for productivity. One group was offered a $30 bonus, another pizza, another a compliment from their boss, and the last group was offered nothing. Ariely found the pizza was the biggest initial motivator, coming in ahead of both cash and compliments. In fact, the promise of pizza got employees to be 6.7 percent more productive.