A recent study showed what office workers around the world already knew — the promise of pizza is good for productivity. The discovery was made by psychologist Dan Ariely and explained in further detail in his book Payoff: The Hidden Logic That Shapes Our Motivations. Pizza proves to be the biggest motivator — more than even cash or compliments. Ariel’s experiment used four separate groups of employees at an Intel semiconductor factory in Israel. Workers were to receive rewards for their increased productivity. One group was offered a bonus payment of about $30. Another group was offered pizza. A third group would receive a compliment from their boss, and the fourth group was offered nothing. Ariel found that cash and compliments didn’t do as much to motivate the workers as the pizza — initially. The Cut reported that after the first day, the pizza group increased productivity by 6.7 percent over…