Dan believes that this ‘tailing-off’ could have been avoided if he had run with his initial suggestion of delivering pizza to the homes of employees who reached their daily target: “this way… we not only would give them a gift, but we would also make them heroes in the eyes of their families,” he explains in the book.

But, why do pizza and compliments motivate us more than money and status?

Pennsylvania Professor and author of Give and Take: A Revolutionary Approach to Success, Adam Grant, offered the Wall Street Journal an explanation: “your bonus gets spent, your new title doesn’t sound so important.”

Ariely’s study thus proves that social factors play a larger role in our happiness than money, and his isn’t the first to say so.

This study reveals what really motivates us at work - and it isn’t money