Strapped-for-cash startup founders who need to motivate their teams to move mountains, listen up. Got $30? Great. That's all you need to make your employees more productive. But don't hand out cold, hard cash. Instead, tell them you'll buy everyone pizza if they work hard.

A productivity experiment found that pizza was a fantastic motivator for increased productivity. Unlike many scientific studies, this one was not performed on rats. Behavioral economist Dan Ariely performed the experiment on actual human beings with actual jobs whose actual work performance could be measured by actual pizza.

He details the results in his forthcoming book Payoff: The Hidden Logic That Shapes Our Motivations. Science of Us shares details about how Ariely performed the experiment.

How the pizza workplace motivator study was conducted

Ariely selected factory workers who assemble computer chips as his lab rats because their level of productivity could very clearly be measured. The workers were promised one of three rewards if they had a productive workweek: pizza, compliments, or a cash bonus of around $30. A fourth unlucky group, the control group, was promised nothing.

After the first day, those who had been promised pizza had been more productive than the control group by 6.7 percent. And here's what's even more surprising. Those who were promised a compliment -- which was simply a text message from the boss that said "Well done!" -- were neck-and-neck with the pizza group at 6.6 percent. The worst motivator? The cash bonus group, whose productivity increased only 4.9 percent compared with the control.

And then things got even more surprising. Over the course of the work week, the productivity of the workers who were promised a cash bonus plummeted. "For the week overall, the cash bonus ended up costing the company more and resulted in a 6.5 percent drop in productivity," reports Science of Us. "From the employer's perspective, a cash bonus is worse than offering no incentive at all."

So the tasty takeaway from Ariely's work? Don't worry if you can't match Google salary and perks. Instead, work on communicating to your employees that you appreciate their hard work. Get a pizza delivered to say thanks. And while you're at it, pick up a lovely cheese pizza, just for you. Your productivity will thank you.