From grumpy old misers to the wolves of Wall Street, Hollywood has always had plenty to say about the corrupting influence of wealth. But how accurate are the silver screen stereotypes - does money make you mean?

The road along the seafront in Los Angeles is lined with palm trees - skateboarders and dog-walkers stroll along, heading for the beach. And social psychologist Prof Paul Piff is spending the afternoon going back and forth over a pedestrian crossing.

Thanks to the high number of wealthy locals, there is no shortage of upmarket vehicles gliding past. The four-wheel drives, sleek sports cars and nifty hybrids are an essential part of his demonstration.

He's here to illustrate one of his more provocative experiments - who is more likely to stop for pedestrians, the rich or the poor?

Drivers are legally obliged to stop if someone wishes to cross. And, as a Lexus blithely slips through in front of him, Piff explains what his researchers found.

"None of the drivers of the least expensive cars broke the law, while close to 50% of our most expensive car drivers broke the law," he says.

Media playback is unsupported on your device Media caption The pedestrian crossing experiment

Piff also asked a range of people from different backgrounds how they would behave in various scenarios.

In the past, public perception has tended towards the notion that the very poor are more likely to break the rules because they are under financial pressure and face more difficult circumstances.

But Piff's work suggests the opposite - that having more money makes you care about others less and feel entitled to put your own interests first.

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After nearly a decade researching this field, Piff has come to the controversial conclusion that being wealthy, rather than transforming you into a benevolent benefactor, can actually be rather bad for your moral fibre.

"It makes you more attuned to your own interests, your own desires, your own welfare," he says.

"It isolates you in certain ways from other people psychologically and materially. You prioritise your own needs and your own goals and become less attuned to those around you.

"If I put a pen in your hand and ask you to draw a circle to represent yourself, the wealthier you are, the larger that circle is relative to the size of the circles poorer people draw of themselves."

In his psychology lab, Piff has run studies which suggest people with more money are more likely to cheat in a dice game, more likely to take sweets reserved for children and less willing to give up their time to help others.

Using a well-known tool of psychologists, the dictator test, he took a group of people and gave some of them $10 (£7) each. He told them they could share all, some or none of that windfall with another participant who had been given nothing.

"Rational economics would say the poorer person should keep more for themselves, the richer person should give more away.

"We find the opposite. The wealthier you are, controlling for a whole slew of other variables, the less generous you are. You give significantly smaller portions away to this other person.

"Poorer people were significantly more generous - they give 150% as much as do richer participants," he says.

In another study he rigged a game of Monopoly to privilege one player, giving him or her more money to start with. As a final touch, they had the counter of the Rolls Royce to move around the board - the disadvantaged player who was destined to lose had the old boot.

After dozens of games it transpired that winning brings out the worst in the player who is scooping the board - an imperious manner, domination of the space, even eating more from a communal bowl of pretzels.

Media playback is unsupported on your device Media caption The Monopoly test

When we feel wealthy, Piff concludes, we need other people less. In the real world, when people have less money, they rely more heavily on their social relationships to get by. Therefore interpersonal relations are prioritised. The rich, by contrast, can buy themselves peace, quiet and space - plus a solution to most problems. There's nothing like a fat wallet to cheer you up in a crisis. But that tends to isolate them from others' experiences.

Piff's findings certainly have popular appeal. There's a comfort in thinking that those who enjoy the advantages of wealth might also be paying a price. But not everyone is convinced.

Psychology is a discipline fraught with difficulties. In real-world studies there are always confounding factors - does the person crossing the road step out more confidently in front of a cheaper car? Is the driver really wealthy or has he borrowed his uncle's BMW? Data from population surveys is hard to decipher. There's no way to tease apart cause and effect, and subjects who turn up to take part in lab studies give responses that may or may not bear any relation to real life.

It's only when studies employing different methods repeatedly point in the same direction that the results are deemed significant.

Since Piff published his first batch of findings in 2010, other scientists around the world have been busy trying to replicate them. Some have found results which back up Piff's work, but others, confusingly have found the opposite.

One study in the Netherlands which used real-life millionaires as its participants found they were more generous than the average person when given a small sum of money to keep or share.

Analyses of population data by academics in Europe failed to find any link between wealth and a lack of generosity. If anything, they found the reverse, that wealthier individuals were more likely to offer time and money to others.

Image caption You've now been primed. Be nice.

There is however a closely related field of study that may help explain Piff's findings.

Research by Prof Kathleen Vohs at Minnesota University might help to explain Piff's findings though. She spent her time "accidentally" dropping a bundle of little yellow pencils to see whether people would help pick them up.

First, though, she primed half of them with thoughts of money, either giving them money-related sentences to unscramble or banknotes to count.

Money-primed participants proved to be less helpful in gathering up the pencils. And in a similar study they were also less generous when invited to donate to charity.

Unlike Piff's work, this seems to have little to do with how rich or poor they are. And the results have been replicated to date in 19 countries.

"It seems there's something about the idea of money and the way that it's represented in people's minds that's causing the effects that we see and it seems like it has very little to do with whether they are feeling strapped or flush with cash," says Vohs.

Vohs says even just thinking about money invokes a "self-sufficient mindset" reflecting the fact money is all about transactions with strangers and calculating your best interest. You don't typically use money with your nearest and dearest. As a result money can make us more determined and focused but it also makes us less sensitive to the needs and feelings of others.

Image caption Prof Zhansheng Chen (l) and Prof Yuwei Jiang (r)

Researchers in Hong Kong have taken this a step further. Prof Zhansheng Chen and Prof Yuwei Jiang found money-primed subjects, when given a series of ethical dilemmas, were more likely to accept moral transgressions such as cheating in exams or lying on a CV.

And when playing a game involving punishing another participant with a blast of sound, money-primed participants set the unpleasant buzz for their unseen opponent at a consistently louder level for longer. Money priming made them more aggressive.

So focusing on prices and profits, bank accounts and budgets, may not be good for the atmosphere in your office or the integrity of your organisation.

If you want your workers to cooperate with each other and remain honest don't bribe them with bonuses, says Jiang. He has a better suggestion.

"You can award your employee a trip to Hawaii. People do not think about money when they go to Hawaii."

Listen to Discovery: Can money make you mean? on BBC World Service on Monday 16 March at 19:30 GMT or catch up via iPlayer

For more on the BBC's A Richer World go to www.bbc.com/richerworld - or join the discussion on Twitter #BBCRicherWorld