Want a better deal when negotiating the price of a car or house? Make sellers believe you are upset with them over their initial offer, suggests new research into consumer behaviour.

Marketing experts with the University of California at Berkeley call the behaviour "emotion gaming," and say their study shows not only is it a powerful negotiating technique, but many of us have no qualms in using it.

The study was published online in last month's Journal of Consumer Research.

The researchers studied the behaviour of 30 university students in a series of experiments in which they were divided into pairs and asked to play two different games.

In the first game, called the dictator game, one participant was given $10 and asked to divide the money between themselves and their partner. The partner had to accept the offer no matter what.

In all instances, the participant divvying up the money kept most of it for themselves, eliciting anger in their partners. Partners were then asked to rate their anger on a scale of 1 to 100.

In the second game, called the ultimatum game, the participant with the $10 was again asked to divide the money. Only this time, the player on the receiving end could accept or reject the offer. If they rejected it, neither partner got to keep any money.

The receivers of the money were told their rating of anger over the previous game's results would be shared with their partner. They were then given the opportunity to revise that rating. All of them inflated their anger, telling researchers they were hoping for a better deal in the second game.

"They said, 'Look, I'm inflating strategically because I want the guy to give me more money,'" said Eduardo Andrade, lead author and assistant professor of marketing.

Make partner believe anger is genuine

Andrade and his colleague, Teck-Hua Ho, discovered that the ruse did in fact work.

Participants asked to divide the money in the second game gave more to their partners when they were made aware of their partners' level of anger.

But the trick, said Andrade, is to make your negotiating partner believe your anger is genuine.

When those dividing the money were told their partners knew their anger rating would be passed on, they did not give away a greater share of the $10.

Researchers concluded that was because the player dividing the money felt their partners' anger was falsely inflated in order to secure a better deal.

"You want emotion gaming to be credible," said Andrade, who advises consumers to hide their eagerness for the object in question until after the deal is done.