Washington, March 8 (IANS) Popular notion may hold that happiness begets trust but a new study suggests that, in some instances, people may actually be less trusting of others when they are in a pleasant mood.

"A person's mood may determine how much they rely on subtle - or not so subtle -- cues when evaluating whether to trust someone," said Robert Lount, study author from Ohio State University (OSU).

In five separate experiments, Lount found that people in a positive mood were more likely than those in a neutral mood to follow cues or stereotypes when determining whether they should trust someone.

If you are predisposed to trust a stranger - because he belongs to the same club as you, or he has a "trustworthy" face -- a happy mood makes you even more likely to trust him.

But if you are predisposed not trust him, a positive mood will make you even less trusting than normal.

"I think the assumption is that if you make someone happy, they are going to be more likely to trust you. But that only works if they are already predisposed to trust you," Lount said.

"If you're a professional meeting new clients, you may think if you buy them a nice lunch and make them happy, you're building trust. But that can actually backfire if the client has some reason to be suspicious of you," he said.

All five experiments involved undergraduate students who took part in various scenarios in which they were put into positive or neutral moods, and were then given the opportunity to show trust or distrust toward a stranger.

The results were striking: participants in a positive mood evaluated the person with the trustworthy features as more trustworthy than did those in a neutral mood, said an OSU release.

Conversely, happy people were less trusting of the person with untrustworthy features than were those in the neutral mood.

The study appeared in the March issue of the Journal of Personality and Social Psychology.