Some suffered damage to brain

She made the remark on the Stanford Graduate School of Business Web site. The study was carried out by Stanford, Carnegie Mellon University and the University of Iowa.

The 41 participants in the study were given $20 to play a gambling game.

At the beginning of every round, they had to decide whether to risk a $1 stake on a toss of the coin, for a $2.50 return if they won. While any player could decline to take part in a round, the financially “logical” approach to the game was to participate at each stage because the “potential return” outweighed the risk of loss, according to the research.

Fifteen of the players had suffered damage to the areas of the brain that affect emotions. They finished on average $3 richer than the others and invested in 84% of the rounds, compared with 58% played by the rest, who let “fear” govern their decisions, the study showed.

The researchers used “control” players, who had brain lesions in areas that aren’t involved with emotions, to aid the study’s precision. Those patients behaved similarly to the “ normal” participants.

The results help to explain the “equity premium puzzle,” or why more people invest in bonds than stocks, when equities historically offer a higher average return, the report said.

“Investors are not behaving in their own best financial interest,” co-author Baba Shiv of the Stanford Graduate School of Business said. “ All research suggests that, even after taking into account fluctuations in the market, overall people are better off investing in stocks in the long term.”

Many successful investors may be so-called “functional psychopaths” because they lack or can suppress emotions, according to the study.

Still, Mr. Shiv said emotions aren’t all bad.

Those who can’t experience feelings tend to make “ disadvantageous” social decisions, losing their jobs and their friends, the report said.

The study was published in the journal Psychological Science in June, according to the statement on the Web site.