Negotiators who complimented their adversaries and who were instructed to be ''playful'' were actually losers at the bargaining table compared with those who played it straight, according to a study.

Two University of California, Berkeley business professors put together three experiments comparing flirtatious sellers to neutral sellers. The buyers were not given instructions on how to act.

Those who were told to flirt with their bargaining partner in the role-playing games were perceived as more likable. They even lifted the moods of those they flirted with. But they consistently got worse offers, and the flirty sellers' own moods suffered as a result of straining to play a role.

Men picked up on the flirtation more often and liked a flirtatious female bargaining partner even more than women liked the flirtatious men. ''It's the only domain in which men are actually more sensitive,'' said Laura Kray, one of the Berkeley professors.