Fifteen minutes later, the men gave another saliva sample. Then they were asked to taste a lidded 3-ounce cup of water with a drop of Frank's Red Hot Sauce in it.

For half the men, the object was a pellet gun that mimicked a Desert Eagle automatic handgun. The other half of the men worked with a child's game called Mouse Trap.

Klinesmith told the men they'd be taking part in a study of the effect of attention to detail on taste sensitivity. She collected a saliva sample for testosterone testing. Then she led each man into a room where he sat at a table with an object on it. The man had to take apart the object and put it back together according to instructions.

The finding comes from a study by psychology student Jennifer Klinesmith and her professors at Knox College, Galesburg, Ill. Klinesmith designed the study, in which 18- to 22-year-old college men participated.

Hot-Sauce Trick

Finally, the men were given a 3-ounce cup of water and a bottle of the hot sauce. They were told the water would be given to the next man in the study, and that they could -- anonymously -- put as much hot sauce in the water as they liked.

This hot-sauce trick has been used before. The more aggressive a man is feeling, the more hot sauce he tends to put in the next guy's drink.

Sure enough, testosterone went up about 100 times more in the men who handled the gun than in the men who handled the children's toy. And the gun handlers put three times more hot sauce in the water -- on average, about a half ounce -- than the toy handlers.

The more a man's testosterone went up after gun handling, the more hot sauce he put in the water.

"Such findings raise many of the usual questions about whether the presence of guns in modern society contributes to violent behavior," Klinesmith and colleagues conclude. "Although our study is clearly far from definitive, its results suggest that guns may indeed increase aggressiveness partially via changes in the hormone testosterone."

Indeed, after debriefing, many of the men said they were disappointed that the water they'd spiked with hot sauce wasn't really going to be given to another unsuspecting man.

The study appears in the July issue of Psychological Science.