That muttered curse word that reflexively comes out when you stub your toe could actually make it easier to bear the throbbing pain, a new study suggests.

Swearing is a common response to pain, but no previous research has connected the uttering of an expletive to the actual physical experience of pain.

"Swearing has been around for centuries and is an almost universal human linguistic phenomenon," said Richard Stephens of Keele University in England and one of the authors of the new study. "It taps into emotional brain centers and appears to arise in the right brain, whereas most language production occurs in the left cerebral hemisphere of the brain."

Stephens and his fellow Keele researchers John Atkins and Andrew Kingston sought to test how swearing would affect an individual's tolerance to pain. Because swearing often has an exaggerating effect that can overstate the severity of pain, the team thought that swearing would lessen a person's tolerance.

As it turned out, the opposite seems to be true.

The researchers enlisted 64 undergraduate volunteers and had them submerge their hand in a tub of ice water for as long as possible while repeating a swear word of their choice. The experiment was then repeated with the volunteer repeating a more common word that they would use to describe a table.

Contrary to what the researcher expected, the volunteers kept their hands submerged longer while repeating the swear word.

The researchers think that the increase in pain tolerance occurs because swearing triggers the body's natural "fight-or-flight" response. Stephens and his colleagues suggest that swearing may increase aggression (seen in accelerated heart rates), which downplays weakness to appear stronger or more macho.

"Our research shows one potential reason why swearing developed and why it persists," Stephens said.

The results of the study are detailed in the Aug. 5 issue of the journal NeuroReport.