Finer Sense of Touch

Women seem to be gifted with a finer sense of touch, thanks to their slender, smaller fingers.

"Neuroscientists have long known that some people have a better sense of touch than others, but the reasons for this difference have been mysterious," said neuroscientist and study author Daniel Goldreich of McMaster University.

"Our discovery reveals that one important factor in the sense of touch is finger size," added Goldreich.

To learn why men and women have different finger sensitivity, the authors first measured index fingertip size of 100 university students.

Each student's tactile acuity was then tested by pressing progressively narrower parallel grooves against a stationary fingertip - the tactile equivalent of the optometrist's eye chart.

The authors found that people with smaller fingers could discern tighter grooves.

"The difference between the sexes appears to be entirely due to the relative size of the person's fingertips," said Ethan Lerner of Massachusetts General Hospital, who is not with the study group.

"So, a man with fingertips that are smaller than a woman's will be more sensitive to touch than the woman."

The authors also explored why more slender fingers are more acute. Tinier digits likely have more closely spaced sensory receptors, they concluded.

Several types of sensory receptors line the skin's interior and each detect a specific kind of outside stimulation.

Some receptors, named Merkel cells, respond to static indentations (like pressing parallel grooves), while others capture vibrations or movement.

Much like pixels in a photograph, each skin receptor sends an aspect of the tactile image to the brain -- more receptors per inch supply a clearer image.

To find out whether receptors are more densely packed in smaller fingers, the authors measured the distance between sweat pores in some of the students, because Merkel cells cluster around the bases of sweat pores.

People with smaller fingers had greater sweat pore density, which means their receptors are probably more closely spaced, said a McMaster's release.

These findings were published in the December issue of The Journal of Neuroscience.