Do Women Have a Better Sense of Touch?
Reported December 31, 2009
(Ivanhoe Newswire) — People who have smaller fingers have a finer sense of touch, which may explain why women tend to have better tactile acuity than men.
“Neuroscientists have long known that some people have a better sense of touch than others, but the reasons for this difference have been mysterious,” study author Daniel Goldreich, PhD, of McMaster University in Ontario, was quoted as saying. “Our discovery reveals that one important factor in the sense of touch is finger size.”
To learn how finger sensitivity varies, the authors measured index fingertip size in 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. 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,” Ethan Lerner, MD, Ph.D., of Massachusetts General Hospital, was quoted as saying. “So, a man with fingertips that are smaller than a woman’s will be more sensitive to touch than the woman.”
Tinier digits likely have more closely spaced sensory receptors, the authors concluded. Several types of sensory receptors line the skin’s interior and each detects 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 on a screen, each skin receptor sends an aspect of the tactile image to the brain — more receptors per inch supply a clearer image. 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.
“Previous studies from other laboratories suggested that individuals of the same age have about the same number of vibration receptors in their fingertips. Smaller fingers would then have more closely spaced vibration receptors,” Goldreich said. “Our results suggest that this same relationship between finger size and receptor spacing occurs for the Merkel cells.”
SOURCE: The Journal of Neuroscience, December 16, 2009
