–New research shows that the visual centers of men’s and women’s brains are different, with men having greater sensitivity to fine detail and rapidly moving stimuli, while women are better at distinguishing between colors.
For the study, researchers from Brooklyn and Hunter Colleges of the City University of New York recruited a number of men and women over the age of 16 — both college students and staff — who all had normal color vision and 20/20 sight (or 20/20 when corrected by glasses or contact lenses). –
When the volunteers were asked to describe colors shown to them across the visual spectrum, it became obvious that the color vision of men was shifted. Men required a slightly longer wavelength to experience the same hue as the women, according to the researchers.
Males also had a bigger range in the center of the spectrum where they were less able to discriminate between colors.
The researchers then used an image of light and dark bars to measure contrast-sensitivity functions of vision. The bars were either horizontal or vertical and volunteers had to choose which one they saw. In each image, when the light and dark bars were alternated, the image appeared to flicker.
By varying how rapidly the bars alternated or how close together they were, the researchers found that at moderate rates of image change, observers lost sensitivity for close together bars, and gained sensitivity when the bars were farther apart.
However when the image change was faster, both sexes were less able to resolve the images over all bar widths.
The researchers also noted that, overall, the men were better able to resolve more rapidly changing images that were closer together than the women.
“As with other senses, such as hearing and the olfactory system, there are marked sex differences in vision between men and women,” said Israel Abramov, Ph.D., who led the study.
“The elements of vision we measured are determined by inputs from specific sets of thalamic neurons into the primary visual cortex. We suggest that, since these neurons are guided by the cortex during embryogenesis, that testosterone plays a major role, somehow leading to different connectivity between males and females. The evolutionary driving force between these differences is less clear.”
The research, published in BioMed Central’s open access journal Biology of Sex Differences, notes that there are high concentrations of male sex hormone (androgen) receptors throughout the brain’s cerebral cortex, especially in the visual cortex. The visual cortex is the place within the brain that is responsible for processing images.
Androgens are also responsible for controlling the development of neurons in the visual cortex during embryogenesis, meaning that males have 25 percent more of these neurons than females.
Source: BioMed Central