It's official: Men and women literally see the world differently, according to new research.
While men's eyes are more sensitive to fine detail and rapidly moving objects, women pick up differences in colours, researchers from the Brooklyn and Hunter Colleges of the City University of New York have found.
The research compared the vision of 16 men and 36 women aged between 16 and 38, all with 20/20 vision, or at least 20/20 when wearing glasses.
Participants were asked to describe different colours shown to them. Men required a longer wavelength of a colour to see the same shade as women, and men were also less able to discriminate the differences between hues.
An image of light and dark bars was then used 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 were unable to see the bars when they were close together but gained sensitivity when the bars were farther apart.
When the image change was faster, both sexes were less able to resolve the images over all bar widths, however overall the men were better able to resolve more rapidly changing images that were closer together than the women.
The findings have been published in the journal Biology or Sex Differences.
Previous research has found that women have more sensitive noses and ears to men.
"As with other senses, such as hearing and the olfactory system, there are marked sex differences in vision between men and women," lead researcher Israel Abramov concluded in a statement.
"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 researchers said the differences may be adaptive.
"The sex-differences in vision might relate to different roles of males and females of early hunter-gatherers; males, being generally larger and more powerful, would have to detect possible predators or prey from afar and also identify and categorize these objects more easily," the research concluded. "It is noteworthy that sensitivities to low spatial frequencies is enhanced by temporal modulation; in the real world, retinal images are rarely stationary - objects move and the observer moves."