14 DAY TRIAL // Women and men indeed see things differently, a new study finds. That is to say, their visual cortices are wired differently, and have evolved to be efficient at discerning between different types of stimuli.
While the visual cortex of a man is hardwired to observe rapid-moving stimuli and very fine details, that of a women is evolved to recognize subtle differences between colors that would not elicit the attention (or interest) of a man.
Partially responsible for this is the fact that men have roughly 25 percent more neurons in their visual cortex than women do. This difference arises from the higher concentration of the male sex hormone androgen in the brain before birth.
This chemical is responsible for promoting the development of visual neurons that process images. Since men's brains are bathed in androgen and testosterone, it stands to reason that more nerve cells of this type will develop.
The investigation, carried out by scientists at the Brooklyn and Hunter Colleges of the City University of New York, is detailed in the latest issue of Biology of Sex Differences, which is an open-access journal published by BioMed Central.
Study team leader, professor Israel Abramov, says that differences between males and females exist in all of the senses, so it makes sense that visual processing is no exception, Science Blog reports.
Researchers conducted their study by asking a group of men and women, over the age of 16, to describe a series of colors they were shown on a computer screen. All participants have 20/20 vision.
What became immediately visible, so to speak, is that men had a somewhat shifted color vision, meaning that, in order for them to see the exact same hue as women, a slightly longer wavelength was required.
In the middle of the color spectrum, men had a wider area where they could not discriminate between colors than women did. In an associated experiment, the team observed that men were better able to resolve rapidly changing image movements, which makes sense from an evolutionary perspective.
“As with other senses, such as hearing and the olfactory system, there are marked sex differences in vision between men and women. The elements of vision we measured are determined by inputs from specific sets of thalamic neurons into the primary visual cortex,” Abramov explains
“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,” he concludes.