Sex & vision I: Spatio-temporal resolution

Abstract

BackgroundCerebral cortex has a very large number of testosterone receptors, which could be a basis for sex differences in sensory functions. For example, audition has clear sex differences, which are related to serum testosterone levels. Of all major sensory systems only vision has not been examined for sex differences, which is surprising because occipital lobe (primary visual projection area) may have the highest density of testosterone receptors in the cortex. We have examined a basic visual function: spatial and temporal pattern resolution and acuity.MethodsWe tested large groups of young adults with normal vision. They were screened with a battery of standard tests that examined acuity, color vision, and stereopsis. We sampled the visual system’s contrast-sensitivity function (CSF) across the entire spatio-temporal space: 6 spatial frequencies at each of 5 temporal rates. Stimuli were gratings with sinusoidal luminance profiles generated on a special-purpose computer screen; their contrast was also sinusoidally modulated in time. We measured threshold contrasts using a criterion-free (forced-choice), adaptive psychophysical method (QUEST algorithm). Also, each individual’s acuity limit was estimated by fitting his or her data with a model and extrapolating to find the spatial frequency corresponding to 100% contrast.ResultsAt a very low temporal rate, the spatial CSF was the canonical inverted-U; but for higher temporal rates, the maxima of the spatial CSFs shifted: Observers lost sensitivity at high spatial frequencies and gained sensitivity at low frequencies; also, all the maxima of the CSFs shifted by about the same amount in spatial frequency. Main effect: there was a significant (ANOVA) sex difference. Across the entire spatio-temporal domain, males were more sensitive, especially at higher spatial frequencies; similarly males had significantly better acuity at all temporal rates.ConclusionAs with other sensory systems, there are marked sex differences in vision. The CSFs we measure are largely determined by inputs from specific sets of thalamic neurons to individual neurons in primary visual cortex. This convergence from thalamus to cortex is guided by cortex during embryogenesis. We suggest that testosterone plays a major role, leading to different connectivities in males and in females. But, for whatever reasons, we find that males have significantly greater sensitivity for fine detail and for rapidly moving stimuli. One interpretation is that this is consistent with sex roles in hunter-gatherer societies.

A population study of binocular function

“…Where sex differences in contrast sensitivity897 have been reported in the literature, they tend to be in the same 898 direction as in the present study(Abramov et al, 2012; Hashemi 899 et al, 2012;Oen, Lim, & Chung, 1994).Brabyn and McGuinness 900 (1979) report an interaction between sex and spatial frequency 901 with females superior at low spatial frequencies and males at high.…”

Gender Differences in Cognitive Functioning in Older Alcohol-Dependent Patients

“…We would expect this effect to become even stronger after adjustment for duration of alcohol dependence; however, we were not able to analyze this due to selectively missing data. Several authors found that men performed better than women on a figure recognition task (Abramov, Gordon, Feldman, & Chavarga, 2012;Halpern & LaMay, 2000). However, a more recent study did not find gender-related differences in figure recognition (Lewis, Rees, & Lee, 2009).…”

Gender Based Occupational Segregation and Sex Differences in Sensory, Motor and Spatial Aptitudes

“…For example, adult males exhibit better visual acuity-sensitivity to fine detail and rapidly moving stimuli (Velle 1987, Abramov et al 2012a. A suspected cause is the high number of testosterone receptors in the cerebral cortex.…”

“…Environmental factors may also play a role, as there is evidence that vision acuity can be improved through training (Ward et al 2008; also see Halpern, 2012). Finally, evolutionary explanations have also been forwarded based on the distinct gender roles in hunter/gatherer societies (Abramov et al 2012a). …”