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Logo of biosexdiffBioMed CentralBiomed Central Web Sitesearchsubmit a manuscriptregisterthis articleBiology of Sex DifferencesJournal Front Page
 
Biol Sex Differ. 2012; 3: 20.
Published online Sep 4, 2012. doi:  10.1186/2042-6410-3-20
PMCID: PMC3447704
Sex & vision I: Spatio-temporal resolution
Israel Abramov,corresponding author1,2,3,4 James Gordon,3,4,5 Olga Feldman,1 and Alla Chavarga1
1Psychology, Brooklyn College, City University of New York, Brooklyn, NY, 11210, USA
2Cognition, Brain, and Behavior, The Graduate Center, City University of New York, New York, NY, 10016, USA
3Psychology, Hunter College, City University of New York, New York, NY, 10065, USA
4Biopsychology and Behavioral Neuroscience, The Graduate Center, City University of New York, New York, NY, 10016, USA
5Center for Neural Science, New York University, New York, NY, 10003, USA
corresponding authorCorresponding author.
Israel Abramov: iabramov/at/brooklyn.cuny.edu; James Gordon: jgordon/at/hunter.cuny.edu; Olga Feldman: olya.bresler/at/gmail.com; Alla Chavarga: alla.chavarga/at/gmail.com
Received November 21, 2011; Accepted July 11, 2012.
Abstract
Background
Cerebral 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.
Methods
We 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.
Results
At 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.
Conclusion
As 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.
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