(620 kB) AC Little, LM DeBruine & BC Jones (2005). Sex-contingent aftereffects suggest distinct neural populations code male and female faces. Scottish Neuroscience Group Conference in Aberdeen, Scotland, UK. August 2005.

Background: Exposure to faces biases perceptions of subsequently viewed faces such that faces similar to those seen previously are judged more normal and attractive than they were prior to exposure. These aftereffects reflect changes in responses of neural populations that code faces and cannot be explained by retinal (i.e. low level) adaptation. Because it is not known if different neural populations code male and female faces, we tested for sex-contingent aftereffects following adaptation to manipulated eye-spacing (Expt 1), facial identity (Expt 2) and masculinity (Expt 3).
Summary of results: Viewing faces of one sex with increased eye-spacing and faces of the other sex with decreased eye-spacing simultaneously induced opposite aftereffects for male and female faces (assessed by normality judgments). Viewing faces transformed in identity or masculinity increased preferences for novel faces with characteristics similar to those viewed only when the sex of the faces presented in the post-adaptation preference tests was congruent with the sex of faces presented in the adaptation phase.
Conclusions: Because aftereffects reflect changes in responses of neural populations that code faces, our findings indicate that distinct neural populations code male and female faces.This raises the possibility that distinct neural populations may also code other salient subcategories of faces (e.g. faces of different ages or ethnicity). Furthermore, selective adaptation of neural populations that code for male and female faces reveals a plausible neural mechanism underlying sex-specific individual differences in generalised face preferences.

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