Of all the visual skills possessed by humans, face recognition is arguably the most developed. Past brain imaging studies have shown that the brain's cortical network for face perception includes regions in visual cortex that process the identification of individuals as well as social cues, such as gaze direction and speech-related movements; the amygdala and insula, where facial expressions are processed; and regions in prefrontal cortex and the reward circuitry, where the assessment of facial beauty is processed. Numerous studies have shown that the neural response to faces is modulated by cognitive factors such as familiarity, attention, memory, visual imagery, and emotion. For example, recent empirical evidence indicates that emotional faces (e.g., happy, fearful, or angry faces) evoke stronger neural activation than neutral faces, presumably as a result of their biological importance. It is currently unknown, however, whether the response to faces is modulated by gender or sexual orientation.
Social communication requires the accurate analysis of the intentions of other individuals. To this end, men and women likely adopt strategies of "face reading" in order to successfully interact with potential sexual partners. Thus, it is reasonable to assume differential patterns of activation in the hetero- and homosexual brains in response to faces of the same or opposite sex. In their new work, the researchers hypothesized that hetero- and homosexual subjects would exhibit a greater response to faces they deem sexually preferable. Specifically, the researchers predicted similar responses to male and female faces in the visual cortex, where facial identity is proces