Princeton University psychologist Susan Fiske took brain scans of heterosexual men while they looked at sexualised images of women wearing bikinis. She found that the part of their brains that became activated was pre-motor - areas that usually light up when people anticipate using tools. The men were reacting to the images as if the women were objects they were going to act on. Particularly shocking was the discovery that the participants who scored highest on tests of hostile sexism were those most likely to deactivate the part of the brain that considers other people’s intentions (the medial prefrontal cortex) while looking at the pictures. These men were responding to images of the women as if they were non-human.