The hypothesis is that men and women are fundamentally different, that women are, for example, naturally more empathetic or emotionally focused. In particular, the belief it challenges is that sex differences can be easily explained by "natural" sex differences in the brain. One example she lambasts involves researchers examining brain activity while men and women performed an emotion matching test and then viewing the results as concrete support for the idea that men are naturally more rational and women more emotional2. Brain activity during these tests was at least partially present in different brain regions depending on the sex of the participant, but using these minor differences to reverse infer a psychological state from activity brain is fundamentally flawed.3 Less activation in one area may actually mean that connections have become more "streamlined" as expertise has increased and that activation of different brain regions is also highly contextual.