Although most of the tests showed no difference, there were some that did. For example, they found females performed better on verbal abilities while males performed better on visuospatial abilities.  One female advantage is in verbal fluency where they have been found to perform better in vocabulary, reading comprehension, speech production and essay writing.  Males have been specifically found to perform better on spatial visualization, spatial perception, and mental rotation.  Researchers had then recommended that general models such as fluid and crystallized intelligence be divided into verbal , perceptual and visuospatial domains of g, because when this model is applied then females excel at verbal and perceptual tasks while males on visuospatial tasks.  Thus evening out the sex differences on IQ tests.