Sex hormones predict the sensory strength and vividness of mental imagery.

Mystery surrounds the cause of large individual differences in mental imagery vividness and strength, and how these might map onto mental disorders. Here, we report the concentration of sex hormones predicts the strength and vividness of visual mental imagery. We employed an objective measure of imagery utilizing binocular rivalry and a subjective questionnaire to assess imagery. The strength and vividness of imagery was greater for females in the mid luteal phase than both females in the late follicular phase and males. Further, imagery strength and vividness were significantly correlated with salivary progesterone concentration. For the same participants, performance on visual and verbal working memory tasks was not predicted by progesterone concentration. These results suggest sex hormones might influence visual imagery, but not general working memory. As hormone concentration changes over time, this implies a partial dynamic basis for individual differences in visual mental imagery, any dependent cognition and mental disorders.