Proposed by Beach in 1976. Classifying behavior may help understand the hormones underlying them. Attractivity is measured by a PROX score based on the amount of time the male spends in proximity of the female. Some factors may mediate attraction. Females exposed prenatally to androgens tend to be less attractive to males.
Males also find females attractive who engage in flirting behavior.
Estrogens also enhance attractivity which is highest around ovulation. Ovariectomy reduces the effect, as well as progesterone. Measured in terms of what behaviors the female engages in and what she'll go through to get a mate. Proceptivity can also be determined by male attractiveness. Measured through lordosis behavior.