A recent study showed that White British heterosexual men’s preferences for larger female breasts were significantly associated with a greater tendency to be benevolently sexist, to objectify women, and to be hostile towards women (Viren Swami and Martin J. Toveé, 2013).
Since the article isn’t open access, I will briefly summarise what they did and found, which will inevitably leave out things that are also relevant and noteworthy, but ok:

Based on self-reports, they selected a sample of 361 males of Britisch White descent, who didn’t indicate being gay or bisexual or didn’t disclose their preference (average age 30, ranging from 18 to 68). Those were asked to rate the attractability of photo-realistic 3D models that were rotated on the screen. I copied and pasted from the article the model with the smallest breast size out of five on the left, and the one with the largest on the right so you get a bit of an idea. In the study they were presented in colour. After having rated the models, the participants were asked to fill in questionnaires that measure sexist attitudes (Hostility Towards Women Scale HTWS, Attitudes Towards Women Scale AWS and Benevolent Sexism BS subscale of the Ambivalent Sexism Inventory ASI) and that measure objectification of women (an adaptation of the Self-Objectification Scale SOS).
What they found was that on average men found the medium breast size model most attractive, with a skewed distribution towards the larger breast size, which seems unsurprising. The men’s preference for larger breast sizes was significantly and positively correlated with hostility towards women, more sexist attitudes towards women, benevolent sexism and objectification of women. They also found that young men were more likely to rate large breasts as more attractive. Neither education nor relationship status had an effect. Benevolent sexism was the strongest predictor for breast size rating, while objectifaction of women and hostility towards women were also significant predictors.
Some highlights from the discussion which I thought were noteworthy:
“[…] insofar as breasts are an index of a gendered difference between women and men, benevolently sexist men may perceive larger breasts as ‘‘appropriate’’ for feminine women; in other words, in the view of benevolently sexism men, a feminine and submissive woman is likely to be someone with large breasts.”
“Based on this set of results, it might be argued that it is the tendency to view women in ways that are subjectively positive for the perceiver rather than to explicitly denigrate women that drives men’s breast size preferences. Of course, both types of sexism stem from issues relating to power, gender identity, and sexuality, and it should also be noted thatbenevolent sexism may also serve to justify hostile attitudes toward women (Glick&Fiske, 1996).”
“Our results also showed that a greater tendency to objectify women was associated with a greater likelihood of rating larger breasts as physically attractive. Previous scholars have argued that, in many socioeconomically developed societies, female breasts have become an important site of objectification of the femalebody (Seifert,2005;Wardetal.,2006). This is evidenced, for example, in media aimed at hegemonic masculinities (Gerald & Potvin, 2009), where large female breasts are fetishized and treated as sexual objects that fulfill the pleasures and desires of masculine men. In this view, the objectification of women’s body parts, including though not limited to their breasts, is an example of the dominance of men over women and is further reproduced through cultural expectations of heteronormativity (Martino & Pallotta-Chiarolli, 2005). Moreover, this normalization compels women to put up with the objectification of their breasts and bodies by men, and even to treat such objectificationas flattering (Pascoe, 2007).”
They acknowledge a number of shortcomings in the research, such as the models all having the same face and waist-to-hip ratio and such, and all the breasts being the same shape. They further indicate the rather standard issues with recruitment method of the participants that might limit the generalisability (if that’s a word) and the possibility of socially desirable responding.
“In summary, the results of the present study showed that men’s oppressive beliefs predicted their idealization of larger female breasts. These results may have important implications for contemporary theorizing of breast size preferences. In addition to considering the distal evolutionary pressures that led to men’s breast size preferences, our findings also highlight the importance of considering the proximate sociocultural context in which thosejudgments aremade (cf. Little, Jones, DeBruine, & Caldwell, 2011). Specifically, it seems clear that the lived experiences of women and men in contemporary societies, and particularly their gendered relations with one another, will have a major impact on their beauty ideals and practices (Forbes et al., 2007).More broadly, future research would do well to more carefully consider the ways in which such beauty ideals shape and maintain gendered divisions in contemporary societies.
Fascinating.