Method

Participants

A total of 141 heterosexual women took part in both phases (pre- and post-priming) of the online study (M age = 60.14 years, SD= 11.97 years), thus providing complete data for analysis. Given the unexpected skew in age, and before analyzing data from this sample, a separate sample of 106 heterosexual women were recruited and took part in both phases of this study. For this sample, inclusion criteria of 18–30 years of age were set via the platform’s screening tool (M age = 25.07 years, SD= 3.55 years), in order that the sample (younger sample, older sample) could be included as a factor in analyses. For both samples, American women were recruited via the buy responses function on surveymonkey.com, where participants can take part in research in exchange for the platform donating to charity.

Procedure

The study was identical to Study 3 except that we collected both a pre-priming measure of preference for heel height and a post-priming measure of preference for heel height, with identical instructions used on both occasions. In the priming phase of the study, 98 women were randomly allocated to the mating motives condition, 82 women were randomly allocated to the competitive motives condition, and 67 women were randomly allocated to our control condition.

Results

A mixed-design ANOVA on the dependent variable preference for heel height, with the within-subjects factor experimental phase (pre-priming phase, post-priming phase) and the between-subjects factors experimental priming condition (mating motive, competitive motive, control condition) and sample (older sample, younger sample), revealed no significant effects or interactions (all F < 1.39, all p > .25), except for a main effect of sample (F[1, 241] = 24.25; p < .001, np2 = .10). The same pattern of results was found when vividness of mental imagery was included as a covariate in the model.

Independent-samples t tests to interpret this main effect revealed that the younger sample preferred higher heels (M = 56.15 mm, SD= 35.28 mm) than the older sample (M = 34.09 mm, SD= 33.01 mm; t[245] = 5.05; p < .001, d = 0.65). Of note, the same pattern of results was found regardless of whether the sample was included as a between-subjects factor in the model or whether it was replaced with participant age as a covariate in an analysis of pooled data (i.e., a main effect of age was still observed).

Discussion

Our studies suggest that individual differences in women’s responses to heeled shoes can be examined using sexual selection theories. Consistent with our prediction that a high heel is a costly signal (e.g., Saad, 2013) used to augment female attractiveness (Guéguen, 2015; Morris et al., 2013; see also Lewis et al., 2017 for recent evidence) among effective competitors for mates (Vaillancourt, 2013), attractive women were more likely to choose higher-heeled shoes under time limit than their less attractive peers were. By contrast, women’s own attractiveness did not predict the proportion of lower-heeled shoes they chose under time limit, even though the two image sets were equivalent in attractiveness. Our first study suggests that when making quick choices about shoes, attractive women prefer a higher-heeled shoe. When our task was self-paced (Study 2a), attractive women had a stronger inclination to buy heeled shoes (both higher- and lower-heeled) than their less attractive peers did. This relationship remained when pooling data across two studies from separate online samples (Studies 2a and 2b). Moreover, in one study (Study 2b), relatively attractive women were more inclined to buy the attractive lower-heeled (85 mm) shoe when analyzing women’s responses to two very attractive shoes. Collectively, evidence (across both laboratory and online studies) that own attractiveness moderated women’s responses toward heeled shoes is consistent with our proposal that women augment, rather than compensate for, their physical attractiveness via heeled shoes.

We also provide the first empirical evidence, to our knowledge, that women’s responses to high-heeled shoes may be an accurate, albeit subtle, indicator of their sexual motivation. Consistent with predictions, when examining women’s responses to two very attractive heeled shoes, dyadic sexual desire (but not solitary sexual desire) predicted their inclination to buy an attractive higher-heeled shoe but did not predict their inclination to buy an attractive lower-heeled shoe. Indeed, the slopes of these two correlations differed significantly from one another. As women, in general, were equally inclined to buy these two items (a null effect of shoe in the ANOVA), the specific nature of this finding is noteworthy as it suggests that women with a stronger desire for sexual activity with a partner potentially trade off a lower heel for a higher heel when indicating their feelings toward two attractive heeled shoes. As we found no evidence, across two studies, that competitive attitudes toward other women predicted women’s responses to heeled shoes, our research suggests that wearing heels may function, in part, to aid female mate choice rather than intrasexual competition per se.

Finally, when directly examining women’s preference for heel height via a visual analogue scale (Studies 3 and 4), young women, when primed with the context that they had free choice to buy any shoe, preferred a heel in the range of 56–60 mm (Study 3: 95% CI [53.02, 67.37]). Contrary to our predictions, however, neither mating nor competitive motivations altered women’s preference toward a higher-heeled shoe when these motives were primed experimentally. Instead, women’s age had a noticeable effect on their preference for heel height, where our younger sample preferred shoes with a taller heel than our older sample did. These findings are still consistent with our general proposal that contexts where mating competition is more intense (Vaillancourt, 2013) predict preferences for a higher-heeled shoe. However, our findings suggest that between-women variation, rather than within-women variation, may be a better focus for research on differences in women’s responses to shoes, at least when we consider the contexts primed within the current studies.

Of note, although the women in our older sample preferred a lower heel, the average preference in this group still exceeded levels that can contribute to foot problems (> 25 mm, Menz & Morris, 2005). Thus, although we observed variation in heel preference according to age as predicted, women may still engage in “costly signaling” via heels at older ages, potentially for other functions. Although findings from one of our studies (Study 2b) suggest that older women were more inclined to buy heeled shoes than younger women when responding to our image set, this sample was limited to women of 18–30 years of age. As such, mating competition may be more intense within the older women in this age range, for example, in light of historical trends toward later average age at marriage (see Rotz, 2016 for American data). While this may suggest, tentatively, that the relationship between age and inclination to buy heels is curvilinear when measured across the lifespan, further work is required to examine these issues. We do note, however, that our findings for age differences in preference for heel height complement research on women’s responses to other apparel, where preferences for attractive (red) coloration in clothing are observed in young but not older women, when their hormone levels are associated with greater risk of pregnancy (Blake et al., 2017).

Future research may address potential limitations of the current set of studies. For example, it is unclear whether our findings generalize to other styles of footwear, and whether our current set of studies simply reflect women’s responses to designer footwear. Here, we were able to take advantage of access to a designer shoe label with good quality images and publicly available data on each item (including heel height). As our pilot data demonstrated strong correlations between attractiveness, sexiness, and heel height and strong (negative) correlations between heel height and traits such as “practicality” and “comfortable,” we were limited in the extent to which we could compare responses to higher heels with those of very low heels or flat shoes. However, this limitation was offset by our design where we controlled for attractiveness differences between the two image sets. This enabled us to make stronger claims about whether women “trade off” a higher versus lower heel in light of their own attractiveness, while controlling for the general appeal of the shoe (i.e., so that the motive to purchase should be equivalent across image sets, despite potential aesthetic differences unrelated to heel height).

As our sample was selective when indicating their preference toward a set of different shoes, researchers may also develop our work by examining responses to different styles of shoe at the extremes of attractiveness. For example, further work may compare women’s responses to two equally popular/attractive items within a larger image set. It may be possible to observe priming effects with the techniques used here when comparing responses to equally attractive shoes that differ in style or function, or by using other priming techniques designed to elicit sexual desire such as erotic images or audio. Diary-based studies of women’s actual choice or use of shoes (e.g., recorded via smartphone) may also provide a useful supplement to the current research. Indeed, further work such as this would be important to examine the extent to which different styles of shoe are worn for different functions, such as comfort versus attractiveness, at different times of the day.

As there is a distinction in fashion research between purchasing and consuming said items (see Morgan & Birtwistle, 2009 and O’Cass, 2000 for discussion), this may represent a limitation to our work. However, research on evolutionary perspectives to consumer behavior has examined, and provided converging evidence, for attractiveness enhancement via fashion and apparel in studies where women are asked to indicate their desire to purchase (e.g., Durante, Griskevicius, Hill, Perilloux, & Li, 2008; Hill et al., 2012) and desire to wear given items of fashion (Durante, Li, & Haselton, 2008). Indeed, evidence that women incur financial costs for a particular item is still of theoretical interest for understanding how people desire to present themselves to others on given occasions, even if the occasions in which such items are displayed are rare. Secondly, incurring costs in this way is still of practical interest to marketers as inclinations to buy items still have an influence on markets, by definition, compared to if that same preference were absent (e.g., analogous to the distinction between mate preference and mate choice). Given our pilot data revealed a strong negative correlation between a shoe’s attractiveness and how comfortable/practical it looks, our data also reveal that, on some level, judges negatively associate a shoe’s attractiveness with its practicality, at least when viewing items from a high-end retail chain.

The research reported here complements recent work, which demonstrates augmentation of physical appearance via male beards (Dixson et al., 2017, 2018) and female breasts (Dixson et al., 2015) where, for example, the attractiveness of these features is contingent on other aspects of morphology (see Dixson et al., 2015 for discussion). In arguing that heels are costly signals that augment female attractiveness, an unaddressed question from our work is the extent to which heels augment female attractiveness independent of their morphology or if the positive effects of heels on attractiveness are qualified by aspects of their facial or bodily morphology. Examining the contributions of facial and bodily morphology, motion, and expression to perceptions of women in heels versus flat shoes will likely shed light on these issues. Indeed, an alternate proposal where heels provide an indicator of confidence, as the wearer has to maintain upright gait and confident striding locomotion, is worthy of further study, although these traits may, in part, reflect perceptions of one’s own mate value. Of note, while prior work suggests that other items of cultural apparel such as makeup enhance attractiveness to a greater extent for (naturally) less attractive women than they do for naturally attractive women (Jones & Kramer, 2016), revealing a role for cultural apparel in compensating appearance, our findings suggest that use of heels may function for augmentation. Extending our paradigm and those used by others to investigate social judgments (e.g., Jones & Kramer, 2016) to examine responses to various forms of clothing and apparel that enhance status and/or attractiveness would likely prove fruitful if tested in both men and women. Examining the relative contributions of different fashion items and/or cosmetics to trait judgments, the importance of augmentation and appearance enhancement, and individual differences in orientation to different items can shed light on the use of cultural apparel in shaping social interactions, which may be of interest to both academics and marketers.

It is also worth noting that our research examined ultimate-level explanations (Scott-Phillips, Dickins, & West, 2011) for women’s choice of footwear (to improve attractiveness) and as such is not arguing that motives for the purchasing decisions observed in our studies necessarily reflect a conscious strategy among women. Nonetheless, our data suggest that sexual selection theories have utility for understanding shoe preference if the behavior (i.e., purchasing and displaying shoes) has a positive effect on reproductive fitness by enhancing one’s attractiveness relative to others (see also Vaillancourt, 2013 for discussion). It would, however, also be of great value to study women’s responses to shoes at the proximate level, for example, by attempting to reduce women’s cognitive and affective responses to various items of footwear to their primary dimensions via a data-driven approach (e.g., to test for divergent and/or converging evidence, see Munafo & Smith, 2018). Examining preferences for heeled shoes across generations would also likely prove fruitful, if historical data exist on this such as data from sales or observations from work of art. Of note, although data from our first study revealed no effect of self-reported height on women’s shoe choices, further work, which takes a data-driven and/or theory-driven approach, could examine the role of height and/or body size more generally in women’s shoe choices, particularly as size alters the costs versus benefits of wearing heeled shoes (e.g., Titchenal et al., 2015). Such research could consider women’s height/size in absolute terms and/or when compared to the height of other women within their immediate environment.

To conclude, our findings extend research on sartorial appearance by demonstrating that age, self-rated attractiveness, and dyadic sexual desire moderate women’s responses to heeled shoes. Purchasing and displaying heeled shoes may function for females to augment, rather than compensate for their attractiveness, and women may orient themselves differently toward footwear depending on their sexual motives and at times in the lifespan where mating competition is relatively intense.