Melbourne School of Psychological Sciences - Research Publications

Permanent URI for this collection

Search Results

Now showing 1 - 10 of 32
  • Item
    Thumbnail Image
    Women in their mid-follicular phase outcompete hormonal contraceptive users, an effect partially explained by relatively greater progesterone and cortisol reactivity to competition
    V. Casto, K ; Arthur, LC ; Lynch-Wells, S ; Blake, KR (PERGAMON-ELSEVIER SCIENCE LTD, 2023-11)
    Early evidence suggests that hormonal contraceptive (HC) use alters psychological functioning and competitive behavior. Yet, there is limited data on endocrine models for explaining how HC use affects these outcomes. In this pre-registered and open-data study, we test if HC users and naturally cycling (NC) females in their low (mid-follicular) and high (mid-luteal) progesterone phase differ in competitive persistence and whether progesterone and cortisol reactivity mediate of this effect. HC users (N = 73) in the active hormone-exposure phase and NC participants in the mid-follicular (N = 69) or mid-luteal (N = 72) phase completed two behavioral measures of competitive persistence, holding up a weight for time followed by attempting to solve an unsolvable anagram. Participants also completed measures of handgrip strength and self-reported competitiveness as well as gave saliva samples before and after the tasks for hormone assay. Results showed that NC-follicular group had greater competitive persistence in the weight-holding task compared to both NC-luteal (d = 0.38) and HC use (d = 0.43) groups independent of physical strength and self-reported competitiveness covariates. Although anagram task performance showed similar trends for group differences, analyses for this task were inconclusive. Baseline progesterone did not mediate the effect of cycle phase group on competitive persistence. HC users showed relatively blunted cortisol and progesterone reactivity, and this effect partially mediated the difference in competitive persistence between HC users and the NC-follicular group. In sum, results suggest that HC use could downregulate competitive behavior at least partly by dampening cortisol-progesterone reactivity. These findings offer a new endocrine model for understanding HC use and cycle phase effects on motivational and energetic outcomes required for optimal performance in competitive contexts.
  • Item
    Thumbnail Image
    Not within spitting distance: Salivary immunoassays of estradiol have subpar validity for predicting cycle phase
    Arslan, RC ; Blake, K ; Botzet, LJ ; Bürkner, P-C ; DeBruine, L ; Fiers, T ; Grebe, N ; Hahn, A ; Jones, BC ; Marcinkowska, UM ; Mumford, SL ; Penke, L ; Roney, JR ; Schisterman, EF ; Stern, J (Elsevier, 2023-03)
    Salivary steroid immunoassays are widely used in psychoneuroendocrinological studies of menstrual cycle phase, puberty, and menopause. Though manufacturers advertise their assays as suitable, they have not been rigorously validated for these purposes. We collated data from eight menstrual cycle studies across > 1200 female participants and > 9500 time points. Seven studies collected saliva and one collected serum. All assayed estradiol and progesterone and had an independent measure of cycle phase (LH-surge, menstrual onset). In serum, cycle phase measures strongly predicted steroid concentrations. In saliva, cycle phase poorly predicted estradiol values, which showed an upward bias compared to expectations from serum. For salivary progesterone, predictability from cycle phase was mixed, low for enzyme-linked assays and moderate for tandem mass spectrometry. Imputing the population-average serum steroid changes from cycle phase may yield more valid values of hormonal changes for an independent person than directly assessing their hormone levels using salivary immunoassays.
  • Item
    Thumbnail Image
    Societies should not ignore their incel problem
    Blake, KR ; Brooks, RC (Cell Press, 2023-02)
    Involuntarily celibate men (‘incels’) commonly advocate for societal disruption, including violence toward women. Their anger can make them susceptible to radicalization, revolution, or reactionary hostility. Research efforts aimed at identifying the causes and consequences of incels’ beliefs are needed to address this growing problem.
  • Item
    Thumbnail Image
    Experimental and cross-cultural evidence that parenthood and parental care motives increase social conservatism.
    Kerry, N ; Al-Shawaf, L ; Barbato, M ; Batres, C ; Blake, KR ; Cha, Y ; Chauvin, GV ; Clifton, JDW ; Fernandez, AM ; Galbarczyk, A ; Ghossainy, ME ; Jang, D ; Jasienska, G ; Karasawa, M ; Laustsen, L ; Loria, R ; Luberti, F ; Moran, J ; Pavlović, Z ; Petersen, MB ; Smith, AR ; Žeželj, I ; Murray, DR (The Royal Society, 2022-09-14)
    Differences in attitudes on social issues such as abortion, immigration and sex are hugely divisive, and understanding their origins is among the most important tasks facing human behavioural sciences. Despite the clear psychological importance of parenthood and the motivation to provide care for children, researchers have only recently begun investigating their influence on social and political attitudes. Because socially conservative values ostensibly prioritize safety, stability and family values, we hypothesized that being more invested in parental care might make socially conservative policies more appealing. Studies 1 (preregistered; n = 376) and 2 (n = 1924) find novel evidence of conditional experimental effects of a parenthood prime, such that people who engaged strongly with a childcare manipulation showed an increase in social conservatism. Studies 3 (n = 2610, novel data from 10 countries) and 4 (n = 426 444, World Values Survey data) find evidence that both parenthood and parental care motivation are associated with increased social conservatism around the globe. Further, most of the positive association globally between age and social conservatism is accounted for by parenthood. These findings support the hypothesis that parenthood and parental care motivation increase social conservatism.
  • Item
    Thumbnail Image
    Effects of gender inequality and wealth inequality on within-sex mating competition under hypergyny
    Brooks, RC ; Blake, KR ; Fromhage, L (Elsevier BV, 2022-11-01)
    Resources are often central to the formation and persistence of human consortships, and to the evolutionary fitness consequences of those consortships. As a result, the distribution of resources within a society should influence the number and quality of mating opportunities an individual of given status/wealth experiences. In particular, in a wide variety of societies, both contemporary and historic, women have been shown to prefer mates of higher rather than lower status and wealth, a pattern known as ‘hypergyny’. Such status-dependent within-sex competition is influenced not only by the preferences individuals express but also by the distribution of resources within and between sexes. Empirical studies show that economic inequality within a sex can amplify mating competition, and that inequalities between women and men also influence behaviours related to mating competition, but the links between resource distribution and mating competition have attracted limited systematic attention. We present simulation models of hypergynous preferences and the effects on mating competition among men and among women within a heterosexual mating market. Our modelling shows that the lower mating success of poorer men and richer women (when compared with richer men and poorer women) is worsened when resource gender gaps are relatively small or when women out-earn men on average. Likewise, high economic inequality, especially among men, amplifies the competition experienced by these groups. We consider the political implications in terms of sex- and status-dependent attitudes to gender equity, wealth inequality, and hypergynous mating norms.
  • Item
    Thumbnail Image
    When fertile, women seek status via prestige but not dominance
    Blake, KR (NATL ACAD SCIENCES, 2022-11-15)
    Biological predictors of human dominance are hotly contested, with far-reaching implications for psychological sex differences and the placement of men and women in the social hierarchy. Most investigations have focused on dominance in men and testosterone, with diminished attention paid to dominance in women and other biological mechanisms. Investigating biological influences on other routes to status attainment popular among women-such as via prestige in addition to dominance-have also been neglected. Here, I examined whether status seeking via prestige and via dominance covaried with fertility probability in a citizen science project spanning 14 countries and 4 world regions. Across 4,179 observations, participants tracked their menstrual cycle characteristics, motivation for prestige and dominance, dominance contest outcomes, and three domains of self-esteem. Self-esteem is predicted by status within a group and helps individuals navigate social hierarchies. Bayesian mixed models controlling for menstruation indicated that the motivation to obtain status via prestige but not dominance peaked when conception was most likely, as did dominance contest losses and two self-esteem domains. Fertility appears to reorient female psychology toward prestige-based strategies to success, enhancing women's desire for social capital through influence and admiration but not through fear, coercion, or intimidation. These insights fundamentally advance the understanding of the biological correlates of status seeking among women. They further suggest that fertility motivates not only mating competition but gaining rank and positive regard in social hierarchies.
  • Item
    Thumbnail Image
    Hormonal contraceptives as disruptors of competitive behavior: Theoretical framing and review.
    Arthur, LC ; Casto, KV ; Blake, KR (Elsevier BV, 2022-07)
    Emerging evidence suggests that hormonal contraceptives (HCs) impact psychological outcomes through alterations in neurophysiology. In this review, we first introduce a theoretical framework for HCs as disruptors of steroid hormone modulation of socially competitive attitudes and behaviors. Then, we comprehensively examine prior research comparing HC users and non-users in outcomes related to competition for reproductive, social, and financial resources. Synthesis of 46 studies (n = 16,290) led to several key conclusions: HC users do not show the same menstrual cycle-related fluctuations in self-perceived attractiveness and some intrasexual competition seen in naturally-cycling women and, further, may show relatively reduced status- or achievement-oriented competitive motivation. However, there a lack of consistent or compelling evidence that HC users and non-users differ in competitive behavior or attitudes for mates or financial resources. These conclusions are tentative given the notable methodological limitations of the studies reviewed. Implications and recommendations for future research are discussed.
  • Item
  • Item
    Thumbnail Image
    "Spring is the best time to lose weight": Evidence that dieting is seasonal and reaches peak intensity during Spring
    Griffiths, S ; Cowley-Court, T ; Austen, E ; Russo-Batterham, D ; Blake, K (ELSEVIER, 2022-05-05)
    Does dieting intensify during Spring? Previous research suggests that body dissatisfaction is seasonal and peaks during Summer. Extending these findings to seasonal dieting, we contend that individuals' apprehensions about heightened Summertime body dissatisfaction motivate Springtime dieting. To detect seasonal dieting, we examined the seasonal frequencies of 69 dieting hashtags within a database of 564 million tweets originating from the United States and spanning eight calendar years (2012-19). In total, we detected 628,355 dieting hashtags. Of these, 30% occurred during Spring, 20% during Autumn/Fall, and 25% during each of Summer and Winter. During Spring, there were ~64,000 additional dieting hashtags compared with Autumn/Fall, and ~32,000 additional hashtags compared with Summer and Winter. Of the nine most common dieting hashtags that together accounted for 96% of the total, all nine peaked during Spring (ps < 0.0001). This Spring-centric pattern was apparent for both appearance-oriented diets (e.g., "atkins" and "weightwatchers") and ostensibly non-appearance-oriented diets (e.g., "vegan" and "glutenfree"), suggesting that non-appearance-oriented diets might nonetheless be co-opted for appearance-oriented purposes. In conclusion, we found credible evidence that dieting intensifies during Spring. Future research should examine whether eating disorders and muscle dysmorphia also intensify during Spring because dieting is intrinsic to both these conditions.
  • Item
    Thumbnail Image
    Number of Close Kin but Not Gendered Fitness Interests Shapes Sex Role Attitudes
    Blake, KR ; Wu, A ; McGovern, H ; Brooks, RC (Springer Science and Business Media LLC, 2023-03-01)