Hormones and Persistence
In recent years, the use of hormonal contraceptives (HC) have been extended to other menstrual problems, apart from just its predominant use for pregnancy prevention (Prior, 2016). HCs vary on the mode and route of delivery as well as other factors such as dosage, hormone type, hormone free days, etc., but the most common is the oral contraceptive which contains a mixture of synthetic oestrogens (Hall & Trussell, 2012). Endogenous estradiol and progesterone HCs affect sexual development, fertility, basic neural functioning, emotion, cognition and social and sexual behaviour (Jones et al., 2019). Initial studies have indicated that users of HC have low task performance, lower competitive behaviour and are less likely to self-select into a competitive tournament as compared to non-users (Buser, 2012). Most HCs also consist of synthetic progesterone, which is believed to mediate neurological changes. The anti-androgenic abilities of some progestins are known to inhibit the promotion of competitive behaviour, indicating a role for the specific progestin formula in the behavioural effects of HCs (Pletzer et al., 2015). High progesterone levels during the mid-luteal phase increase motivation for social interactions, but reduces competitive interactions (Gangestad & Grebe, 2017). The ovulatory period marked by a peak in estradiol is known to correlate with intrasexual competitive behaviour in other areas including and beyond the acquisition of high-quality mates (Blake et al., 2016). However, whether competitive behaviour differs between early- to mid-follicular phase—where progesterone is quiescent—and mid-luteal phase—where progesterone is dominant—has not been well-studied (Roney & Simmons, 2016).
Research Questions / Hypotheses
Research Questions: 1. Is there a difference in competitive persistence between naturally cycling women in their mid-luteal phase compared to their mid-follicular phase? 2. Does progesterone have a role in explaining the effect of menstrual-cycle phase on competitive persistence? Hypotheses: 1. Naturally cycling women in their mid-follicular phase (NC-MF) will demonstrate higher competitive persistence than women using hormonal contraceptives (HC users) and naturally cycling women in their mid-luteal phase (NC-ML). 2. Among naturally cycling women, progesterone levels will mediate the relationship between cycle phase and competitive persistence, with higher progesterone predicting lower competitive persistence.
83 REP participants completed the study and 4 were excused no-shows.
Participants complete a one-minute online pre-screening form, which automatically determines their eligibility for the study based on their age, menstrual cycle characteristics, HC usage, and relevant medical history. Eligible participants are then scheduled to attend a laboratory session at a particular point in their menstrual cycle. They receive a reminder email prior to their session to remind them of the session requirements and to complete a health declaration. At the laboratory session, participants complete: *a Competitiveness Orientation questionnaire *a test of hand-grip strength using a standard digital hand dynamometer *a Competitive Will Task (Participants hold a .5kg dumbbell at arm’s length and shoulder height for as long as they feel they can in competition against previous participants) *an Anagram completion task *other questionnaires measuring covariates, including height and weight *two saliva samples The study then ends.
Data will be analysed using a one-way ANOVA and regression mediation model, allowing us to test group differences (HBC v NC) and mediators (progesterone) on competitiveness. We expect the results to follow the patterns predicted in our hypotheses above.
The effects of the cyclic changes in women’s hormonal levels, and their consequent effects on their behaviour between HC users and non-users is a topic area of great contention. To better understand whether progesterone reduces competitive motivation, a detailed examination of differences in competitiveness between mid-follicular and mid-luteal phases, and the hormonal mechanisms underpinning any resulting effects, is warranted. Should HCs, or natural shifts in progesterone, produce a systematic difference in competitive motivation, this is an important contribution to the literature on female behaviour.