Friday, October 16, 2020

Voice Pitch Seems A Valid Indicator of One’s Unfaithfulness in Committed Relationships

Voice Pitch – A Valid Indicator of One’s Unfaithfulness in Committed Relationships? Christoph Schild, Julia Stern, Lars Penke & Ingo Zettler. Adaptive Human Behavior and Physiology, Oct 16 2020.


Objectives: When judging a male speakers’ likelihood to act sexually unfaithful in a committed relationship, listeners rely on the speakers’ voice pitch such that lower voice pitch is perceived as indicating being more unfaithful. In line with this finding, a recent study (Schild et al. Behavioral Ecology, 2020) provided first evidence that voice pitch might indeed be a valid cue to sexual infidelity in men. In this study, male speakers with lower voice pitch, as indicated by lower mean fundamental frequency (mean F0), were actually more likely to report having been sexually unfaithful in the past. Although these results fit the literature on vocal perceptions in contexts of sexual selection, the study was, as stated by the authors, underpowered. Further, the study solely focused on male speakers, which leaves it open whether these findings are also transferable to female speakers.

Methods: We reanalyzed three datasets (Asendorpf et al. European Journal of Personality, 25, 16–30, 2011; Penke and Asendorpf Journal of Personality and Social Psychology, 95, 1113–1135, 2008; Stern et al. 2020) that include voice recordings and infidelity data of overall 865 individuals (63,36% female) in order to test the replicability of and further extend past research.

Results: A significant negative link between mean F0 and self-reported infidelity was found in only one out of two datasets for men and only one out of three datasets for women. Two meta-analyses (accounting for the sample sizes and including data of Schild et al. 2020), however, suggest that lower mean F0 might be a valid indicator of higher probability of self-reported infidelity in both men and women.

Conclusions: In line with prior research, higher masculinity, as indicated by lower mean F0, seems to be linked to self-reported infidelity in both men and women. However, given methodological shortcomings, future studies should set out to further delve into these findings.


In this Registered Report, we reanalyzed three datasets to test a potential relation between F0 and self-reported infidelity in n = 319 male and n = 551 female speakers. While a significant negative link between mean F0 and self-reported infidelity was found in only one out of two datasets for men and only one out of three datasets for women, two meta-analyses (accounting for the sample sizes and including the original Schild et al. 2020, data for men) suggest that lower mean F0 might be a valid indicator of higher probability of self-reported infidelity in both men and women. The one dataset that yielded significant associations for both men and women and had vocal attractiveness ratings suggests that this effect was not mediated by vocal attractiveness in men, but partially mediated by vocal attractiveness in women, such that lower mean F0 predicted lower vocal attractiveness, which in turn predicted a higher likelihood of self-reported infidelity. Further, where it was possible to test, relationship length was associated with higher self-reported infidelity such that participants were more likely to report extra-pair copulations in longer relationships. This is in line with the finding that sociosexual desire tends to become more unrestricted and sexual interests broaden to people outside of committed relationships after about 4 years of relationship duration, sometimes called the “4 year itch” (Fisher 1987; Penke and Asendorpf 2008). However, the effect of mean F0 on infidelity is independent of relationship length. Participants’ age seemed to be unrelated to their self-reported infidelity.

Why is F0 Associated With Unfaithfulness in Committed Relationships?

Whereas previous studies report that male speakers with lower pitched voices are perceived as more likely to act sexually unfaithful in a committed relationship than speakers with higher pitched voices (O’Connor et al. 2011; O’Connor and Barclay 2017), only one previous study investigated whether mean F0 is actually linked to a higher likelihood of self-reported infidelity (Schild et al. 2020). In an exploratory finding, Schild and colleagues (Schild et al. 2020) report that men with lower F0 were, indeed, more likely to cheat in committed relationships. Further, the relation between F0 and sexual infidelity in women has not been tested so far. The current study presents evidence that F0 is actually linked to sexual unfaithfulness in men and women. Although the evidence is rather mixed in all of the separately analyzed datasets, the conducted meta-analyses suggest that men and women with lower F0 more often report to cheat in committed relationships. However, in line with the mixed findings, we recommend future research to investigate the robustness of our findings.

That mean F0 might be a valid cue to one’s sexual infidelity could also explain why listeners were found to make accurate judgements about the sexual infidelity of speakers in two prior studies (Hughes and Harrison 2017; Schild et al. 2020). Picking up on a valid cue to potential infidelity might be especially relevant to avoid high fitness costs such as the loss of protection and provisioning (Geary et al. 2004) as well as parental and relationship investment (O’Connor et al. 2011). However, while no other vocal parameters in this study were found to be valid indicators of self-reported infidelity, future research should set out to investigate whether other aspects of vocal communication, such as clarity of speech (Kempe et al. 2013), are valid cues to one’s infidelity.

Our findings are in line with previous findings indicating that men with lower mean F0 also report higher mating success (e.g., Puts 2005) and a higher number of sexual partners (e.g., Hughes et al. 2004), which is indicative of a less restricted sociosexual orientation. In turn, an unrestricted sociosexual orientation is linked to less commitment to romantic relationships and higher likelihoods of infidelity (Mattingly et al. 2011; Penke and Asendorpf 2008). But why is F0 associated with a higher likelihood of infidelity? Romantic infidelity can be the result of situational (e.g. opportunities) and dispositional factors (Blow and Hartnett 2005; Hilbig et al. 2015). With regard to opportunities for infidelity, lower mean F0 in men is associated with both perceptions of attractiveness and dominance (e.g., Puts et al. 2016), so it increases success in both being chosen by the opposite sex and intrasexual competition. The association can thus not distinguish between these two routes to infidelity opportunities, though two studies suggest that success in male-male competition, rather than female mate choice, is a more important predictor of male number of sexual partners and that male F0 is under stronger intrasexual than intersexual selection (Hill et al. 2013; Kordsmeyer et al. 2018). In contrast, lower female mean F0 is perceived as more dominant but less attractive (e.g., Borkowska and Pawlowski 2011; Jones et al. 2010). Interestingly lower, not higher, mean F0 predicted infidelity in women. This could either mean that being perceived as dominant is important for female infidelity opportunities, just as it is for men. Alternatively, it could be interpreted as less vocally attractive women being more likely to be romantically unfaithful, which is corroborated by the partial mediation of the F0-infidelity association by lower rated vocal attractiveness in Dataset 2. Vocal attractiveness contributes to women’s likelihood of being chosen by potential mates over and beyond physical attractiveness (Asendorpf et al. 2011). Thus, it might be that less vocally attractive women end up with less opportunity to engage in a committed relationship with a preferred partner on a competitive mating market with mutual mate choice, as is typical for modern humans (Penke et al. 2008). If this is the case, these women might use infidelity as a mate switching strategy (Buss et al. 2017). As another alternative, a lower F0 and the disposition for infidelity might share a common cause in both men and women. A candidate would be androgenic masculinization throughout development. Both, mean F0 (Puts et al. 2012ab) and unrestricted sociosexual desire (Penke and Asendorpf 2008; Schmitt 2005), as well as the closely related desire for sexual variety (Schmitt and International Sexuality Description Project 2003), are strongly sexually dimorphic in humans. Importantly, higher masculinity is also linked to less restricted sociosexual orientation (Ostovich and Sabini 2004) and more sexual partners across the lifespan (Burri et al. 2015) in women, potentially explaining our findings. Lastly, given that women lower their mean F0 when talking to more attractive men (Hughes et al. 2010), when speaking to men they prefer (Pisanski et al. 2018) and when trying to sound sexy or attractive (Hughes et al. 2014), it might be that lower mean F0 indicates general interest and attracts more opportunities for infidelity. Importantly, all these potential explanations are not mutually exclusive, and might thus be addressed explicitly by future research.


Our investigation has four potential limitations in particular. First, due to the item wording, our infidelity measure was only a proxy of self-reported infidelity in Datasets 1 and 2: While one can assume that a majority of extra-pair copulations are, indeed, best described by acts of infidelity, other extra-pair copulations might actually be accepted by the partner (e.g., in polyamorous couples or open relationships, which were not assessed). Thus, our outcome measure might contain noise. However, note that only around 5% of relationships in western countries (such as those in which our data were collected) are consensually non-monogamous (Rubin et al. 2014). Second, as in Schild et al. (2020), we were only able to analyze whether individuals have ever cheated on any of their partners. We are not able to investigate or draw any conclusions about (a) how many of their partners they have cheated on (just one, all of them, or anything in between), (b) what were the reasons for cheating, and (c) whether cheating that does not involve sexual intercourse (e.g., kissing) is also related to F0. Third, for assessing infidelity, we relied on self-report measures. However, as infidelity in committed relationships is rather socially undesirable (Mogilski et al. 2014), there is a chance that not all participants gave honest responses to these questions, although all surveys were administered completely anonymous. Fourth, although the overall sample size of this investigation was relatively large, the asymmetric distribution of cheaters and non-cheaters decreased the statistical power of this investigation. In detail, 39%, 37%, and 17% of the study participants reported infidelity in Dataset 1, Dataset 2, and Dataset 3, respectively. We strongly encourage future studies to replicate our study and resolve potential problems that limit the interpretability of the current study’s findings.

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