Infidelity: Men indicated significantly higher jealousy to sexual as opposed to emotional messages with the reverse pattern evident in women; women & men differed in jealousy when her sister & his brother were involved

Infidelity-Revealing Snapchat Messages Arouse Different Levels of Jealousy Depending on Sex, Type of Message and Identity of the Opposite Sex Rival. Michael J. Dunn, Kayleigh Ward. Evolutionary Psychological Science, August 13 2019. https://link.springer.com/article/10.1007/s40806-019-00210-3

Abstract: Research highlighting sex-differentiated jealousy resulting from imagined scenarios has now been reaffirmed when the infidelity-revealing message is discovered on a social media platform. Participants in the current study were presented with both sexually and emotionally charged infidelity-revealing scenarios featuring a same-sex sibling, a friend and a stranger in the format of a ‘Snapchat’ message. Men indicated significantly higher jealousy to sexual as opposed to emotional messages with the reverse pattern evident in women. Sex differences were also evident in the extent of jealousy elicited by ‘third-party’ identity. Women were significantly more jealous when the imagined infidelity occurred between their sister compared to both a best friend and a stranger with males showing significantly lower jealousy directed towards their brother compared to a stranger. These findings are supportive not only of a parental investment (PI) interpretation of sex differences in jealousy but also an interpretation consistent with aspects of inclusive fitness theory.

Keywords: Infidelity Snapchat Evolutionary psychology Jealousy type Sex differences Genetic relatedness

Discussion

The central thrust of the current research was to (1) establish if sex differences existing in jealousy manifestation upon the discovery of infidelity-revealing social media (Snapchat) messages are reflective of those found in the offline world and (2) to explore the extent to which feelings of jealousy elicited by imagined infidelity discovered whilst snooping on a partner’s Snapchat account differ depending on the identity of the third party. Broad support for the evolutionary psychological perspective was found as women reported more jealousy to emotional than sexual infidelity and higher emotional jealousy overall in comparison to males, whereas males reported higher jealousy to sexual as opposed to emotional partner infidelity. No differences were recorded however between men and women with regard to jealousy elicited by sexual infidelity. The identity of the ‘other-person’ was also shown to have a considerable bearing on reported jealousy and, once again, intriguing sex differences were evident. Women experienced significantly higher jealousy when the same-sex rival was a sibling than when the rival was either a best friend or a stranger. Conversely, men reported significantly lower imagined infidelity-elicited jealousy directed towards their own brother than imagined infidelity-elicited jealousy occurring between their partner and a same-sex stranger.

Firstly, the current study augments a growing body of research showing modest yet consistent sex differences in jealousy manifestation resulting from the discovery of infidelity online with women showing more pronounced emotional jealousy than sexual jealousy, and men more pronounced sexual jealousy than emotional jealousy (Dunn and Billett 2018; Dunn and McLean 2015; Groothof et al. 2009; Guadagno and Sagarin 2010; Hudson et al. 2015; Muise et al. 2014). These findings are supportive of sex differences consistently reported in offline jealousy-evoking scenarios (Archer 1996; Cann et al. 2001; Cramer et al. 2001; Fernandez et al. 2007; Harris 2002; Harris and Christenfeld 1996; Pietrzak et al. 2002; Schützwohl 2005; Schützwohl and Koch 2004). The findings also challenge the criticism that sex differences in jealousy are only evident using a forced-choice paradigm. Just as in the case of Bendixen et al. (2015), sex differences in the current study were found using continuous measures. In utilising Snapchat, this study has revealed that sex differences in jealousy manifestation in response to partner infidelity discovery are not restricted to text messages (Dunn and McLean 2015) or Facebook (Dunn and Billett 2018). One hypothesis, however, ‘males will be significantly more jealous over the sexual messages than females’, was not supported. A plausible explanation for this is that society may have become more sexualised over recent years (Gill 2012) and females have become more promiscuously inclined (Thornhill and Gangestad 2008) and more likely to engage in infidelity (Brand et al. 2007). Possibly, the enhanced opportunity to engage in online infidelity has resulted in both sexes becoming extra-vigilant of sexual betrayal. In a similar vein, Klettke et al. (2014) published a systematic literature review revealing no differences in the prevalence of sexting behaviour between men and women.

One unexpected finding relates to the fact that women were shown to be more jealous by the thought of infidelity occurring between their partner and their sister than between their partner and both their best friend or with a stranger. Biegler and Kennair (2016) found that when asked to list the relevance of traits either for their own or their sisters’ idealised long-term partner even though they agreed on the majority of traits, differences were reported. Participants emphasised the importance of genetic fitness for their own idealised partners compared to what they thought would be good for their sister’s idealised partner, e.g. that their sister’s potential partners would prioritise extended family members. Consequently, there would be more direct rivalry between sisters for access to the best genetic mates during ovulation and these evolved mechanisms of heightened jealousy have filtered down to the modern technological world. In summary, the current study found that female relatives appear to possess more actual and genetic conflict than male relatives (Biegler and Kennair 2016) with sisters perhaps being more emotionally invested in each other than brothers (Fletcher et al. 2013).

One finding of particular prominence and significance in the current study is the fact that men were more tolerant of the distressing thought of infidelity revealed by a Snapchat message between their partner and their own brother than they were between their partner and a same-sex stranger. This is in direct contradiction of previous research findings showing that when invited to imagine partners having cheated, participants evidenced significantly higher distress when the partner infidelity was with a relative compared to a non-relative (Fisher et al. 2009). Kostic and Yadon (2014) have argued that such higher distress may be explained by the fact that this is related to greater feelings of closeness with genetically related relatives. The current study differed in one prominent way from these earlier studies in that the jealousy-evoking scenarios were contextualised within a social media platform. The mitigation of jealousy by genetic relatedness in this case could be explained once again by adopting an evolutionary interpretation. Evolutionary psychology, like all scientific movements is guided by and owes enormous gratitude to the formulation and inception of key seminal theories. Hamilton’s (1964a, b) inclusive fitness theory is one such theory. Not only did the theory solve the seemingly imponderable mystery of the existence of altruism in nature, it also allowed researchers to construct and test intricate hypotheses relating to a range of social behaviours. One key postulate is that individuals should show greater selfish restraint, and behave altruistically, when interacting with closer genetic relatives including those who are not directly related, e.g. sibling’s offspring (Hamilton 1964a, b). In support of the theory, countless studies have shown that in a social context as genetic relatedness diminishes so does the degree of altruism directed from the donor to the recipient (Essock-Vitale and McGuire 1985; Burnstein et al. 1994; Korchmaros and Kenny 2008) with genetic relatedness being a strong predictor of subjective closeness (Stewart-Williams 2008). Apparent concerns for inclusive fitness costs pertaining to infidelity have been shown in a study where participants, regardless of their own sex, expressed most distress by a brother’s partner’s sexual infidelity and a sister’s partner’s emotional infidelity (Michalski et al. 2007). In summary, the current study illustrates that Hamilton’s inclusive fitness theory is still relevant today in the technological era of ‘Snapchat’ at least with regard to explaining male jealousy attenuation to partner/sibling infidelity. After all, extra-pair copulation between a man’s partner and a brother may still result nevertheless in genetically related offspring enhancing that man’s inclusive fitness.

Before concluding, it is worthwhile pointing out potential weaknesses in the methodology of the study. Since the incorporation of scenario methods into research pertaining to infidelity and jealousy, and in an attempt to address challenges to the evolutionary position presented by authors such as DeSteno and Salovey (1996), researchers have repeatedly attempted to present sexual and emotional infidelity scenarios as being mutually exclusive (Buss et al. 1999). When constructing infidelity-revealing messages in a social media context, it is difficult for example to create an emotional infidelity scenario without at least hinting at the potential for future sexual liaison and vice versa. In addition to emphasising message ‘ecological validity’, future studies need to further disambiguate the two by for example making it clear that sexual infidelity is restricted to sexual cheating alone without any emotional involvement. For example, current research in our laboratory uses wording contained within a message such as ‘we both know our affair will only ever be sexual’ or ‘no-strings attached’ sexual fun.

In conclusion and in support of previous findings, it is argued that manifestly different jealousy inclinations in both sexes evolved as they were advantageous during the time of our EEA to help solve adaptive problems differentially pertinent to each sex (Geher and Miller 2012; Hart 2010). Moreover, the current study has provided evidence that sex differences in jealousy extend farther than purely inclinations towards jealousy type; there may also be sex differences in the extent to which third-party identity evokes jealousy. Miscellaneous adaptations pertaining to jealousy appear impervious to change in the current technological age. With a current pandemic in social media–mediated, jealousy-elicited infidelity, research utilising fictitious, jealousy-evoking scenarios may help shed light on, and hopefully mitigate, societal and personal problems associated with this phenomenon.