The effects of sex and handedness on masturbation laterality and other lateralized motor behaviours. Paul Rodway, Volker Thoma &Astrid Schepman. Laterality, Nov 26 2021. https://doi.org/10.1080/1357650X.2021.2006211
Abstract: Masturbation is a common human behaviour. Compared to other unimanual behaviours it has unique properties, including increased sexual and emotional arousal, and privacy. Self-reported hand preference for masturbation was examined in 104 left-handed and 103 right-handed women, and 100 left-handed and 99 right-handed men. Handedness (modified Edinburgh Handedness Inventory, EHI), footedness, eyedness, and cheek kissing preferences were also measured. Seventy nine percent used their dominant hand (always/usually) for masturbation, but left-handers (71.5%) were less consistently lateralized to use their dominant hand than right-handers (86.5%). Hand preference for masturbation correlated more strongly with handedness (EHI), than with footedness, eyedness, or cheek preference. There was no difference in masturbation frequency between left- and right-handers, but men masturbated more frequently than women, and more women (75%) than men (33%) masturbated with sex aids. For kissing the preferred cheek of an emotionally close person from the viewer’s perspective, left-handers showed a left-cheek preference, and right-handers a weaker right-cheek preference. The results suggest that hemispheric asymmetries in emotion do not influence hand preference for masturbation but may promote a leftward shift in cheek kissing. In all, masturbation is lateralized in a similar way to other manual motor behaviours in left-handed and right-handed men and women.
Discussion
The findings clearly addressed the hypotheses outlined in the Introduction. The hypothesis (H1) that people would strongly prefer to use their dominant hand to masturbate was confirmed in the data, with 79% of people always/usually preferring their dominant hand. There was no evidence for the lay belief that men often masturbate with their non-dominant hand because it will feel “like someone else”. The hypothesis (H3) that left-handers would be less lateralized for hand use for masturbation was also confirmed, with 86.5% of right-handers preferring their dominant hand compared to 71.5% of left-handers. This result corresponded to the findings of other studies that had found weaker lateralization of unimanual motor behaviours in left-handers (McManus et al., 2016).
The hypothesis (H2) that handedness for masturbation might be a purer measure of handedness than the EHI, due to it being less influenced by social factors, was rejected, with the EHI proving to be a stronger measure of handedness. This shows that despite the private nature of masturbation (Kirschbaum & Peterson, 2018), there was no greater tendency to use the dominant hand for masturbation compared to other motor behaviours. In addition, the hypothesis (H4) that greater specialization of the RH for sexual arousal and emotion would cause a shift towards greater use of the left hand, in both right-handers and left-handers, did not receive support. Unlike other behaviours, such as kissing and cradling, where the emotional context influences lateralized motor behaviour (Ocklenburg et al., 2018), this appeared not to be the case for masturbation. This might be because cradling, kissing, and embracing are social behaviours, whereas masturbation is primarily a private behaviour.
Finally, the hypothesis (H5) that females would show greater use of their dominant hand for masturbation than men, particularly for manual masturbation, due to a greater need for fine motor control, was not supported. Males and females preferred using their dominant hand to a similar extent (77% males, 81% females). Interestingly, however, for the use of sex aids women were found to use their dominant hand more than males. A possible reason for this difference is that when using a sex aid, males may be more likely to manipulate their genitalia with their dominant hand, and hold the sex aid in their non-dominant hand to stimulate other regions.
In addition to showing a weaker hand preference for masturbation, left-handers were also less strongly lateralized than right-handers for footedness. This replicates observational findings (Nachshon & Denno, 1986) and strengthens the view that the data accurately reflect the participants’ behaviour. For eyedness the degree of lateralization did not differ significantly between left-handers and right-handers. This might be because eyedness is not as closely related to hand preference as is footedness (Nachshon & Denno, 1986), making the relationship between eyedness and handedness less consistent in both left- and right-handers.
For cheek kissing an interesting lateralization pattern emerged. Research studies have found that head tilting during kissing is influenced by handedness (Ocklenburg & Güntürkün 2009), and embracing is influenced by emotional context, with a leftward shift in emotional embraces (Packheiser et al., 2019). Both of these influences were observed in our data on cheek kissing. There was an overall bias for participants to kiss the left cheek (from the perspective of the kisser) of a person they were emotionally close to who was facing them. This effect was qualified by a significant effect of handedness, with left-handers showing a significant tendency to kiss the left cheek and the right-handers the right cheek, with the stronger tendency in the left-handers carrying the overall left-cheek bias. In addition, compared to the stronger rightward lateralization of handedness, footedness and masturbation, for cheek kissing there was an overall stronger leftward lateralization. This leftward bias in cheek kissing is consistent with the right hemisphere hypothesis of emotional asymmetries, with the greater involvement of the RH biasing motor behaviour towards the left (Ocklenburg et al., 2018). A further possibility is that it is related to a more general leftward bias when interacting with visual stimuli (Ciricugno et al., 2021; Jewell & McCourt, 2000; Nicholls & Roberts, 2002; Rodway & Schepman, 2020). Both interpretations require further research to determine the cause of this effect.
Chapelain et al. (2015) previously used a self-report measure of cheek kissing, similar to the one used in the present study. They measured choice of cheek and number of kisses for social greetings from various regions throughout France, and found an effect of region on cheek choice but no effect of handedness. The discrepant effects of handedness between Chapelain et al.’s research and the present study can be explained by the fact that cheek kissing for a social greeting, involving multiple kisses, is a very different interaction from a single kiss on the cheek of an emotionally close person. Importantly, the results from the present study replicate previous effects of handedness on lateralized kissing biases (Ocklenburg & Güntürkün 2009; Karim et al., 2017), with our study using a different task and a large sample of left-handers.
Other results were also in line with expectations and showed that the data calibrated well with previous research. Men were found to masturbate more than women, replicating previous findings (Leitenberg, et al., 1993; Driemeyer, et al., 2017) and a similar frequency of sex aid use by males for masturbation (33%) was found to that reported by Herbenick et al. (2017). The use of sex aids by women in our sample (75%) was somewhat higher (52.5%) than reported by Herbenick et al. (2009), and the 50.2% of vibrator or dildo use reported in Herbenick et al. (2017). This could be due to several factors, such as our participants self-selecting to opt into a study about masturbation, an increase in the use of sex aids over recent years, cultural differences between the US and the UK, and the fact that our data were collected during the coronavirus / Covid-19 pandemic.
In a survey of sexual behaviours of people in the United States, a substantial proportion of men (82.3%) and women (60.4%) reported having watched pornography (Herbenick et al., 2017). In the present study, participants were asked which hand they typically used to masturbate and which hand they typically used if they were not holding anything else. This was to check, for those participants who masturbated while viewing pornography (and which could involve the use of their dominant hand to control a computer mouse, or hold written material), if there was an increase in the use of the dominant hand when they were not holding anything else. However, we found no significant difference overall between these questions. Our data therefore suggested that preferred hand use for masturbation was not strongly determined by holding other objects and that participants continued to use their dominant hand for masturbation even when they might be holding something else. A possible limitation, however, is that we did not directly ask which hand they used when viewing pornography, and it is possible that if we had asked this question there might have been evidence of a shift towards using the non-dominant hand.
In the majority of left- and right-handers, eyedness and footedness was congruent with their handedness, replicating previous findings (Bourassa, McManus, & Bryden, 1996; Porac, 1997). In addition, hand preference for masturbation correlated more strongly with scores on the modified Edinburgh Handedness Inventory, than with footedness, eyedness, or kissing. Masturbation had a strength of hand preference (53 for typical hand) that fell between that shown via the modified EHI score (71), and both footedness (32) and eyedness (33), with significant differences between masturbation with the typical hand and modified EHI. This suggests that, although dominant hand preference for masturbation was weaker than that measured via the modified EHI, it may nevertheless be a reliable measure of hand preference in general. It can also be noted that historically in some cultures, such as India and ancient Rome, masturbation has been specifically linked with using the left hand (Derrett, 2006). Despite this historical association, there was no evidence in our sample of UK participants that such an association caused large numbers of right-handers to use their left hand.
An interesting incidental finding is that there were no differences in masturbation frequency between left- and right-handers for either men or women. Occasionally, research has tended to pathologise left-handedness (see Porac, 2015 for a discussion), rather than treating it as a natural variation that provides fitness benefits (Groothuis, et al., 2021), with an emphasis on health issues (Peters et al., 2006) and increases in atypical sexual behaviours (Fazio, Lykins, & Cantor, 2014). Also, some theories of the origin of left-handedness have linked it to increased levels of prenatal testosterone (see Grimshaw, Bryden, & Finegan, 1995; Richards et al., 2021, for discussions). As higher levels of testosterone in adults have been associated with more frequent masturbation (O’Connor, et al., 2011), theoretically, although via a speculative leap, it could be hypothesized there might be a difference in masturbation frequency between left- and right-handers. There was no evidence of this in the data, which is in line with the body of research showing that left- and right-handers are much more similar to each other than they are different (see Porac, 2015 for a review).
There are a number of potential limitations with the present study. The results might be specific to our UK sample and our exclusion criteria, which asked prospective participants whose culture or beliefs strongly determined which hand they used for certain actions not to take part. This was to elicit reports of natural, rather than culturally-conditioned behaviours. It may be that cultures that associate using the left hand with activities that may be classed as impure could show different patterns of behaviour, perhaps with a higher proportion of right-handers using their left hand for masturbation. The data were also based on self-report, rather than observation, for obvious ethical and moral reasons, raising the possibility they did not accurately represent participants’ behaviour. However, the results calibrate well with findings from other research, which gives confidence in their accuracy and validity. In addition, it is likely that the anonymity and privacy of the survey enabled participants to feel more able to respond honestly to the questions, than if the data had been collected in a less anonymous way, even if this had been ethically and morally acceptable. Thus, the constraints placed on the data acquisition method may not necessarily have been a hindrance in the collection of reliable data.
To summarize, hand preference for masturbation was strongly lateralized, with most people preferring to use their dominant hand, perhaps because it affords greater motor control, or because they use that hand for most activities. Right-handers were more strongly lateralized than left-handers for masturbation, EHI, and footedness, but left-handers more for kissing. There was no evidence for masturbation being more strongly lateralized than the behaviours measured by the Edinburgh Handedness Inventory. A small proportion of people chose to use their non-dominant hand for masturbation. This was not due to other objects occupying their dominant hand. There was no evidence that specialization of the RH for sexual arousal or emotion caused a shift towards greater use of the left hand for masturbation. However, there was a general leftward shift in cheek kissing. This finding is compatible with the RH hypothesis of emotional lateralization, with the greater involvement of the RH during the emotional behaviour of kissing, biasing motor behaviour towards the left. Therefore emotional context may influence lateralized motor behaviour particularly in social settings (such as kissing), rather than in a setting which can induce emotion but which is private (masturbation). In all, masturbation shows a similar pattern of lateralization to other unimanual behaviours in left-handed and right-handed men and women.
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