Friday, April 23, 2021

Multimodal mate choice: Exploring the effects of sight, sound, and scent on partner choice in a speed-date paradigm

Multimodal mate choice: Exploring the effects of sight, sound, and scent on partner choice in a speed-date paradigm. Tom S. Roth, Iliana Samara, Mariska E. Kret. Evolution and Human Behavior, April 23 2021.

Abstract: When people meet a potential partner for the first time, they are confronted with multiple sources of information, encompassing different modalities, that they can use to determine whether this partner is suitable for them or not. While visual attractiveness has widely been studied with regard to partner choice, olfactory and auditory cues have received less attention, even though they might influence the attitudes that people have towards their partner. Therefore, in this study, we employed a combination of pre-date multimodal rating tasks followed by speed-date sessions. This offered a naturalistic setup to study partner choice and disentangle the relative effects of a priori attractiveness ratings of sight, scent and sound on date success. Visual attractiveness ratings showed a strong positive correlation with propensity to meet the partner again, while the effects of olfactory and auditory attractiveness were negligible or not robust. Furthermore, we found no robust sex differences in the importance of the three modalities. Our findings underscore the relative importance of visual attractiveness in initial mate choice, but do not corroborate the idea that static pre-date measures of auditory and olfactory attractiveness can predict first date outcomes.

Keywords: Mate choiceRomantic loveMultimodal perceptionOlfactory cuesAuditory cues

4. Discussion

Choosing a romantic partner is an important life decision. Previous research has mainly focused on the role of physical attractiveness during early stages of partner choice (Asendorpf et al., 2011Kurzban & Weeden, 2005Sidari et al., 2020). However, recent evidence reveals that attractiveness is multimodal, further involving scent and sound (Groyecka et al., 2017). Therefore, here, we examined the effect of multimodal attractiveness ratings of static samples in an ecologically valid speed-date setting (Finkel et al., 2007) and asked participants to indicate whether they would like to meet their dating partner again. To our knowledge, this is the first study that examines the effect of sight, sound and scent on speed-date outcomes. Our results are threefold. First, we show that there were only low levels of covariance in the different modalities of attractiveness. Second, using a partial model and independent models, we show that pre-date visual attractiveness ratings correlate strongly with propensity to meet again, while no strong effects were found for vocal and olfactory attractiveness. Third, in the partial model we found no robust sex differences in the importance of the different modalities. In the independent models, however, we did find robust sex differences for the effects of visual and olfactory attractiveness. Here, we discuss these findings and further address possible limitations of our study.

In the current study we observed that visual attractiveness correlated positively with auditory attractiveness and olfactory attractiveness, respectively. This finding is in line with the back-up cue hypothesis (Candolin, 2003Johnstone, 1997). However, it is important to note that the effect sizes were very small when compared to previous studies (Collins & Missing, 2003Cornwell et al., 2004), and it is therefore questionable whether such low correlations have any practical relevance. In addition, we did not find clear differences between sexes, while some of the previous studies only described such concordance of multimodal attractiveness ratings in a specific sex (e.g., Collins & Missing, 2003). Larger studies may be better suited to detect such nuances in future work.

Our most prominent finding is that, from all three modalities, facial attractiveness showed the strongest correlation with willingness to date again across both genders. This is in line with previous findings from speed-date paradigms (Asendorpf et al., 2011Luo & Zhang, 2009), and experimental paradigms incorporating multimodal attractiveness ratings (Foster, 2008). This finding is not surprising, given that humans are extremely visually-oriented beings, rendering sight the most conspicuous source of information in mate choice (Krupp, 2008). Thus, our results corroborate the relative importance of facial attractiveness compared to scent and sound during initial phases of partner selection. Indeed, in a busy public place, such as a bar or a speed-dating event for that matter, visual information is the most apparent and reliable cue upon first acquaintance, because auditory cues might be distorted by noise and olfactory cues will be difficult to perceive in isolation (Thomas-Danguin et al., 2014), given the fact that mixing with other people's odour might obfuscate individual olfactory cues.

In line with this notion, we found little evidence to support the multimodal nature of attractiveness during speed-dates. Auditory attractiveness seemed to slightly influence partner choice decisions in men: they were more likely to indicate their willingness to go another date if they rated their female partner's voice as attractive. However, the effect was small, especially when compared to the effect that visual attractiveness had on male partner choice decisions. For women, no clear effect of auditory attractiveness on their partner choice decisions was observed in the partial model, although the independent model showed a similar pattern for both men and women. These findings are somewhat consistent with previous research (Asendorpf et al., 2011), that found a smaller effect of vocal attractiveness than visual attractiveness, although the effect of vocal attractiveness was significant. It is important to note, though, that Asendorpf et al. (2011) obtained visual and auditory attractiveness ratings from an independent group of raters, while we used individual attractiveness ratings to predict dating outcome. Therefore, it is not clear whether these findings are directly comparable. However, the fact that a study using independent raters finds a similar strong effect of visual attractiveness on date outcome shows how important facial attractiveness is, and at the same time suggests it is unlikely that potential demand characteristics underlie our main result.

Furthermore, the effect of auditory attractiveness on dating outcomes might be obfuscated by voice modulation and interpersonal dynamics during speed-dates. People modulate the pitch of their voice when addressing a desirable partner (Fraccaro et al., 2011Leongómez et al., 2014Pisanski et al., 2018). In addition, the presence and sound of other people, and a camera recording the interaction, might have further affected the mental states of the participants and, consequently, their voices. Therefore, it is likely that participant's spoke differently (e.g., different pitch) during the audio recordings and the actual dates, leading to the discrepancies in perception of the recorded voice and the voice that was heard on the date on the rater's end. Thus, using an isolated rating task for voices might have slightly obscured the importance of voice during the actual dates. Future research should compare how isolated measures of vocal attractiveness relate to vocal attractiveness in an explicitly social context such as a date.

We found a small effect of olfactory attractiveness on willingness to date again for women, but not for men. Interestingly, the relationship that we found for women was negative: they were less likely to want to go on another date with men whose smell they rated as attractive. This direction of the effect is surprising given previous evidence suggesting that scent plays an important role in mate selection for women (Havlíček et al., 2008). It is unclear why this effect might have occurred. One possible explanation is a methodological one: the olfactory samples employed in the present study should be perceived as indicators of diplomatic body odour (Gaby & Zayas, 2017). Diplomatic body odour samples might be more ecologically valid than natural body odour samples, as odours are heavily affected by the use of hygiene products and personal habits in real life, which may interfere with olfactory cues for mate choice (Allen, Cobey, Havlíček, & Roberts, 2016Gaby & Zayas, 2017Sorokowska, Sorokowski, & Havlíček, 2016). With regard to the negative correlation we found, it can theoretically be possible that men who know they have a strong body odour used extra hygiene products when wearing the t-shirt, even though they were instructed not to. This would then result in high attractiveness ratings for odour, while the actual smell perceived on the date would be unpleasant. Note that this explanation does assume that women actually perceived the natural odour during the date. Because we have no compliance data for the t-shirt preparation, we can unfortunately not exclude this explanation. Such potential dicrepancies between different types of body odour highlight the difficulties of studying the effects of olfaction on human mate choice (Ferdenzi, Richard Ortegón, Delplanque, Baldovini, & Bensafi, 2020), and future studies could consider incorporating both natural and diplomatic samples.

Importantly, some important questions about multimodal attractiveness and initial attraction remain. For example, a question that we have not investigated is how cross-modal interactions shape attraction. Given our sample is relatively small, we could not examine such complex relationships. Nonetheless, investigating such dynamics might be vital to grasp the complex dynamics of multimodal attractiveness (Groyecka et al., 2017). For example, having an attractive voice and an attractive face might especially increase dating success, or unattractiveness on one modality might reduce the positive effect of the other modality (Demattè, Österbauer, & Spence, 2007). We suggest that large-scale studies using a similar design to our studies are necessary to further elucidate these complex interactions. Another example concerns the context-dependent importance of the different modalities. Visual and vocal attractiveness might be especially important during first interactions in which close contact is rare. Olfactory attractiveness, however, may be important during more advanced stages of the relationship (Groyecka et al., 2017), when close contact is more common, or during first interactions with close physical contact. Altogether, investigating cross-modality interactions and context-dependence are essential to understand how multimodal attractiveness shapes initial attraction.

In conclusion, our results corroborate the importance of visual attractiveness in early stages of mate choice. At the same time, the static attractiveness ratings for auditory and olfactory attractiveness did not substantially predict date outcome. This suggests that especially visual attractiveness is relatively important during speed-dates, while auditory and olfactory attractiveness are less important. Nonetheless, these modalities might come into play in other stages of the developing relationship or in other contexts. Furthermore, attractiveness of voice and smell may be more strongly influenced by dynamics during an interaction, rendering static attractiveness ratings to be less predictive. Altogether, our findings illustrate that the coupling of multimodal rating tasks and speed-date paradigms is a fruitful method of studying multimodal human mate choice. Applying such methods with large-scale samples allows for disentangling the effects of different factors on date outcome, and could further aid in understanding how human mate choice is affected by sight, sound, and scent.

Most insults targeted at men derogated formidability/status and sexuality/gender, and most insults targeted at women derogated physical appearance and ascribed promiscuity

Harrison, M. A., & Hughes, S. M. (2021). Ugly or weak? Insults target sex-specific cues of mate value. Evolutionary Behavioral Sciences, Apr 2021.

Abstract: Insulting comments are meant to demean a target. From the lens of evolutionary psychology, we theorized that the most used insults could be tied to evolved, sex-specific cues of mate value. We predicted that participants would ascribe as more insulting to men or to women phrases that derogate sex-specific cues of mate value. We analyzed both qualitative and quantitative data from 136 survey participants (age M = 21.2, SD = 6.1). Predictions were supported by notable consensus, and there were largely no sex differences in insult use. Most insults targeted at men derogated formidability/status and sexuality/gender, and most insults targeted at women derogated physical appearance and ascribed promiscuity. These qualities have been shown to be salient cues to mate viability for each sex, respectively. Limitations and future directions for research are discussed.

From 2015... The love-darts of simultaneous hermaphrodites like land snails seem to have evolved as a result of conflict over the fate of donated sperm

The love-darts of land snails: integrating physiology, morphology and behaviour. Monica Lodi, Joris M. Koene. Journal of Molluscan Studies, Volume 82, Issue 1, February 2016, Pages 1–10, August 25 2015.

Abstract: Several land-snail species of the helicoid and limacoid superfamilies possess one or more love-darts, which seem to have evolved as a result of conflict over the fate of donated sperm and/or as a way to select the most fit sperm donor. A love-dart is a calcareous stylet used during mating encounters to pierce the partner's body wall. When used, it carries accessory gland mucous products that influence the partner's physiology. Most of the knowledge on the effects of the glands' mucus derives from a single well-studied species, Cornu aspersum, in which the mucus increases the male reproductive success of the dart user. However, detailed descriptions on the use of the dart are limited to just a few other species. Hence, here we compare physiological, morphological and behavioural aspects concerning love-darts in several dart-bearing species. Patterns in the use of the dart are identified according to family and we discuss the coevolution of the morphology of the dart and anatomical traits of the reproductive system. The reported physiological effects caused by the dart's mucus suggest a common function of the dart in increasing male reproductive success. Nevertheless, caution is needed when generalizing the use and effects of the love-dart, which are predominantly based on one model organism.


The comparative approach taken here indicates that the common feature in dart shooting across families is the enhancement of male reproductive success by transferring mucus from the shooter to the recipient, inhibiting the destruction of received sperm. The precise mechanisms may be family-specific or conserved across families (e.g. Kimura et al., 2013Kimura et al., 2014, respectively). In vivo and in vitro investigations in this direction have only just begun, but are already showing promising results by highlighting differences and commonalities with the well-studied species Cornu aspersum. In this respect, particular families of interest to be investigated are the Helminthoglyptidae and Hygromiidae and the superfamily Limacoidea, for which no information is available.

The relationship between the shape and size of the dart, its manner of use and other traits of reproductive anatomy show some consistent differences among families. While the patterns are all consistent with expectations based on sexual conflict (Koene & Schulenburg, 2005), the evolution of such coadaptations cannot yet be traced. The relationships between dart-bearing families are still unclear and thus the ancestral conditions cannot be determined. While there is an ontogenetic homology in the tissues forming the dart and its accompanying structures, darts as such might have evolved more than once as a strengthening of noninjurious, external hormonal secretions. More work on phylogeny is needed.

More behavioural observations on the use of the dart are also necessary, especially for those species with multiple love-darts (e.g. the helicoid Humboldtiana). The quantification of the costs of receiving a dart has only just begun (Kimura & Chiba, 2015) and needs to be done for different species; it would be desirable to measure any immune or stress response following dart receipt (e.g. resulting from any bacterial infection due to the wounding by the dart). In our opinion the most promising and fruitful direction of investigation among all the aspects reviewed here is the physiological response of the receiver induced by the mucus delivered with the dart. As suggested by recent results, the dart seems to cause physiological changes that favour male reproductive success in more species than just C. aspersum. A broader study in this direction should assess the function of the dart in multiple species. Not only complete mucus extracts, but also the recently discovered LDA peptide (responsible for one of the physiological changes in both C. aspersum and Theba pisana), could be used experimentally. This opens up a new area of study that can investigate the expression and similarity of LDA in different dart-bearing species. This will enable a comparison across families at the allohormone level and is expected to shed light on the evolution of such substances. Such analysis can be further expanded when the peptides and proteins in the mucus responsible for different responses are identified, such as for muscular contractions, mating inhibition and increased sperm storage or paternity. To broaden our understanding of love-darts, a comparative approach across superfamilies will provide more reliable general conclusions than can at present be drawn based mainly on studies of C. aspersum.

Authors discuss the possible role of skill in determining mating success; they highlight functional similarities between fighting and mating behaviours

Skilful mating? Insights from animal contest research. Sarah M. Lane, Mark Briffa. Animal Behaviour, Apr 22 2021.


• Fighting and mating both involve the performance of repeated behaviours.

• Performance rate (vigour) and skill are of known importance for fighting success.

• Here, we discuss the possible role of skill in determining mating success.

• We highlight functional similarities between fighting and mating behaviours.

• We then identify mating behaviours for which a role for skill is strongly implied.

Whenever resources are limited and indivisible, fighting will evolve as a means to resolve ownership. Among such resources are mates, and individuals (usually males) of many species compete agonistically with rivals in order to gain access to potential mates. However, securing access is not necessarily enough to guarantee a mating or, if a mating is obtained, to guarantee that it is effective for securing reproductive success. Thus, in addition to fighting, individuals participate in a wealth of behaviours to maximize their reproductive success, from courtship to sperm competition to mate guarding. In recent years, the striking parallels between fighting and mating behaviour have become a subject of discussion. In particular, insights have been drawn from the predictions of contest theory to help us understand the use of repetitive signalling in courtship. Here, we take this discussion further, highlighting similarities between fighting and mating in the use of dynamic repeated behaviours, which function to (1) advertise quality and (2) convince or coerce an individual to relinquish the contested resource (gametes in terms of mating). We focus specifically on a performance trait of emerging interest in the field of animal contests, skill. We identify behaviours used throughout the mating process in which skill is likely to be of importance for securing success, and highlight key questions for future study.

Keywords: conflictcontest behaviourdynamic repeated behaviourfightinglimited resourcereproductive behavioursignallingskill

Check also from 2015... The love-darts of simultaneous hermaphrodites like land snails seem to have evolved as a result of conflict over the fate of donated sperm

The love-darts of simultaneous hermaphrodites like land snails seem to have evolved as a result of conflict over the fate of donated sperm