Like other animals, humans use their different sensory modalities to communicate information to one other, and the ways in which these sensory systems are used for communication can change depending on the situation. One scenario that occurs across many organisms are courtship situations, where animals attempt to attract potential breeding mates. Within courtship situations, different animals use a variety of different modes of sensory communication to communicate information to their potential mates. For instance, humans, among other animals, can use both olfactory cues and auditory (vocal) cues to communicate to their potential mates.
Despite not receiving as much attention as sight or sound in human sensory research, olfaction is certainly an afflicting sense; among chemical information that be communicated through olfaction, there exist pheromones, which are chemical substances that an animal produces and releases into the environment that changes the behavior of an animal of the same species. Within humans, axillary odors (a more complicated way of saying armpit sweat odor, a kind of pheromone), have been shown to elicit psychological and behavioral responses in humans, particularly to those of the opposite sex during courtship contexts. Interestingly, cultural and societal awareness of pheromones in courtship contexts has led to the development of androstadienone, a chemical component of male sweat, as a marketed and sellable product (expensive at that, too!), as empirical evidence suggests its ability to improve the mood and the facial attractive judgements of the receiver smeller, among other behaviors.
In their study, researchers Leongómez et al. (2021) examine how the presence of male body odor and androstadienone affects several measurements of behavior. Firstly, they study its effect on a female’s level of attraction to a male. They also examine the potential pheromonal effect upon the receiver’s (both within male and female receivers) speaking pitch frequency. Vocal characteristics, like pitch, can be another important means of communicating socially relevant information in different scenarios, including both courtship situations, as some previous studies showed people exhibiting changes in voice pitch in these scenarios. For instance, some psychologists and biologists accredit men lowering their vocal pitch in front of potential female mates to wanting to appear more “masculine” and therefore more attractive. Given that both odor and vocal cues both play a role in communicating information in these courtship scenarios, the researchers ask if these olfactory and vocal/auditory modes of communication are intrinsically linked in humans.
Specifically, in their study, Leongómez et al. (2021) test a “body-odor vocal modulation” hypothesis; that is, if male pheromonal communication – with or without added androstadienone – is intrinsically linked to a modulation in a receiver’s vocal speaking pitch, specifically in courtship scenarios. Thus, in their model, they predicted that in the presence of male body odor and the androstadienone, the females’ perceived attractiveness of the males would increase, and consequently, their voice pitch would be higher. Further, they predicted that male receivers of the male axillary odor would lower the pitch of their voice.
To test their hypothesis, the researchers recruited 40 male participants, and had them gather their own armpit sweat using cotton pads, collecting the odor stimuli for the study. Next, “target videos” were created, in which men were recorded “introducing themselves to attractive people of the opposite sex,” after which a separate group rated their attractiveness levels. Next, researchers had female participants sit in a room, closely exposed to the aforementioned collected cotton pads, and, upon watching these “target videos,” were then asked to audibly answer if they would “date the person they just saw” out-loud, allowing for researchers to record the pitch inflections of their voice. To examine for specific effects of odor upon their vocalizations, female participants underwent a first “control” session with odorless cotton pads, and then 7-14 days later, underwent a second session with an odor’d cotton pad. Further, to test for the effect of adding androstadienone, some females were grouped off into being exposed to the odor sample with combined androstadienone. The rest of the females were grouped off into either being exposed to “high quality” (HQ) or “low quality” (LQ) odors, which the researchers developed by taking the odor samples, and surveying them through a separate group of participants, who scored the smells in terms of “attractiveness,” afterwards combining the top and bottom three into HQ and LQ odor packs. Researchers did so to examine the effect of odor “quality” on pitch changing.
Against their prediction, in comparing the females’ pitch responses with and without exposure to the male armpit odor, researchers found that olfactory exposure had no consistent effect upon the female’s pitch inflections. Even with the added androstadienone, there too weren’t any consistent effects upon vocalization. Lastly, there weren’t any notable differences in vocal responses between the “high quality” and “low quality” odor groupings.
The results of this study provides evidence against the “body-odor vocal modulation” hypothesis; however, researchers did find a correlation between female pitch changes and the attractiveness ratings given to the target videos. These findings conflict with the (little) previous research suggesting a correlation between olfaction and vocalization in certain social contexts; the researchers cite this difference due to the experiment being conducted in an isolated cubicle, as opposed to naturally occurring, as previous research has found differing results in more naturally-occurring experiments. Thus, more research is necessary to determine the relationship between olfaction and vocal modulations in natural courtship situations. Nonetheless, given that there is an actual market demand for “natural” pheromone scents and sprays for men, further research will allow us to better understand the relationship between these scents, pheromones in general, and courtship-scenario behavior.
Leongómez, J. D., Sánchez, O. R., Vásquez-Amézquita, M., & Roberts, S. C. (2021). Contextualising courtship: Exploring male body odour effects on vocal modulation. Behavioural processes, 193, 104531. https://doi.org/10.1016/j.beproc.2021.104531