We’ve recently taken up the chemical senses (olfactory and gustatory), so I was motivated to look up on an article that had to do with smell. After all, there are certain smells that we all don’t like: poo, puke, spoiled stuff, etc. Not only that, but we Filipinos agree that we’re really sensitive to smell, most especially when those smells aren’t a good thing.
When adults smell poop, sweaty feet, or garbage on a hot day, their reactions can be reliably predicted: intense dislike. However, this isn’t the case for kids, infants, and neonates, because their reactions are harder to predict. In the most rigorous and recent study on neonates, it was found that neonates' facial responsiveness to odors that adults find pleasant or unpleasant provided few indications of adult-like preferences. Studies involving preschool kids are mixed: one study found no evidence of dislike for sweat or fecal-type odors but other studies found that children as young as 3 to 4 years were similar to adults in their rank-order preference for a range of odors. Notably, the size of the “hedonic interval” between odors increased with age, suggesting that children were more tolerant of malodors than adults. Data obtained from older children are more consistent. Different studies from different decades all reported that by age 7, children's hedonic responses are similar to those of adults. These findings converge with conceptually related studies of disgust development (in which children's understanding of contamination was assessed). It was found that contamination sensitivity increases markedly from ages 3 to 9. The implications of these intervals and increases? Contamination sensitivity and the formation of adult-like hedonic responses to certain odors (especially fecal and body odors) may be related to the understanding of the contaminating nature of the odor's source. In other words, our dislike for certain orders could be because we know and understand that those smells are supposedly bad. This is mediated by age, because we learn more about what’s “good” and what’s “bad” as we grow older.
The bottom line: we’re not exactly sure about about the point in development when adult-like hedonic responses become apparent, but there is consensus that age-related changes in hedonic response to odors do occur. The study I’m going to discuss looks exactly at the latter. Stevenson and Repacholi designed experiments that examined changes in hedonic responsiveness to male sweat before and after puberty. In simpler words, they asked the question along the lines of “Does the response to male body sweat depend on age/ change as we get older?”
Why male sweat? One reason is that male sweat is an odor that many adults find repellant, as confirmed in studies (sorry guys). Another is that that changes in the hedonic response to sweat may occur relatively late in childhood. Why? Apocrine sweat glands, the major sources of odorous sweat, are relatively benign before puberty. Thus, children have relatively little exposure to odorous sweat at such time. After puberty, sweat, especially in males, starts to smell pungent because of bacterial action on the apocrine secretion. Thus, puberty is likely to be the first time that most individuals routinely encounter this odor. In addition to this smell, considerable energy is spent on advertising products that mask body odor. There also are widely held beliefs about the negative meaning of body odor. Thus, the odor of male sweat should begin to elicit intense dislike sometime during or after puberty.
How are intense dislikes toward odors acquired? According to Kirk-Smith and Booth, two steps are involved: first, the odor must be experienced. Second, this experience must acquire meaning. This means that the odor has to be correctly named or identified, as meanings come with their labels. Note that in natural conditions, labeling would not be important, but when odors are studied in the lab, out of context and without accompanying visual cues, they are actually notoriously hard to identify. Stevenson and Repacholi took note of this in their experiments too.
So what did they find? When no cues were given about the identity of the odors (participants did not know what they were smelling), all male and female children, adolescent males, and adult males disliked male sweat to a similar extent. Adolescent females and adult females intensely disliked the odor and were more able (than the other ‘groups’) to correctly identify that the odor was male sweat. When odor identity was cued, or when participants were told that what they would smell was from used clothing, both male and female adolescents intensely disliked the smell. Cuing had not much effect on children. They rated the smell as less unpleasant than did adolescents, and they also reported that they were less familiar with the odor. These findings support the claim that hedonic responsiveness to odor is affected by developmental change. According to literature, this is consistent with a model of olfactory hedonics ‘in which the acquisition of meaning is important to the development of intense dislikes’. Labeling did not affect the children’s response because of a lack of exposure and a lack of meaning between the smell and its label. The key exposure to male sweat probably occurs in males largely through their own sweat and in females through incidental or intimate exposure to males. During this period, both male and female adolescents also are probably learning an association, primarily between the label sweat and the pungent odor of male sweat. This learning is presumably accompanied by the formation of negative attitudes to body odor from peers, parents, and the media. The result? By late adolescence, certain body odors (from strangers) in certain circumstances (public transport) come to invoke intense dislike. Finally, let’s not forget how the results proved the importance of labeling. There were gender differences in the hedonic response to male sweat- the female adolescents disliked the smell more and were more able to identify it. This better identification among females is an ability that has been linked to their enhanced retention of odor names and reaction to the odors. Not only is male sweat probably an acquired social response, but this judgment is also affected by the ability to identify the odor. If we didn’t know we smelled sweat, we probably wouldn’t necessarily find the smell extremely disgusting, compared to if we knew what the smell was.
I honestly found this study so intriguing because it had to do with body odor. After all it’s not just interesting finding out things about what we like, but also about what we don’t like. And the thought that responses to male sweat could be affected by age was interesting too. This could mean so many things: could we care less about the smell if our word for it had a positive connotation, if we didn’t know where the smell came from, if our culture didn’t find the smell bad? I liked that the researchers didn’t just see if exposure to a certain smell and knowledge and meaning of that smell affected our perception of smell- they also considered the literature behind the smell, and picked a smell that whose perception by receivers could be affected by age because of the biology and physiology of the person. I liked that the researchers took care in making sure about their results by having different comparison smells, etc., and by taking into consideration the meaning of a smell as determined by its label. Finally, I liked that this study was once again, proof that our perceptions are not just determined by a single mechanism. Receptiveness to a smell wasn’t just about the nose. It had to do with knowledge of the term and prior experience (top-down knowledge, not just bottom-up), and it also had to do with vision (lack of visual cues makes it hard to identify where smells are from, which affects how we react to the smell). Of course, it was also quite entertaining reading the process of obtaining the body sweat of males. Three of them were not told to eat certain foods (such as spicy ones) for so long, and then they all washed with a non-smelling soap, and then they were all given tight, white cotton shirts to wear as they exercised for an hour. MMM. Haha.
I liked that this study has so many implications. Knowing that we react more negatively when we know the source of a bad smell, does that mean that it’s really a case of “mind over matter”, since cues and labels affect our perception of smells? Do labels and experience extend to other types of bad smells? Would there be a difference between the reactions of males and females such as in the case of our culture where we are easily offended by bad smells? Or would we be affected similarly, in the sense that if we did not know that such smells were considered bad, or that if we could not pin point the smell or where it comes from, then we would be less “offended”? Do we find bad smells bad because we grow up learning to dislike them, like others around us do? And how does culture come into play? Because certain cultures find certain smells “normal”, unlike other cultures. It’s crazy knowing that a smell we would think is universally bad isn’t after all. I wonder if in the future, results from more advanced studies can help us figure out how to be less offended by certain smells. Is it by changing a label, not having a label, lack of exposure, or exposure to the point of desensitization, taking out other cues? It’ll be great because smells really affect the way we deal not just with situations but with people. It can be mean, but what can we do if we can’t stand those smells? Or can we deal with them after all?
True to what we’ve discussed on our last day of class, perception is intertwined in every topic, and in anything we do. Who knew how even studies on smells could imply so much, now that we know that they depend on ages and labels and cues and meanings. Not only is perception everywhere, but smell in itself is not a solo sensation- it depends on so many things too.
Stevenson, R., & Repacholi, B. (2003). Age-related changes in children's hedonic response to male body odor. Developmental Psychology, 39(4), 670-679.
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