Losing stinks! Literally – The science of odor cues in MMA competition

Maybe we could harness this science to fix MMA judging. Who needs a 10-point must system when we can find the loser based on smell alone?

By: Christopher A Baker | 4 weeks ago
Losing stinks! Literally – The science of odor cues in MMA competition
Illustration by Chris Rini

If losing wasn’t bad enough, it turns out it also makes people smell bad. But don’t worry losers, just getting in the ring and scrapping also makes people smell more manly—so it’s not all bad news.

What does the science of smell mean for the fighters out there? Let’s sort it out.

The sense of smell starts in the olfactory bulb in the front of the brain. Unlike other senses (i.e., seeing, hearing, taste, touch), olfactory cues go directly to the limbic system, including the hippocampus and amygdala, the areas responsible for memories and emotions, respectively. This is one reason why scents evoke such intense recollections, and reactions.

Like the smell of food that instantly puts a smile on the face as it triggers happy childhood memories of grandmother’s house. Or the jolt of emotions conjured by the random passing of a stranger wearing an ex’s perfume, inevitably resulting in getting hammered and staying up all night to weep over Vanilla Sky.

Ask someone to think of a memory associated with the feel of popcorn, there is not much there. Ask them to think of a memory associated with the sound of popcorn, a little there. The sight of popcorn, there is something there. The smell of popcorn, boom, out come the recollections. Yes, we humans like our scents. We love the smell of garlic sauteing in a pan, but we also love the smell of gasoline. Go figure.

1200px Olfactory system.svg
Illustration by Patrick J. Lynch via Wikimedia Commons

Odors are information

We know the sense of smell serves as a change detector. It helps identify when new information has entered the scene. This is why your nose is very sensitive to cologne the first time you spray it, but it seems like it wears off after about 20 minutes. It hasn’t, really, your nose just isn’t interested in it anymore. Or I should say more accurately, your brain via your nose isn’t interested in it anymore.  

If odors have a special network in the brain, it’s because they play a special role in animal survival. Secreted chemical odorants (i.e., pheromones) are central to animal mating practices. They also play a role in dominance assessments. For example, rodents can differentiate dominants from subordinates by odor alone, even if they never meet.

Pheromonal glands in social insects
Illustration by Nesreen M. Abd El-Ghany via Wikimedia Commons

Humans are attracted to and repulsed by scents as well. Our odors have the ability to convey information and the power to elicit emotional reactions in others. For example, humans can use odors to signal dominance just like rodents and insects. Research shows that heterosexual women prefer the odor of dominant men during ovulation, while heterosexual women in non-fertile phases show no such effect.

There is also evidence that odors can signal when humans enter a competitive or aggressive state. For example, compared to odors released during non-competitive activity, odors released during competition elicit a bigger physiological reaction in those judging the smells. Furthermore, odors released during bouts of aggressiveness can interfere with high-level cognitive processing in those judging the smells. This is typically interpreted as an indication of a threat response, where the brain redirects cognitive resources from higher-order cognitions to more basic survival-based thinking.

It’s important to note that while olfactory cues play a role in human communication, they do not play as large a role as they do for non-human animals. This is partly due to humans having many routes for communicating feelings and emotions, whereas those routes are more limited in our animal counterparts. Nonetheless, when it comes to base aspects of human survival and reproduction, odors matter. But of course you already knew this—all we would have to do is check your medicine cabinet.

Odors and MMA outcomes

Fialová et al. (2019) were the first researchers to explore the meaningfulness of olfactory cues during MMA competitions. In this study the researchers collected samples from 40 amateur male MMA fighters during multiple rounds of an amateur MMA-league competition. They also recruited 138 participant judges whose job it was to rate odor samples from these matches. It’s important to note here that all fighters in this study were men, while the judges were overwhelmingly women. As such, results should perhaps be generalized only to individuals represented by this gender dynamic.

Readers might be wondering how someone “collects odors”, particularly of fighters in an MMA competition. To accomplish this, all fighters were required to wear a 100% cotton t-shirt during their matches. Afterward, the sweat-soaked shirts were placed in a sealed zip-lock bag and then stored in a refrigerator until the samples were needed for evaluation. When it was time for the sweaty stimuli to be evaluated, each participant judge received a rating sheet with instructions to judge each sample for (1) pleasantness, (2) attractiveness, (3) masculinity, and (4) intensity.

What does the science say?

1. After a match, odor pleasantness, attractiveness, and intensity all decreased, but masculinity increased, and this occurred for both winners and losers. Said another way, fighting may make you stink, but it also makes you smell more masculine, whether you win or lose.

2. Match losers tended to stink more. Their samples were rated as less pleasant and less attractive after a match, compared to match winners. Said another way, fighting may make you stink, but you stink worse if you lose.

3. These findings provide new converging evidence that human olfactory cues are similar to those of other mammals, and can provide cues to dominance and competition-related outcomes.

This work contributes to a body of literature showing that many aspects of human information-processing occur outside of conscious awareness. For example, the size of a person’s pupils can signal when they’ve recognized a familiar face. The deceleration of heart rate can signal when someone sees something interesting. And now it also appears that the odors the body releases can signal if someone is willing to throw down, and maybe even if they’re likely to win that scrap.

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About the author
Christopher A Baker
Christopher A Baker

Christopher A Baker, PhD is a cognitive scientist at UIC studying memory and indicators of in-group/out-group status. He is an avid fight fan and failed high school wrestler.

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