In November 2011, I participated in my first Tough Mudder, an event officially billed as a "hardcore, 10-12 mile obstacle course designed by British Special Forces to test your all around strength, stamina, mental grit, and camaraderie" (and unofficially billed as "probably the toughest event on the planet"). Since then, I've participated in 3 Super Spartans and 3 more Tough Mudders, including my role as a Tough Mudder Obstacle Innovation Lab beta tester for the new 2015 obstacles, which were just unveiled online earlier this week.

Ever since the big obstacle release and the accompanying news stories, the Internet has been buzzing with chatter about the new obstacles and, as always, hypothesizing about what exactly drives us crazy Tough Mudders out to these courses time and time again. In the past year alone, there's been talk about the psychology of how Tough Mudder HQ designs the scariest obstacles, whether or not the participants ourselves are "insane," and how races like Tough Mudder became a phenomenon in the first place. As a social psychologist in such an (admittedly bizarre) scenario, it has definitely not been very hard to notice some of the phenomena that I've learned about over the years creeping into my mind and forming connections to my Tough Mudder environment.

The Power Of The Foot-In-The-Door

First of all, when thinking about a challenge like this, it begs the question...even after we had all made the decision to attempt the course, what exactly compelled us to attack some of the crazier obstacles? After all, even at the very beginning of the challenge, we were all assured that we could skip any obstacles that made us uncomfortable. I'm sure that many of us went in fully expecting to skip some of the scarier sounding the one that required running through fire, perhaps, or the obstacle that required a mad sprint through a field of 10,000 volt live wires.

One psychologically proven method of inducing compliance is something known as the foot-in-the-door technique. According to this tactic, once you've got your "foot in the door" by making an initial, small request, people are more likely to continue agreeing to successively larger requests. For example, in the most well-known classic study of this phenomenon, experimenters wanted to see if they could convince people to place large signs in their yards urging motorists who passed by their homes to "DRIVE CAREFULLY." This was generally perceived as a fairly intrusive request; when they simply asked families to install the signs in their yards, only 17% of them agreed to do so. However, when other families were asked to place a small card encouraging safe driving in one of their household windows first (a considerably less intrusive request that most of them were happy to oblige), over 75% of them subsequently agreed to install the larger sign as well.

As the logic goes, once you've gotten someone to agree to something small, they are more likely to agree to much larger requests. This could be because people feel much more involved or invested once they've made those small, initial concessions, or because the initial compliance changes the person's own self-perception -- if you see yourself as the kind of person who "does these sorts of things" (like agreeing with experimenter requests or visibly supporting safer driving campaigns), you certainly don't want to seem like a flip-flopper by changing your tune now.

How does this play into the Tough Mudder psychology? Well, as I mentioned before, all participants are assured that we can skip any obstacles that we want or drop out at any time. However, aside from some of the water obstacles during my very first November race (which many of us skipped on that particular day specifically due to the high prevalence of hypothermia), I've never seen many participants actually skipping any of the obstacles...despite how easy (and accepted) it would be to do so. I even found myself not wanting to skip any of the obstacles, despite my vehement claims before my first race that I would be skipping plenty of them. It's not hard to see how foot-in-the-door logic might apply here: Once you've done a few, smaller obstacles, you feel more committed, so you're much more likely to attempt the larger obstacles after all.

Even if that means you end up running through a field of live wires at the end of the day.

The Power of Descriptive Norms

Looking at the obstacles, it's fairly clear that most of them cannot be completed alone. After all, one perennial obstacle at these courses involves scaling a series of 12-foot walls with no ledges, footholds, or ropes.

For most of us, it would literally be impossible to complete this obstacle without help. And sure enough, throughout the entire experience, every participant is always more than willing to turn around and offer help to their fellow racers...even though at the beginning of the day, these were complete strangers. Why exactly was this cooperative phenomenon so common?

Most people know about the concept of norms: The set of behaviors that are generally considered to be "normal" or "acceptable" in a group of people. However, what most people may not realize is that there are two different types of norms -- descriptive and injunctive -- and that the former are generally much more effective at influencing people's behavior.

Descriptive norms, much like they sound, generally operate by describing the typical behaviors of a group. For example, if most of the women in a given room happen to be wearing high heels, or most of the men are wearing suits, these facts alone constitute descriptive norms. There is nothing saying that these items of clothing should be worn, merely that for the most part, they are.

Injunctive norms, on the other hand, take other people's approval or disapproval into account. In other words, what should you be wearing in that room? If all women walking into that room should be wearing high heels, or all men should be wearing suits, and anyone walking in wearing anything otherwise would be judged and scorned by the rest of the people there, these rules constitute injunctive norms because they describe what other people find acceptable or unacceptable.

Before every Tough Mudder, the group of participants (or "Mudders") gather at the start line to recite the Tough Mudder pledge.


I understand that Tough Mudder is not a race but a challenge.

I put teamwork and camaraderie before my course time.

I do not whine – kids whine.

I help my fellow Mudders complete the course.

And I overcome all my fears.

- Tough Mudder Pledge

The Mudders waiting at the start line may not realize this, but this pledge is setting a very powerful descriptive norm. What it's really saying is that all Mudders - all true Mudders, all real Mudders - help each other, cooperate, and act like adults. It's not even going so far as to say that Mudders should do these things -- all it's saying is that Mudders do. As I've blogged about before, descriptive norms are very, very powerful determinants of our behavior. Sure, we want to do things that we know others will approve of, or follow the rules. More than anything else, though, there's a little part of our brains that hasn't quite left the "Peer Pressure" halls of high school. We want to fit in, and we want to do what others are doing. If we know that all (or most) of the other Mudders cooperate, help their fellow racers, and put camaraderie before individual accomplishment? Then that's what we're going to do.

"I saw lines of ten people, dragging each other up miles of hills...strangers helping each other out, like it was, like they had been doing it for years."

As far as norm-setting goes, the Tough Mudder Pledge seems to work like a charm. This picture on the right is of Everest, one of the perennial Tough Mudder obstacles, and the caption comes straight from a Mudder's mouth in one of the promotional videos. That's the power of descriptive norms; all it takes is one pledge (and one really powerful norm) for otherwise-uber-competitive people to start acting like they've known each other forever, and cooperate accordingly.

The Power of Misattributed Arousal

I've previously blogged about misattribution of arousal, the process by which physiological arousal (a.k.a. the physical increase in blood pressure, heart rate, and/or sensory alertness, typically caused by something like fear, danger, or physical activity) can be "misattributed" to nearby people and misinterpreted as romantic attraction. Thus, it will come as no surprise that something like a Tough Mudder is probably awesome for your relationship. Want your boyfriend or girlfriend to feel intense feelings of love and desire for you? Put yourself through a grueling, 12-mile obstacle course! Once your heart rate has skyrocketed, it shouldn't be long before those warm and fuzzies start to kick in.

But there's a benefit here for your relationship that extends beyond simple arousal misattribution. According to research by Arthur Aron, "novel, arousing activities" are quite possibly the best thing that you can do for your relationship. Based on several correlational studies, couples who reported frequently engaging in "novel, arousing activities" together (however they chose to define "novel" and "arousing") were also more likely to report higher levels of relationship satisfaction. However, perhaps more convincingly, this result was experimentally confirmed as well. Couples who were randomly assigned to participate in a novel arousing task in the lab (i.e. making their way around a gymnasium-constructed obstacle course on their hands and knees...while Velcro-ed together!) not only reported being happier in their marriages than those who participated in no activity or a more boring activity, they even seemed happier to other people who observed how those couples interacted with each other before and after they engaged in the task. The researchers suggest that this effect is caused by the impact of the activities on the couples' feelings of boredom; by participating in novel, arousing activities together, the couples successfully staved off feelings of boredom, which made them feel (and act) happier together.

So, anyone who completed a Tough Mudder with his/her significant other was probably onto something: Do something novel and exciting together, and bask in the glow of your newfound relationship happiness.

Oh...did I not mention who I've done all of these races with?

Alright. So maybe I'm a bit biased towards that particular research finding.


Aron, A., Norman, C.C., Aron, E.N., McKenna, C., & Heyman, R.E. (2000). Couples' shared participation in novel and arousing activities and experienced relationship quality. Journal of Personality and Social Psychology, 78, 273-284.

Deutsch, M., & Gerard, H.B. (1955). A study of normative and informational social influences upon individual judgment. Journal of Abnormal and Social Psychology, 51, 629-636.

Freedman, J.L., & Fraser, S.C. (1966). Compliance without pressure: The foot-in-the-door technique. Journal of Personality and Social Psychology, 4, 195-202.

Image Credits

Featured Image (of TM group) by Dmitry Gudkov; available under Creative Commons license via Wikipedia.

Image of Everest by Tough Mudder LLC; available under Creative Commons license via Wikipedia.

All other photographs are the author's personal photographs.

This piece was originally posted in December 2011, about 1 month after I completed my first Tough Mudder, on my old PsySociety Wordpress blog. To see the original post, click the From The Archives icon on the left.