Don’t Judge a Man by his Swim Shorts

Judgements of people or things are made fast. So fast that they can be very inaccurate. We know we shouldn’t judge a book by its cover, but we still do. Why is that? In this blog I will explore the reasons why we judge so fast, why it can be disadvantageous and what can be done about it.


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It was a warm and sunny day. The weather was so nice that I decided to go to the beach. Just to relax and work on my tan. After two hours I decided I had had enough and started walking home along the beach. And then it happened. I passed two women in their mid-twenties lying on their sun beds. And while I passed by them I heard one of the women say to the other one, “He’s hot!“. And just when I was riding high, I got shot down by the response of the other woman, “Don’t bother, 100% gay“.

Although I would be perfectly fine with it if I preferred men over women, I just don’t. Not even considering it. But something about me convinced the woman that I was gay. Since I wasn’t interacting with them in any way, there weren’t many signals I could have given her about my sexual preference. Or maybe there was…

Yes, that is my swim short. Or to be more precise, my Tommy Hilfiger navy blue swim briefs. It is a small piece of swimwear, even for European standards. But if you want to have evenly tanned legs like I do, this is the swimwear you need. It apparently does more than just help me get a nice tan. It also conveys information. Most of us know the expression ‘don’t judge a book by its cover’. Meaning that one should not judge the value of someone or something by its appearance alone. But why do we keep doing it anyway?

The halo effect

The halo effect is a cognitive bias that causes our impression of someone or something in one domain to influence our impression of them in other domains. Psychologist Edward Thorndike started investigating the phenomenon as early as the 1920s. There are three main reasons for the halo effect to occur:

  1. Judging someone or something on just one trait makes life easy. It reduces our cognitive load.
  2. Disentangling the different traits that someone or something is composed of is really hard. Spillovers from one trait to another are very likely.
  3. Once people form an initial impression of someone or something, they often try to prove that the impression is correct. Thereby avoiding the negative feeling associated with cognitive dissonance.

The halo effect certainly has its benefits. It serves as a useful heuristic in situations when we need to make decisions quickly or when lacking certain key pieces of information. But it can come at a cost.

The downside of the halo effect

Relying on first impressions can reduce the accuracy of judgements. The risk of misjudgement is well captured in the video ‘Nerds Play Basketball In The Hood Like A Boss!‘. It shows a group of nerds arriving at a basketball court in New York. They are asked by the local players if they are lost and are looking for the library. When the nerds are told that basketball ain’t their sport, they challenge the local players for $100 that it is their sport. After an initial respite, the local players get butchered and loose the game. The end of the video shows the slyness of the nerds when they take off their thick glasses and nylon sweatbands. The nerds made good use of the halo effect by dressing a certain style, when ofcourse you can’t judge someone’s performance on a basketball court by their outfit. It took the local players $100 to learn this lesson.

How to avoid judging on the first impression

The halo effect doesn’t just take place on the beach or the basketball court. It also happens in situations where the stakes are much higher. For example, when interviewing someone for a job opening. Or when looking for a partner on a datingapp.

It is helpful to keep in mind that just because someone or something has a positive trait, it doesn’t mean that you should immediately form an overall positive impression. Same goes for a negative trait. While you can’t be aware of it all the time, you can take precautions. Disconnecting one impression from the next one improves the accuracy of your judgements. This is why more and more businesses and government agencies use tools to apply anonymously to vacancies. Disregarding name and gender in the process when considering who to invite for an interview. I personally use a form of disconnection in my own job as well. My businesspartner Niels Vink and I teach bachelor students on the subject of behavioral economics. At the end of the semester the students take an exam. There is a measure we take to avoid the halo effect when grading the exams. We first grade all the answers to the first question before we move on to grade all the answers to the second question. We continue this disconnection all the way to the answers of the final question. This way of working prevents a first impression to spill over. If for example a student correctly answered the first question, we might be tempted to interpret the second answer as better than it actually is. The result could be that a correct or incorrect answer at the first question disproportionately affects the final grade.

First impressions are important due to the halo effect. The sequence of information is thereby very consequential in forming an overall opinion. And it is not just you who gets affected by the halo effect when judging other people, it also works the other way around. By influencing the first piece of information that people encounter of you or your work can be very helpful to get where you want to be. I just hope that the evenly tanned legs make up for the swim briefs in terms of lost love.

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About the author

Sander Palm (1980) is a behavioral economist and fitness enthusiast. He has a Master of Science in Marketing from VU University Amsterdam. He lives and works (out) in The Hague. Want to know how you can get your marketing, communication and sales in better shape? Drop an email at

Source of top image: Kindel Media via



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