At one point, I thought a blog thing that I could do would be “frequently asked questions” where I would attempt to answer frequently asked questions that wouldn’t be on the topic of the site, and, what’s more, would be mostly rhetorical questions like “why do we hurt the ones we love” and so on. I gave up on this plan after I realised I couldn’t answer more than about two such questions. But here’s an answer to a question anyway. The question: why do we always look like criminals on our ID photos? I thought the answer was simple: it was because criminals look like normal people. What gives the “criminal look” isn’t something inherent – it’s that the photographs we see of criminals are mugshots and ID photos.
However, the answer is perhaps not as simple as that. Because it turns out we don’t all look like criminals in our ID photos. A study performed by Valla and coworkers at Cornell involves showing people pictures of 20-something males and having the subjects guess whether the pictures are of criminals, and, what’s more, what kind of criminals they are. Here is the PDF. Try to skip all the florid prose explaining how bravely un-PC they were to perform this study, and just go to the results. Keep in mind that the effect is quite small (well within standard deviation of guesses). It could be one of those “green jelly beans cause acne” things. I feel like saying this after every psych study, but if the effect is much smaller than the standard deviation, it means that the study basically found a fun fact whose effect on your life should definitely be: nothing. And, after all, if it was a sizeable effect, you could pick criminals out of police lineups. But nevertheless it exists. So, what this means is that at some level of aggreagation there is a pattern, and we don’t actually look like criminals on ID photos. I tried the dataset on myself and did slightly worse than 50%. So I guess another thing we learned here is: do not outsource your criminal recognition to me.