Live coding interviews measure stress, not coding skills

Summary

Some people enjoy live coding interviews. I’m not one of them.Two days ago, I stumbled upon a post on LinkedIn:Sounds absurd at first. Why would a senior engineer, who has been writing code for years, struggle with something as simple as a basic algorithm? Did they suddenly forget how to code? Maybe. But I have a different perspective.A quick story #Four years ago, I applied for Toptal. I passed the initial stage(s). I passed a 90-minute Codility assessment (three problems as I recall it). Then, I failed to finish a live coding test for a full 30 minutes (more or less, I don’t remember exactly). I revisited the test a few hours later, and I solved the problem in no time.That was super confusing. The problem wasn’t that hard really. I was able to solve it, but failed to do so in the live coding session.This triggered my curiosity, and I did some research back then. Turns out it’s a well-known phenomenon in the scientific literature. It’s all about stress.Your brain under stress #When you’re placed in a high-stakes, time-pressured situation, like live coding, your brain reacts exactly like it would to any other threat. The amygdala gets activated. Cortisol levels spike. Your prefrontal cortex, the part of the brain responsible for complex reasoning and working memory, gets impaired. Either mildly, moderately, or severely, depending on the individual and their baseline stress resilience.Working memory is the most reliable proxy (I know of) for fluid intelligence, your ability to reason, solve novel problems, and think abstractly. It’s what you mostly need to pass live coding tests, I believe. When your prefrontal cortex is impaired due to stress, your working memory capacity shrinks.For some people, especially those with even mild performance anxiety, it becomes nearly impossible to think clearly. Your attention narrows. You can’t hold multiple steps in your head. You forget what you just typed a few seconds ago. It feels like your IQ dropped by 30 points. In fact, it ...