Have you ever discovered a bug in an app and then started seeing it everywhere? It's not magic or a developer conspiracy. It's the selective observation effect: your brain, upon detecting something annoying or striking, registers it more intensely and begins to filter it into your reality. The actual frequency of the problem hasn't changed, but your perception tells you otherwise. 🧠
How this bias affects software testing 🛠️
In development, this bias is a silent enemy. When a tester finds a specific bug, their attention focuses on similar patterns, ignoring other areas. The result: more incidents of the same type are reported, even though their occurrence is stable. Teams can misinterpret the data, thinking a bug has spiked, when only its mental visibility has increased. To avoid this, it's best to use objective metrics and rotate review tasks.
The day I saw a bug even in my soup 🍜
Once, after debugging a rendering error, I started seeing dead pixels on my monitor, on my phone, and even on the sign at the fruit shop. I called the greengrocer to report the bug on his sign. He gave me a strange look, sold me some apples, and said: that's a burned-out LED, not a bug in your code. Since then, when I see an error, I take a deep breath and think: is it real, or is my brain working overtime?