I’m always annoyed by the arrow length trick. This article calls it the “Müller-Lyer” illusion. The problem is inconsistent line caps and the joints overlapping

I’m always annoyed by the arrow length trick. This article calls it the “Müller-Lyer” illusion. The problem is inconsistent line caps and the joints overlapping means that the size of the line actually is changing a little. As a result, I’m not sure whether there’s an optical illusion involved or not, and, if there is, this is a poor way of demonstrating it.