As remarked on in the linked blog post, there seems a nontrivial likelihood that the effect is related only to visual processing, not general cognition. While Chatham hedges the visual processing idea a bit, I find it a more persuasive hypothesis than the other options. I can't really give this much weight unless it were demonstrated to have a similar effect on non-visual cognitive tasks.

On the other hand, if this is signicant I may need to take up reverse-pacing.