Via Gary Bernhardt, here's an interesting study on things that can make Python code hard to read:

http://arxiv.org/pdf/1304.5257.pdf

(I suggest trying the experiment yourself on Figure 1, before continuing on to read the explanation in the text - the result may surprise you!)

I've also followed up with the researchers regarding the experimental design for their vertical whitespace question - I think it has some flaws that limit its applicability in real world code, so perhaps I can interest them in getting another paper out of it :)

Cheers, Nick.

-- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia