I would guess they pay more attention to what works and what doesn't than to psychological theory or conjecture. It's easy for anyone to monitor what kind of ads perform better than others, and since ads are much of Yahoo's bread and butter, you can be sure they are paying attention.
I agree. So I should rephrase my question. Do these ads really perform better than footnote ads? I wouldn't be surprised if the higher clickthroughs are accidental (which, I am sure they measure for).
