Okay, so it's absolutely anecdotal evidence, but my cat, Kisa, (sorry, no obligatory cute photos up (yet...)) is a fair judge of interface affordances. She's recently discovered the computer screen, and loves to tap at it with her paw (there's a case for direct interactivity instead of using a keyboard and mouse!).

Anyhow, cute as that is, the interesting bit is what she taps on. Basically, she loves the cursor (naturally, it's small and moves fast) but she'll also tap on icons (like the top navbar), and solitary beveled buttons, but never other interface elements like imagemaps or text links.

As obvious and rational as this may sound, it's still important to remember that there is a very real difference between inhierent affordances that come from within (low, sturdy flat things can be sat upon) and experiential, learned affordances (chairs can be sat upon).

While text links are the strongest experiential affordance we have on the web, other ones, like non iconographic imagemaps, or worse yet, navigation methods whihc require text ("Click on the country you're currently in') require forebrain thought. People designing for the web should try to reserve the forebrain to the content, and not the navigation.

At any rate, it's clear Kisa needs her own laptop now.