Cats 'exploit' humans by purring; apparently there is a particular sort of purr - or tone that can be put in a purr - that motivates humans to get moving and fill the food bowl because it's just that annoying. It's plausible, considering the "soliciting purr" does have similarities in frequency to a baby crying... and anyone that's heard a baby cry knows that it's one of the most annoying sounds in the world, and we're just biologically programmed to do whatever it takes to make the awful noise stop. From the paper itself:
Embedded within the naturally low-pitched purr, we found a high frequency voiced component, reminiscent of a cry or meow, that was crucial in determining urgency and pleasantness ratings.
Now that is interesting. It's even more interesting that it may well be a learned behavior, though that makes sense as well. Cats are quick to learn anything if it means they'll get food or a treat. Meow in mom's ear in the morning? Gets your thrown off the bed. Purr in the world's most annoying fashion? Normally mom's fair enough that a purr won't make her mad.
I actually don't think I've got personal experience with this "soliciting purr," probably because I've got both my boys on a gravity feeder. Which would explain why they're both chubbing up. In the future I may have to switch to rationing their food, so we'll see if I get to hear the annoying uber-purr then. As things stand right now, when my bad kitty (Loki) wants me to get up, he does it by throwing things off the shelves, on to the floor. Or licking my eyelids. (I'm not making it up.) I think a manipulative purr would definitely be preferable.