From: http://behind-the-enemy-lines.blogspot.com/2008/03/mechanica... and http://asc-parc.blogspot.com/2008/07/mechanical-turk-demogra... 82% of turkers are from the US, Canada or the UK and over 75% have a Bachelor’s degree or higher.
People don't spend time on MT for the money. Ok, some people do, but I believe the overwhelming motivation is the same motivation behind casual gaming.
It's just a fun thing you do because you're bored and it's like a little internet scavenger hunt.
Most Turkers are from North America, IIRC. It's more about the cognitive surplus of western laborers versus their third-world counterparts, which is related to their earning power.
Edit: Not sure why your comment was getting downvoted. I voted it back up -- it's an insightful and appropriate comment!
Taking the time out from what you're doing to write down what you ate and how many calories it was incurs a lot of "transaction" costs. Its distracting.
However, if you're on your computer and are sitting there doing many of these one right after another its a lot faster and doesn't require changing your focus.
This is the exact same reason all time management books recommend answering emails in batches.
Any thoughts and any ways to get around this?
Actually, almost all forms of employment do so as well.
A rich, fat, lazy person snaps a picture of his lavish meal with a fancy iPhone, and rather than take a brief moment to ponder the calories, … uploads it for, not just one, but three other people to ponder and estimate the calories and report back. The most dissimilar answer is rejected; that person is not compensated.
This only works if there is a very large pool of very poor people who are willing to do these mundane tasks for (fractions of) pennies. These “workers” certainly can’t afford an iPhone; they probably can’t even afford the meal they are looking at.