I can't stop thinking about curiosity rewards and how interesting the whole concept is. It seems like such a fundamental component of mental development. I can't wait to implement the more powerful model in Verve and run some experiments.
I just came across this article (referring to an article in the latest issue of American Scientist, which I couldn't find) describing some recent biological evidence of a sort of curiosity reward system: http://www.physorg.com/news70030587.html
The original (not free) article is in American Scientist... here is the first paragraph and a good diagram: http://www.americanscientist.org/template/AssetDetail/assetid/50770
Evidently, there is a "25-year-old finding that mu-opioid receptors – binding sites for natural opiates – increase in density along the ventral visual pathway..." These receptors are said to be involved in pain/pleasure processing elsewhere. Based on this evidence, Irving Biederman ran experiments using fMRI on humans viewing various types of images. "Biederman also found that repeated viewing of an attractive image lessened both the rating of pleasure and the activity in the opioid-rich areas."
It seems that the evidence described here might correspond to the more powerful model of curiosity, which says that curiosity rewards are proportional to the reduction in novelty. So, once the stimulus is fully predicted (and no longer novel), the rewards will disappear.
Here is another good quote: "The brain's craving for a fix motivates humans to maximize the rate at which they absorb knowledge."