From the Wall Street Journal:
What is it about a Web site that might make it literally irresistible? Clues are offered by research conducted by Irving Biederman, a neuroscientist at the University of Southern California, who is interested in the evolutionary and biological basis of the human need for information....
...coming across what Dr. Biederman calls new and richly interpretable information triggers a chemical reaction that makes us feel good, which in turn causes us to seek out even more of it. The reverse is true as well: We want to avoid not getting those hits because, for one, we are so averse to boredom.
It is something we seem hard-wired to do, says Dr. Biederman. When you find new information, you get an opioid hit, and we are junkies for those. You might call us 'infovores.' "
Now we know!