TheOptimizationIdiot - 2:58 pm on Apr 16, 2013 (gmt 0)
Google would have to keep track of what the visitor continues to do (ie if he goes back to search from your page and searches for the same thing again) to even start to figure out if the visitor behavior is positive or negative for the site.
Oh, rest assured they do. You can't have personalization without that type of tracking, but results are becoming much more personalized even for those not logged in.
They definitely know if a visitor went back to the SERPs or searched for something related again. And what % of people who find your page do the same thing. And how that compares to what those same people do after visiting other pages in the same results. And probably a bunch more I'm not thinking to list off the top of my head.