Peter Da Vanzo spotted Google asking users if they found a link useful:

Note: It was only shown after he clicked on the result and then returned to the search results page.

This is similar to our free feedback tool that asks if the search results page was useful. The main difference is they’re asking about one search result rather than all of the results. We provide the feedback tool as one way of measuring search quality.

We normally assume that if someone returns to the search results page after a short time then they didn’t find the link useful and in our Learning Search we put less weight on those clicks. This type of survey could be a way of testing that assumption. I would expect Google would see the proportion of clicks on the Yes button rise as a function of the amount of time they spent at the link.