Justin Briggs illustrates how search engine users pay attention to search results that include social annotations in his excellent post, How Does Google Authorship Impact CTR?
I pulled the following quote from his blog to put the accompanying heatmap in context:
“As you can see, the first result still pulls attention, but the annotation is pulling the user far down the page. It’s position 4 or 5 (depending on how you count) and it’s receiving significantly more fixation from the user than any other result. You can also see the click icon, showing the user ultimately picked this result.” Read the rest at Justin Briggs.