Cornell University did an Eye tracking study with 20 students on how much they trust Google's positioning vs. their rational judgments. The results did not much change from previous studies except that when normally using a search engine, the students read the titles and abstracts for the first two search results, and then skimmed through the rest: “The first link was proportionally clicked more often,” said Prof. Thorsten Joachims, computer science, another co-author of the study.
The researchers also manipulated the search results in two ways. For some subjects, the first 10 results appeared in reverse order, with the tenth result showing up first, and for others, the first two results were swapped.
“Even in [those conditions], link number one still got the most clicks,” said Joachims.
Many students, however, had eye movements that indicated they suspected something was amiss. They spent an average of 10.9 seconds looking over the abstracts when they appeared in the reverse order, compared to 6.5 seconds when they appeared in their normal order and 5.8 seconds when the first two results were swapped."