For a long time, proponents of eye-tracking have said that the amount of viewing a link receives directly effects its likelihood of being clicked.  Well, it turns out that this is particularly true in the case of search results.  Recently, Eyetools and Sendtec released a study showing that decreased viewing on a search results page has a huge impact on click-through conversions . This is true for both paid and organic listings. 

For example, the data shows that if overall viewing of a link falls from 80% to 60%, the initial probability that the user will select the link decreases by over 50%! This helps to explain why even small drops in page position for organic search links has such a significant impact on a site's conversion rate. 

In addition to emphasizing the need for ads and organic listings to have high page positions, this result also means optimizing link performance is critical since not everyone can be a top organic or adwords listing. 

I've included the excerpt below in the hopes that it will open a dialogue about the effect of increased viewing for other kinds of web pages. 

The graph shows an important correlation between increased link viewing and the probability of being clicked. [...] The page elements which received the most clicks were those seen by the most users.  As user viewing decreased, so did the number of clicks.  [... Our data shows that] decreases in viewing will have a disproportionately large negative impact on click-through.

A number of other studies have explored various factors which influence a user’s decision to click including link text, description, and perceived link relevance. Our study shows that percent user viewing can be an excellent predictor of user click behavior for online searches.  Our study supports the logic that users must first see a link before they can make selections based on text descriptions or relevance. There are many factors which contribute to whether or not a user decides to select a link, but all things considered, eye tracking data is a reliable and efficient way of understanding why people do and do not click.

It is important to note that this data is specific to search results and should not be used in conversation about standard web pages. Eyetracking has proven to be very helpful in directing redesigns of web pages, landing pages, and emails with great increases in conversion rates, but this data presented here is specific to search result pages and should not be generalized to other pages.

Update, June 2010: Sadly, it seems that we outlived SendTec, our partner on this project. It appears that they closed down, taking the report down with the rest of their website.