What is the distribution of clicks on a search engine results page? What percentage of clicks gets each search result according to its rank? How much more usersâ€™ attention gets the first listing compared to the second? Or how often do users click the listing below the page fold? The way users interact with SERPs is one of the most frequently discussed topics in the SEO community and is also a very important field of study for the search engine specialists. To answer the above questions researchers employ the so-called eye tracking experiments.
The objective of eye tracking studies is gaining insight into how users browse the presented abstracts and select links to click. The results of eye tracking research provide Internet marketers with information on clickthrough rates, thus allowing them to make correct predictions on traffic changes as their rankings are gained or lost. For SE engineers the results provide a basis for improving the interfaces of search engines and metrics to evaluate the relevancy of the presented search results.
To detect usersâ€™ interaction patterns the eye tracking experiment observes a number of indicators of ocular behavior using a CCD (charged couple device) camera similar to the appliance used to read bar codes. The indices of ocular behavior include eye fixations, saccades, scan paths and pupil dilation. Eye fixations are defined as a stable gaze lasting for 200-300 milliseconds representing visual attention to a specific area of a SERP. Pupil dilations or pupil diameter changes represent a measurement of interest in a particular listing. This variable is especially important as it helps interpreting an implicit user feedback to the relevancy of the presented search results.
Cornell University Eye-Tracking Analysis of SE Users’ Behavior
One of the most recent eye tracking studies was performed at Cornell University by Laura A. Granka, Thorsten Joachims and Geri Cay (). They used a sample of undergraduate students instructed to perform search in Google for 397 queries o topics covering movies, travel, music, politics, local and trivia. This study has produced the following results.
Fig 1. Google SEPR Click and Attention distribution ‘heat-map’
Study Results: Clicks and Attention Distribution
As you can see from the graph below and a SERP â€˜heat-mapâ€™ based on it, the first two listings capture over a half of the userâ€™s attention in terms of time of the eye fixation. Whereas the attention is shared almost equally, the difference in number of click between the first two listings is much more surprising: over four times! After the second listing the eye fixation drops sharply. Search results number 6 to 10 receive roughly equal attention. Here an interesting thing is that the 7th listing gets less attention than the succeeding 8th â€“ apparently here we can observe the effect of the page fold. The 7th listing is just below the screen edge and is often skipped as users scroll the page down to the bottom (during the study the 7th listing was clicked only once). On the graph you can also see the 11th listing from the second page of the search results. It gets only about 1 percent of clicks and user attention â€“ 2.5 times less than the lowest ranked result on the page one.
Fig 2. Time spent on viewing each results compared to the number of clicks. Source 
Often people consider getting to the â€˜top-tenâ€™ of Google as a measurement of the SEO success. Evidently this is a rather rough approximation. The â€˜top-tenâ€™ itself is a very diverse group with the number of clicks increasing almost logarithmically as your rank grows. For instance, the first five positions get over 88% of the traffic, and the first three â€“ 79%.
SERP Browsing Patterns
Another important result of this study is the discovery of the browsing pattern: the way people read a SEPR. To assess the performance of the search algorithm it is vital to know how users evaluate the presented abstracts before clicking one of them. For example, if a user clicks the third listing, did he look the abstracts above and below it? The following figure shows how many results above and below of the selected listing are scanned on average.
Fig.3 Number of results scanned above and below the selected abstract. Source 
The effect of the page fold is clearly demonstrated here as well. While the first 5 listings are clicked after browsing through 1 to 2.68 listings above and below, the 7th listing is clicked after the entire page is examined! The listings below the page fold (8-10) are clicked after the first five or four listings are scanned. You can also see that the number of listings scanned above the clicked result is much bigger than the number of listings below. This indicates that users browse the list from top to bottom.
To Sum Up
While the study deals only with the first page of the organic search results, it can be assumed that similar results can be produced for other pages and perhaps even for the list of the paid ads in the right sidebar.
In addition to the academic researches there is a number of companies producing eye-tracking studies for the commercial use. The most notable of them are Eyetools.com and Poynterextra (http://www.poynterextra.org/EYETRACK2004/index.htm)
1. Laura A. Granka, Thorsten Joachims, Geri Gay. ‘Eye-tracking analysis of user behavior in WWW search’, SIGIR, 2004. Available at http://www.cs.cornell.edu/People/tj/publications/granka_etal_04a.pdf Retrieved on 26.10.06
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