Pros and Cons of Eye Tracking

Eye tracking, as the name suggests, is the process of tracking eye movements to see what people are looking at. It’s used on websites, applications and software products to get additional insight into what people are focusing their attention on. Some feel that eye tracking is a useful addition to the user testing process while others feel that the limitations of eye tracking outweigh its value.

Eye tracking device

A typical eye tracking device

A brief history

The first recorded instance of eye tracking took place in 1879 in Paris, where ophthalmologist (eye specialist) Louis Émile Javal observed that reading does not involve a smooth sweeping of the eyes along the text but a series of short stops and quick saccades. This changed the way people thought about how to lay out content and perhaps was the start of the more scannable pages of text that are common today.

Following him Edmund Huey was the first person to build an eye tracking device. This terrifying sounding contraption was a sort of contact lens with a hole in it. The device was connected to a pointer that moved in response to eye movement.

Alfred L. Yarbus made some important discoveries in the field in the 1950s, discovering a connection between his subjects thought processes and their eye movements stating that:

“Records of eye movements show that the observer’s attention is usually held only by certain elements of the picture…. Eye movement reflects the human thought processes; so the observer’s thought may be followed to some extent from records of eye movement (the thought accompanying the examination of the particular object). It is easy to determine from these records which elements attract the observer’s eye (and, consequently, his thought), in what order, and how often.”

In the 1970s, eye tracking research expanded rapidly, before in the 1980s, the link between what people were thinking and what they were looking at was questioned. With the advent of computers eye tracking tool became more sophisticated and research continued.

These days eye tracking is no longer only a tool for high-level scientific research and is increasingly used by marketing companies and web agencies.

Mistakes to avoid

On the face of it eye tracking sounds great. You can see where users are looking without them having to tell you, giving valuable insight into where they are focussing their attention. However, there are some potential issues with using eye tracking devices that need to be avoided.

Clockwork Orange eye test

Make sure your users are comfortable during any tests!

Using expert analysis and facilitation, one can avoid many of the drawbacks associated with eye tracking. Those with experience are able to take into account the limitations of the software and hardware and bridge the gaps in data and reach meaningful insights to compliment other forms of testing.

  • Some of the limitations industry professionals have outlined include:
  • Accuracy is typically to nearest centimetre, not millimetres
  • Tests cannot measure peripheral vision
  • Test environment can mean less natural subject behaviour
  • Gaze does not necessarily equate to understanding
  • Does not work on users with glasses or those wearing a lot of mascara
  • Requires more users than other forms of user tests in order to quantify reliable results.

Most of these issues can be overcome but they need to be kept in consideration throughout the planning and testing process.


With so many potential drawbacks to eye testing it only seems reasonable to question whether it’s a technique that’s worth using at all. If used in the correct way though eye tracking gives a unique insight into an area of user behaviour that we would otherwise know nothing about.

There have been some high profile examples of eye tracking in the past that have shown user behaviours that we would otherwise know nothing about. The most famous of these is probably the ‘F-shaped’ reading pattern of users that was uncovered by Jacob Nielson.

F Pattern

People read web pages in a ‘F’ shape

On a smaller scale eye tracking can be used to give you qualitative results from small groups of users. Seeing the patterns of a user’s gaze may help give a better indication of where they’re looking and when. If you have a key message that you want to get across to people on a webpage then you need to ensure that this is in a position that people look at first, not one which they glance at after several seconds.

Even if you are confident that your design is the right one, and that it enables users to focus on the key areas quickly, an eye tracking study may help confirm this. This means it will not only give you more confidence in your design but also gives you evidence that you can share with stakeholders to further back up your decisions.

As with most analytical practices segmentation can help you get clearer more detailed results. Our testing process means we can segment testers by age and gender to see key differences in how people view your site, app or design. This will be particularly useful if you’re looking to target a particular demographic and you want to know if your design is going to work well for them.

Eye tracking can also be run on static designs. This is not always possible with other analytical tools that generate heatmaps based on mouse movement and scrolling. This means that testing can be run at various points in the design process to get a better idea on the optimum layout for pages.


As long as eye tracking is used alongside other UX methods and not relied on too heavily then there’s no reason why it can’t be a very useful addition to the testing process. The key here is expert facilitation and analysis to ensure that the tests are well run and that the results are not misleading. Eye tracking is not much use on its own but as an addition to more traditional user testing there can be a place for it in the overall UX process.


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