What is eye tracking?
Eye-tracking systems detect and record where a participant’s eyes are focused at any given point in time. Eye-tracking records bothfixations and saccades. Fixations are the brief pauses the eye makes in order to take in detailed information. Saccades are the very fast jumps the eye makes between fixations.
Recently, eye tracking equipment has become very unobtrusive, often to the point that a casual observer may not even notice the equipment at all. Most commonly, infrared or near-infrared light is reflected from the participant’s eyes and that light is detected by an optical sensor. In the past, head movement was a problem when recording eye-tracking data, so many systems restricted participants’ head movements by bite bars or chin rests. This is no longer the case as eye-tracking systems have become much more sophisticated about compensating for head movements. This means that participants can behave as naturally as possible while in the lab.
How can eye-tracking help you design a better website or product?
Eye-tracking data lets us see what users look at, for how long, and in what order. Eye-tracking data supplements the other user experience data that we are already collecting in a traditional usability study.
It can help us gain insights that we otherwise would not have access to. For example, in a traditional usability study, we can observe if someone clicks on a target link fairly easily, however if he or she does not click on it, we are left with a number of questions:
- Did the participant see the link, but did not click it because it didn’t seem like the right thing to click?
- Did the participant not even see the link?
- If they didn’t even look at the link, where did they look instead? (Where do they expect to find the appropriate link or button?)
- Is something in the visual design distracting the participant from the main task?
The eye-tracking data provides objective answers to these questions and helps us determine if the target link might be labeled incorrectly, is in the wrong place (and if so, what is a better place for it), or is simply surrounded by too much “visual noise.”
When coupled with the participants’ verbal feedback and careful observation of their actions while using the product, knowing where a person looked while completing a task can also help us understand:
- What attracts the user’s attention and what doesn’t
- How efficiently (or inefficiently) the design leads the participant to achieve their goals
- Which of two design variations is more effective
- What content is being read in detail, what content is being scanned, and what content is being completely ignored
Are there any drawbacks?
As with all user experience research methods, there are some limitations. First, as mentioned at the outset, eye-tracking primarily records the user’s fixations. A fixation relies on our central vision, which is the kind of vision that allows the brain to take in and process detailed information. As anyone who drives a car knows, we also use our peripheral vision to detect changes in the visual scene, to detect motion, and to determine where to fixate our eyes next. This means that human beings “see” much more than they fixate on. The converse of that is also true. Simply because a person fixates on something doesn’t necessarily mean that they have consciously processed or comprehended that item. Think about the last time you were looking for lost car keys and they were right there in front of you the whole time. You know you fixated on those keys numerous times, but did you actually “see” them? Probably not.
Another limitation is that eye-tracking data will not answer all of our user experience research questions. It is best suited to research questions around the findability of UI elements or questions of visual and spatial design in general. Most questions about overall process flow, information architecture, and taxonomy are better answered using other methods.