2 is all about.
Summary
• Eye tracking is the process of determining where someone is looking. It can also measure the characteristics of eye movements and of the eye itself.
• Eye tracking is usually conducted with the help of a device called an eye tracker. Most commercial eye trackers work by emitting near-infrared light to determine gaze location based on the relative position of the pupil center and corneal reflection.
• Human eyes jump from place to place a few times per second. The purpose of these jumps, also known as saccades, is to bring visual stimuli into the fovea (a small area of the highest visual acuity on the retina) and thus into focus. Information is extracted during fixations, which are short pauses in-between the saccades.
• Foveal vision spans only the central two degrees of the visual field. The farther away from the fovea, the more blurry and colorless the image becomes.
• Even though eye tracking only captures foveal vision (what we are fixating/focusing on directly), it provides useful information about visual attention because, in most cases, fixation coincides with attention.
• Saccade destinations (i.e., where the next fixation is going to occur) are selected based on a combination of bottom-up and top-down cognitive processes. In other words, where you look depends on the properties of what you are looking at, as well as your goals, experiences, and expectations.
• This book focuses on the application of eye tracking for UX research (design evaluation in particular) rather than for human-computer interaction. Both the device and method aspects of eye tracking are discussed, with a special emphasis on the methods, which help put the eye tracking devices to good use, leading to valid and useful results.
CHAPTER 2
To Track or Not to Track
Qualitative Insight: Detecting and Explaining Usability Issues
Quantitative Insight: Measuring Differences
In Search of the Simplest Solution
Using Eye Tracking to Gain Stakeholders’ Buy-In
Many UX practitioners seem to be divided into two opposing camps: those who are pro eye tracking, and those who are against it. The proponents seem to want to use eye tracking for every study, regardless of its objectives. The opponents, on the other hand, claim that eye tracking is just “smoke and mirrors” and does not have much value. As is generally the case, the truth lies somewhere in the middle. Eye tracking can be a valuable addition to some UX research and ineffective, or even wasteful, in other cases.
The Three Questions
The decision about whether or not eye tracking is appropriate for a study boils down to three questions. Figure 2.1 illustrates the process I go through when considering eye tracking as a method for a study. Typically, this is an implicit exercise unless I have to explain to the stakeholders why using eye tracking is or isn’t a good idea.
FIGURE 2.1 A set of questions to determine whether or not eye tracking is a suitable method for a research study.
The first and most important question is “Will eye tracking generate actionable insight that addresses my study objectives?” This is not to be mistaken for “Will eye tracking tell me something I don’t know?” Eye tracking will almost always reveal something new and perhaps even interesting, which is undoubtedly tempting. However, that insight may not be able to inform any decisions that have to be made based on the research findings. To justify using eye tracking in your study, your answer to the first question should be “yes.” But that’s not enough. There are two more questions, and you need at least one more “yes” to proceed.
The second question encourages the researcher to reflect on the economy of the selected approach: “Is eye tracking the simplest method that would answer my study questions?” If other, more conventional research methods (e.g., observation and user interview) can answer the study questions (which is, in fact, often the case), the use of eye tracking may be unjustified.
The third and last question, “Does my study need a buy-in boost?” should resonate with many UX researchers. You can’t make a difference if you don’t have others on your side, and that sometimes requires adding “color” and perceived credibility to your results. Even if the answer to the second question is “no,” a “yes” to this one gives you the green light, as long as the first question is a “yes” (meaning you have made sure that actionable insight will result from eye tracking).
Actionable Eye Tracking
When eye tracking proponents state reasons for using eye tracking, they frequently frame them as “Here is what eye tracking can tell us.” For example, “Eye tracking can tell us about users’ search strategies and decision-making processes” or “Eye tracking can determine what users find interesting.” These statements are not incorrect. However, they are vague and not very helpful to those trying to figure out when to use eye tracking in their studies.
Does it matter that you can identify a visual strategy employed by users to find the correct drug among others (see Figure 2.2)? Or that you can find out how interesting each area of a Web page is? While it is certainly true that some UX research (especially the more academic research) aims to explore how people interact with products and interfaces in general, as UX practitioners, we must often focus on gathering actionable information. We conduct research to inform decisions. “How can we improve this product?” or “Is this product ‘good enough’ to be launched?” are the high-level questions that our studies typically have to answer. Eye tracking can provide copious information, but most of it may never be useful for answering these kinds of practical questions.
FIGURE 2.2 You could collect and analyze eye movement data from pharmacists looking at drug labels when filling
