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FIGURE 2.11 Heatmap showing the aggregate dwell time of six participants who saw the baby monitors in this order (the order was counterbalanced across participants). The Graco package (third from the left) attracted the most initial attention.
In Search of the Simplest Solution
Once you have decided that eye tracking can in fact generate useful insight that will address your study objectives, you can move on to the second question in the to-track-or-not-to-track question set shown in Figure 2.1. Now is when you should determine if your research questions can be answered by methods simpler than eye tracking. Follow the principle of parsimony, which states to avoid unnecessary complexity and use the simplest possible solution.
Why is this step necessary? Adding eye tracking to a study means extra cost related to equipment, software, moderator training, additional time in the session, and additional preparation and analysis time. Traditional usability testing methods, including behavior observation and verbal protocol, are still quite effective, and are also less costly and less time-consuming.
Why Use a Microscope When a Magnifying Glass Is Enough?
Imagine a “quick-and-dirty” formative usability study aiming to assess the ease of use of a prototype website. You grab a few potential users, give them a few tasks, determine the key issues, and iterate the design. Adding eye tracking to your study might be unnecessary. Why use a microscope if what you are looking for can be detected with a simple magnifying glass (see Figure 2.12)?
Eye tracking tends to be more useful later in the design process, once the main wrinkles have been ironed out and much of the visual treatment has been finalized. It can benefit studies looking for answers to specific questions that arose from earlier testing and could not be properly addressed by previously used methods.
In summative studies that focus on user performance, eye movement measures will often correlate with other measures. However, adding eye tracking can be useful if you think the other measures may not be sensitive enough to detect what you want to be able to detect. The “Prescription Drug Labels” case study was a good example of this.
FIGURE 2.12 A magnifying glass is often sufficient for what you want to see.
When Eye Tracking Is the Simplest (or Only) Method
There are research questions that will always be best answered by eye tracking. These questions are related to attention capture and engagement, and include all those listed in the “Measuring Attraction-Related Differences” section earlier in this chapter. For example, when my team was asked to find out which location of the recipe labels on meat packaging made the labels most noticeable, there was no hesitation that eye tracking was the right method (see Figure 2.13). Data gathered through other channels, such as asking people what drew their attention and when, would have not been nearly as reliable because humans are not fully conscious of their attention focus.
FIGURE 2.13 One of the questions in this study pertained to the location of the recipe label: Would it be easier to notice when placed below the meat label (left photo) or diagonally across from it (right photo)?
Using Eye Tracking to Gain Stakeholders’ Buy-In
“Does my study need a buy-in boost?” is the third question that you should ask yourself when deciding whether or not to use eye tracking. There is a layer of mystery surrounding eye tracking. Anyone can watch what participants are doing and listen to what they are saying but specialized technology is required to see where they are looking. Because it is not simple or readily available, eye tracking seems more scientific and more interesting than conventional usability methods.
Therefore, eye tracking studies get more attention in organizations than “plain” usability studies. More stakeholders come to observe data collection, more read (or at least look through) the research report, and more attend the final presentation. It comes as no surprise that eye tracking often serves as a marketing tool for usability testing.
In addition to increasing the visibility of research in organizations, eye tracking helps convince stakeholders of usability issues. When presenting a problem that your usability study uncovered, your stakeholders may or may not take it seriously. Showing a gaze plot or gaze replay of a participant experiencing the confusion and inefficiency you just described suddenly makes the problem hard to ignore or refute (see Figure 2.14). This is exactly why participant quotes and video clips are included in reports and presentations—to back up the findings, as if to say, “I didn’t make this up, it really happened!” Eye tracking takes this evidence to the next level because eye movements are perceived as more objective than what people say or do.
However, just like it’s possible to write well-received deliverables and give successful presentations without participant quotes or video clips for added color or emphasis, eye tracking may simply not be necessary if you already have your stakeholders’ attention and buy-in.
For those who want to use eye tracking just to influence others, here is a word of caution. Your stakeholders may expect your study to result in unique eye tracking insight—something that they could not have learned only by using conventional methods. Instead of gaining their buy-in, you may disappoint them if your eye tracking data are mostly used to illustrate and support problems uncovered through traditional usability testing. Thus, setting clear expectations with stakeholders is key.
FIGURE 2.14 Even though this participant mentioned that he couldn’t find the store locator link because he didn’t notice the top navigation at first, showing his gaze plot or gaze video to stakeholders can help drive the point home.
Summary
• Avoid the “I want to know where people are looking” research objective because it doesn’t result in actionable findings. Use eye tracking only when it can provide insight to inform a design or business decision. Don’t use it just because the findings could be interesting.
• Eye tracking can benefit formative testing by improving design recommendations through:
• Detecting usability problems in the absence of other more conventional indicators such as participant behavior and feedback.
• Revealing the source
