environment can grab your attention, too.
If bottom-up factors were the only ones influencing people’s attention, everyone would look at the world in the same way, regardless of what they knew and what they were trying to accomplish. This consistency would certainly make your research easier, wouldn’t it? Studying different user groups and multiple tasks would no longer be necessary.
Unfortunately (but also more interestingly), this is not the case, due to the involvement of top-down factors. Top-down attention is knowledgedriven and relies on your previous experience and expectations. You intentionally choose to look at information that you consider relevant to your goals.
You have probably already heard that eye movements are task-dependent. What this means is the same person will look at the same object differently if given a different task. For example, someone looking at mobile phone packaging will generate a different gaze pattern when trying to determine the brand of the phone than when trying to find out if the phone will allow him to browse the Web (see Figure 1.8). It is the top-down attention that is responsible for these differences.
FIGURE 1.8 Left: Gaze plot of a person looking for the brand of the phone. Right: Gaze plot of the same person trying to find out if the phone offers Internet access. Notice how the same person with the same package—but a different task—produced different fixation patterns.
Applications for Eye Tracking
There are two main applications for eye tracking: as a research technique and an input device. As an input device, eye movements become control signals for a computer system, either instead of or in addition to a mouse and keyboard. People with disabilities such as ALS and cerebral palsy use gaze-controlled applications to help them communicate. Gaze interaction is also used in entertainment (for example, gaming) and is making its way into mainstream mobile applications.
The rest of this book focuses on how eye tracking can be applied to research, specifically UX research—an investigation of how people experience products, interfaces, services, or even their surroundings. UX research can be divided along two dimensions: the target of the research and the scope of the research (see Table 1.1). This breakdown results in four categories: Engineering Psychology Research, Design Research, User Research, and Design Evaluation. Eye tracking can be used in all four types of research, but this book is primarily about eye tracking for formative (or diagnostic) and summative design evaluation (the shaded bottom-right quadrant of the table).
TABLE 1.1 BREAKDOWN OF UX RESEARCH
| Target of the Research | ||
| Scope of the Research | ||
| Users | Design | |
| Generalizable across products | Engineering Psychology Research | Design Research |
| (theory-driven and often academic) | Goal: To understand the capabilities and limitations of human perception, cognition, and movement control. Sample research questions: What is the effect of noise on human performance? What factors impact how well people can switch between different tasks? How do visual scan strategies of expert pilots differ from those of novice pilots? | Goal: To understand how design types or elements impact the user experience. Sample research questions: Which layout for an online form is most efficient? How do people view search results pages? Do icon labels improve user performance? |
| Productspecific (atheoretical and doesn’t generalize beyond one product) | User Research Goal: To learn more about the needs, preferences, motivations, and processes of the users or potential users of a particular product. Sample research questions: What are the current practices and preferences of patients learning to use a selfinjection device? Why do users of a particular mobile phone go to the customer support website and does the site meet their needs? | Design Evaluation Goal: To evaluate a particular product based on the user experience it creates. Sample research questions: How can this product be improved to provide a better user experience? (formative research) How does the new interface compare to the old one? (summative research) |
Tool or Method?
When I was learning how to drive, a friend took me to a large parking lot by a mall. It was a late evening, so the lot was almost empty. There he taught me how to start and stop the car, how to speed up, slow down, steer, and use the turn signal and mirrors. By the end of the night, I was pretty good at it. However, before I could take my Dodge Intrepid on real streets (and unleash its true potential), I had to learn how to drive according to the rules of the road, both written and unwritten.
By the same token, just because you can operate an eye tracker does not mean you can or should use eye tracking in your research. Knowing how to turn on the system and where to click to start a recording or obtain a heatmap is not sufficient (see Figure 1.9). You need to know how to apply eye tracking in a way that yields valid and useful insights. This knowledge encompasses planning, preparing, and conducting studies, as well as analyzing and interpreting the collected eye tracking data. Without a sound method, you are in danger of producing meaningless information and attractive but likely misleading visualizations.
FIGURE 1.9 A heatmap is a commonly used (and misused) eye tracking data visualization. It represents the values of a variable (for example, gaze duration) as colors, where the amount of “heat” is proportional to the level of the represented variable.
When you think about eye tracking, you should consider both the tool— the eye tracker—and the methods that allow you to put the tool to good use. Learning how to operate the tool is not difficult because modern eye trackers are much easier to use than those manufactured even a couple of decades ago. Each eye tracker is accompanied by a detailed manual, and additional training is often provided by the manufacturer.
Information on methods, on the other hand, is not as readily accessible. There are several articles and book chapters available, but no one source that consolidates all the knowledge. What motivated me to write this book was the high demand for sound eye tracking methods specific to the field of user experience. But before we get to the methods, let’s first discuss how to decide whether or not to use eye tracking in the first place. And that’s
