Just like doctors need to pay close attention when patients describe their illness, and do various medical tests to validate those symptoms and come up with their diagnoses and prescriptions, usability professionals, in a sense, are doctors too. They are “examining” users when they are interacting with products, so as to diagnose the problematic issues (“illness”) in design.

Since a lot of usability methodologies (interviews, focus groups, etc.) heavily rely on users’ self-reporting, if users don’t (or are not able to) truly describe their experience with products, in other words, if users either intentionally or unintentionally lie about their experience, it would largely bias the usability diagnosis. Instead of self-reporting, are there any behavior-based “tests” that would help us directly gain insights based on how users do and/or react to products?

Eye tracking might be an option. Eye tracking can simply be described as “a technology to track where people’s eyes are looking.” Although it is being used more frequently in user experience research and marketing, years ago, when people being tracked needed to wear a special type of contact lenses or wear a heavy head-mounted device, eye tracking was only used for science research purposes, and needed to be operated by people with eye-tracking domain knowledge.

So do users’ eyes lie about their behavior? In the 1980s, one of the most influential theories in the field of eye tracking was raised by Just and Carpenter: the “mind-eye hypothesis.” According to the hypothesis, what is fixated (by eyes) and what is processed (by brains) are usually coupled together. So when users look at a word or object, he or she also thinks about the process (cognitively). Therefore, researchers can use the eye data to infer what content on an interface attracts users’ attention and has been cognitively processed by them.

With the development of infrared eye tracking technology, in today’s eye tracking study, there’s no need for users to wear any special equipment, the eye tracker is often built in with the computer monitor. By simply viewing content shown on the monitor, the built-in eye tracker is able to track the eye movement with an accuracy of .01 second! The difficulty of eye tracking more and more falls into the study design and the data analysis stage. First of all, not all usability issues can be diagnosed by eye tracking. A few issues that eye tracking can help identifying are: the visibility of a UI (e.g. do users pay attention to a specific part of a product or a website), users’ efficiency (e.g. how long do users spend on each step of a task, which step is particularly time-consuming to users? any distracting content?), users’ attention pattern (e.g. where do users’ eyes go on this particular interface? where is the best location to put the product name?), etc.

Knowing what are the right research questions to ask, and what are the appropriate visual stimuli to pick in order to design an eye tracking study might require that researchers have relevant eye tracking experience. Additionally, even a short 10-minute eye tracking test can generate a multitude of fixation, saccade, and scanpath data. How to reduce, reformat, and analyze the data requires usability specialists to understand the data both from a high-level perspective (to identify potential metrics that might help to answer the research questions) and from a micro-level perspective (to identify potential areas of improvement by looking at differences at second or mini-second level). To generate a general heatmap might take 5 seconds, but if you want to tell a full story based on users’ eye movements, it might take months. Eye tracking is still a relatively new toy for usability professionals (or “doctors” 🙂 ). As with any other methodology, it’s by no means a panacea. Often times it is coupled with Retrospective Think Aloud protocol, that is, users will be asked to view their scanpath afterwards to describe the reasoning behind the way they visually interact with an interface.

The field of eye tracking is exciting and promising, not only because it captures a new aspect of user behavior, but also because it might help to explore a brand new and different way of human-computer interaction. Tobii, one of the leading eye tracker manufacturers in the world recently devised an eye tracker built-in laptop that enables users to use their eyes to perform different actions just like how we are using the mouse with our hands.