Eye tracking in Human Computer Interaction Studies
By Elizabeth East
In order the test products and websites for their usability, testers must decide between many different testing options. There’s the traditional usability test, focus groups, surveys, and heuristic evaluations. In these types of methods, there are typically few tools involves. The actual product being tested and then several cameras to record that testing process. One tool that can provide unique information about how the user is using their product is eye-tracking devices. These devices come in several different varieties and track where the users are looking when they are using the product or website.
There are several different types of eye-tracking devices. There is the eye-tracking bar, which can attaches to a computer monitor or tablet. But a lesser-known and utilized eye-tacking method is the eye tracking glasses. These gasses allow the user to move around while still producing data. It would be ideal for using with products that are not websites but would still benefit usability experts to know where are for how long, users are observing or using different parts of a website. These glasses also provide mobility to testing. Individuals could wear them throughout the day as they use a mobile product such a cell phone, tablet, or app. This mobility would provide valuable data that would be very difficult to recreate in the lab.
Older versions of eye-trackers work by capturing the point-of-regard using the corneal reflection/pupil-center method (Goldberg & Wichansky, 2003). This type of eye-tracker usually consists of an infrared camera attached to a computer monitor or tablet. This camera uses the infrared light to create a reflection of the eye to make the eye movements easier to track. New glasses work similarly; accept that the infrared camera is located on the inside of the glasses themselves, on the top inside corners of the glasses rim. Previously, eye tracking glasses were bulky and more of an annoyance to wear. Today, however, manufacturers are designing the glasses to be much more sleek, light, and less invasive to wear. These new eye tracking glasses are much more ideal for testing of mobile devices.
In practice, the eye-tracking glasses would be worn by the uses, either in the field or in a lab setting, while he or she uses the device, capturing eye movement and fixation information about the product being tested.
Eye tracking is useful to human-computer interaction study for several reasons. According to the “on top of the stack” theory in cognitive processes, where the moves to can provide meaning information about where that person’s attention is being directed to in relation the digital visual display. Eye tracker also provides information on eye fixations which are times when the eyes are relatively stationary while taking in or encoding information. Eye fixations provide information about how much processing power the user is giving to that particular piece of information (Goldberg & Kotval, 1999).
Knowing the attention and processing power users are using while operating devices or using apps can provide meaning insights to usability specialists. Where users are paying attention to can provide usability specialists with the insight they need for determining what parts of the device are confusing to users and which are pleasing to users. However, it is important to note that eye-tracking data is not always straightforward. At times, the eye-tracking data can be subjective: usability specialists will not know exactly why a user was paying more attention to some part of a device. Is because they are more interested in that section or are they confused and spending a lot of time and cognitive resources trying to figure out the meaning? Regardless, this can provide usability specialists with the information they need to ask the right questions to their users or investigate further.
Additionally, eye-tracking data could become even more useful when combined with other usability methods. Skin conductivity is a great method for collecting biometric data on what is the arousal state of the participant. Skin conductivity data coupled with eye tracking data and a simple questionnaire could provide usability specialists with a large amount of data on their product.
Examples of situations in which mobile eye-tracking glasses could be used would be:
- Rush hour traffic/ commuting: the glasses could be used to test how a potable device or app is used on a commuter train or bus.
- Testing cars in general
- Transportation consoles
- Testing plane cockpit displays
- Car consoles
- Digital supports in tablets for mobile products.
- Programs for doctors
- Factory managers
The eye-tracking devices could provide valuable information about how the product will be used in the environment in which it will actually be used in. In the real world, distractions are unavoidable and thus, knowing how some users would use a product amongst these distractions would be essential to design.
Goldberg, J.H., Wichancy, A.M. (2003). Eye tracking in usability evaluation: A practitioner’s guide. The mind’s eye: Cognitive and applied aspects of eye movement research, 493-516.
Goldberg, H.J., & Kotval, X. P. (1999). Computer interface evaluation using eye movements: Methods and constructs. International Journal of Industrial Ergonomics, 24, 631-645.
Ghaoli, C. (2005). Encyclopedia of human computer interaction (1st ed.). Hershey, USA: Idea Group Inc.