Recently our Hamburg User Experience Roundtable took place at the offices of the local market research and usability evaluation institute, SirValUse. Our hosts were happy to give an impressive and well-founded talk on one of the techniques they’re using – eye tracking (you can download the slides here – sorry, they are in German). As most of you will know, eye tracking is a technique used to track a subject’s focal point on a given visual stimulus.
It is assumed (and highly probable) that the focal area is also the area of (visual) attention and that properties of the stimulus in the focal areas are perceived, cognitively processed, and more or less consciously interpreted. When the focal areas are plotted over time, so called “heat maps” can be created that give insight on which areas on the stimulus seem to attract the users’ attention and thus are processed best. Now comes the interesting part: It is also assumed that the more attention an area gets, the higher the probability that the user sees, understands and acts upon a given property of the stimulus. So, for a screen design, if a given function is placed in a presumably hot area and that area stays hot during the re-test, everybody is happy.
This is something I don’t understand. For me, there is no direct connection between eye tracking (i.e., visual attention) and user action. Attention in itself is free of value, it is neither positive nor negative. The processing and the interpretation are the important things about stimuli. The fact that users see something doesn’t mean they will click on this thing, perform their tasks faster, or enjoy a better user experience. True, eye tracking can be used to see whether a given ad diverts the users from the content, or whether a certain link is in an area that’s likely to be scanned at all. But on the whole, visual attention just provides the data necessary for a user to decide on further activity. Thus, for me, eye tracking is a technique that can be used to maybe support a usability test or an expert review, but it’s not a usability evaluation method in itself – it’s great for research, and the result should be collected and made available in big books on human perception (just recently, Jakob Nielsen published a new eye tracking-based study in his Alertbox that is basically this kind of fundamental research). My colleague and friend Frank Ollermann, University of Osnabrueck, supports this point:
Basically this is about objectively assessing visual attention. No other technique can assess visual attention in such a timely accurate manner as error-free as eye tracking (provided the research design is sound). That’s what makes eye tracking so valuable for basic research, though less for usability evaluation – as it only provides indirect information on usability. Most information on usability can be assessed with other, less extensive techniques. For example for web design most of the time you’ll just find out whether a given element has been seen or not. (…) The question is whether this information could not have been gotten by easier, e.g. through an interview. In lots of cases the client insist on eye tracking because it’s ‘sexy’ and because you can impress other clients or the organization executing the project. So, I’d say: eye tracking is an indispensable technique, but it’s not, however, indispensable in the area of usability evaluation (personal communication, May 9, 2006).
The funny thing is that lots of researchers and practitioners know this fact. But few people say so. There is big money in eye tracking, and the heat maps are great for senior management presentations. I think that’s the biggest reason eye tracking is the latest hype in the usability field.
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Strange enough so many UI-Professionals still don’t seem to adress what is relevant in Usability Evaluation:
Finding out where to improve the fit between process- and taskrequirements (wich include requirements of the user himself) and the given implementational state of a certain system.
You can’t directly tell from the eye-movements, where a taskanalysis failed or where the realization of the analysis shows weak points. All you can achieve is information on how the user interacts with the plain layout.
So afterall: Eyetracking is lengthy and costly and you cannot achieve the major intended information. Nothing against a quantitative behaviourist-based way of dealing scientifically with Usability of GUIs, but what is the hype for?
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