Читать книгу Eye Tracking the User Experience - Aga Bojko - Страница 15

Your visual behavior is influenced by anything that makes you look (bottom-up attention), as well as your voluntary intent to look at something (top-down attention). Bottom-up attention is stimulusdriven. Attention is involuntarily shifted to objects that contrast with their surroundings in some way. For example, bright colors and movement can make you look at something. Things that are new and unexpected in a familiar 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.