Its not just what people look at that’s important, but what they don’t look at is key too.
To understand this concept, we need understand a bit about how the eye works. A Tobii eye tracking white paper, released in January 2010 shows just how complex the eye really is. What really struck me reading the paper was how much our peripheral vision affects our experience of the World.
Human vision has evolved so we can see in both dark and light conditions. And we can see detail, but also can change what we look at very quickly. We use different parts of the eye for these purposes. We see detail with the small foveal region of the eye, which is better suited to good light conditions.
The larger part of the eye, the peripheral region, is better suited to poor light conditions. It can detect movement, and contrasts between colours and shapes, but the compromise is that our vision here is blurry.
When we look at something, the foveal region of the eye pauses on the area of focus. An eye tracker measures these pauses, or fixations, and the movement between the fixations, the saacades. During a saacade, we don’t actually ‘see’ anything. No messages are sent to the brain.
On the image above fixations are represented by the dots, and the path of the saacades by the lines. The bigger the dot, the longer someone has looked at that spot.
When we eye track a website, we can easily see the area of the screen where users didn’t look. No lines or dots mean there was no fixation it. However, we need to be careful when interpreting this data. Many people would say it is not viewed at all. But this may not be true!
No data on an area doesn’t mean that the area did not register with the user. With our peripheral vision, we can detect movements and register contrasts between colours and shapes. The user may have seen the area with their peripheral vision, thought it was an ad, and decided not to go there! This has previously been termed ‘unlooking’ by eye tracking researchers.
In this context, it is important to ask someone why they haven’t looked at a part of the screen. And we can only know this if we track them! We use a retrospective think aloud (RTA) method for this reason. The participant’s eye tracking video is replayed to them immediately after they have finished a task and questions asked about their experience and perception of the parts of the page they didn’t look at.
I did have one user who said they thought a coloured block was an ad, so they didn’t look at it, even though it was a government site! Now I am keen to study reasons for ‘unlooking’ at my next eye tracking session.