Eye tracking as an outward sign of an inward state
Attention is important, so how do we measure it? If we accept William James’ definition of attention, then this is harder than you might first think. Attention is, after all, something that goes on inside people’s heads.
To answer this question, Google recently commissioned the Ehrenberg Bass Institute to evaluate a number of different ways of measuring attention, from simple self-reported questionnaires to facial coding, head tracking, eye tracking, and all the way to approaches using brain-scanning technologies such as EEG and MRI.
Their conclusions, presented at the ARF Audience x Science conference in 2018, was that eye tracking and to an extent, head tracking (we’ll come on to the distinction between these two in the next section) were the most reliable and accessible means of estimating attention to advertising available.
Eye tracking is a good way of measuring attention because eyes are (a) important and (b) easy to measure. Our eyes are the most important sense organ we have, with 40% of our brain dedicated to vision.
Secondly, the eyes are the easiest of the senses to measure consistently and quantitatively. Most other senses ‘happen’ exclusively in the mind. It is hard to assess what people are hearing, feeling with touch, or smelling without asking them to tell us what they think they are experiencing.
Sight, too, ‘happens’ in the brain, but the movements of the eyes can be captured by external observation in a way that is currently impossible for sound, taste, touch, or smell. You can track eyes in a way that you can’t track the inner ear.
This is not to say that eye tracking is a perfect measure of attention. Sound is very important – ads can work very well on radio, or when the sound of a TV ad is playing in the background. Sensory data are composite: attending to sounds and pictures at the same time can result in greater memory encoding than one or other on its own. Finally, the eyes are not always a window to the soul: it is possible to stare blankly at a screen or a page without taking anything in.
But despite these limitations, Google still concluded that visual engagement – as measured by eye tracking or head tracking – is a good-enough proxy for measuring attention to visual advertising; not perfect, but a good start.
