Eyetracking has a mystery to it for some reason. Perhaps it’s the perception that scientists can catch glimpses of your thoughts but more than anything it’s the unknown of how the technology works. As cool as seeing into one’s mind is, eyetracking can not record your personal thoughts like in Minority Report (I’m sure someone is  working on it though).

Eyetracking can be defined as a technique that is used to record and measure eye movements. Definition is simple enough, but I always get a follow-up of “how does it record” and “will it hurt”? First let me say no it will not hurt, second you will not go blind, and third you will not become a mutant-sorry. At User First we use the Tobii T60 model, so I will discuss how this equipment works specifically.

Fantastic Machinery, The Eye

Imagine if you will that you are looking out a window from your home or office onto a city street.  As you look outside, your eyes are constantly moving.  Some of these movements are conscious.  For example, you notice the movement of a dog and glance above it for a glimpse of its owner.  But more so your eyes are moving involuntarily, focusing only on certain areas of the visual field in order to form a picture of the scene for your brain. The human eye is a fantastic piece of machinery; it is not capable of absorbing 100% of the visual field in an instant with clarity. We call the area of the eye capable of this focus the foveal area and the brief pauses of our gaze the fixations. The foveal area accounts for only 8% of the visual field at any one time but supplies 50% of the visual data received by our brain.  And the movement of the eye controls which regions of the visual field we fixate on and which regions are ignored and left to the poor acuity of our peripheral vision which is only useful for picking up movement and strong contrast.

So how are Eye Movements Tracked?

Just as the human eye relies on the focus and detection of light to see, so does the most common technique used to track eye movements called Pupil Centre Corneal Reflection (PCCR).  This technique is non-intrusive and the technology making it possible comes in two forms: either a specially equipped computer monitor or a head-mounted device.  Both options use a light source to illuminate the eye causing highly visible reflections.  The illumination is near infrared and therefore unnoticeable to the user but creates reflection patterns on the cornea and pupil of the eye and two image sensors on either the computer monitor or the head-mounted device are used to capture images of the eyes and the reflection patterns.  A computer then uses advanced image processing algorithms and a physiological 3D model of the eye to estimate the position of the eye in space and the point of gaze with high accuracy.

The location of these gaze points during each fixation, the time spent on each fixation, and the pattern in movement from one gaze point to another are the key pieces of data collected during an eye tracking study.  These data can then be visualized using a gaze plot or a heatmap.

CAPTION: The Gaze Plot visualization shows the movement sequence and position of fixations (dots) and saccades (lines) on the observed image or visual scene.

CAPTION: The Heatmap visualization highlights the areas of the image where the participants fixated. Warm colors indicate areas where the participants either fixated for a long time or at many occasions.

Not only can we determine what and how visual information is consumed but patterns in eye movement tell us more.  Emotional responses are evident in eye movement patterns and thus allow us to connect physical behavior of the eye to cognitive behavior in the brain.  This is why eyetracking is a strong supplement to traditional qualitative studies.  They allow a scientific measure beyond the subjective responses provided by a participant in an interview.

Eyetracking is especially important in the age of mass media.  The amount of content, the speed at which it is delivered, and the speed at which a user consumes it, means users make less and less time fixated on each image.

How will your message not get lost?  How will your brand be recognized? Question please don’t hesitate to ask.