What is eye tracking?

Eye tracking is a general term for techniques for measuring the point of gaze – where you are looking – or for determining eye/head position. Today a number of methods exist for measuring eye movements, and the number of application areas is even larger.

Analysis and eye control

Eye tracking can be used both for analysis applications and for interacting with computers and machines.

The ability to measure eye gaze adds value to behavioral research and analysis, since human behavior and thinking is reflected in where people look. Eye tracking is also a precise and robust method for defining the exact position of a person or the presence of eyes.

The major areas of analytic applications are academic research e.g. cognitive science, psychology and medical research; market research and usability studies, such as advertising or package design and software or web usability.

The eye tracking technique can also be used for interaction - people can control a computer and make things happen by just looking. It is then referred to as eye control. Eye control can be used as sole interaction technique or combined with keyboard, mouse, physical buttons and voice.

Eye control is for example used in communication devices for disabled persons and in various industrial and medical applications.

Non-intrusiveness is a key

Eye tracking studies have their origins in the 1800s, when studies of eye movements were made using direct observations. The first true eye tracker was composed of a contact lens with a hole for the pupil. The lens was connected to an aluminium pointer that moved in response to the movement of the eye. This was in the late 1800s.

Since then eye tracking has come a long way. The first less cumbersome eye trackers were built in the 1930s using beams of light that were reflected on the eye and recorded on film.

Today there are modern eye trackers that do not affect test subjects or users and that do not require extensive technical expertise. Non-intrusiveness and ease of use have been keys for taking eye tracking out of the research labs into broader use.

Accuracy for everyone

The embryo of today’s most commonly used eye tracking technique was developed in the late 1960s. It is called the pupil-center/corneal-reflection method, utilizing image processing to detect reflections in a person’s eyes.

The accuracy depends on how precisely the image processing algorithms can locate the relative positions of the pupil centre and the corneal reflection. There are two methods of enhancing the image of the pupil; bright eye and dark eye effect. Optimally these two methods can be combined to allow all users, regardless of age, origin and eye color, to be able to use an eye tracker.