History of Eye Tracking

Early observations of eye movements and gaze behaviour date back to the late 19th century, representing the foundation of eye tracking history. While the technology and methods were rudimentary by modern standards, these early observations laid the groundwork for the development of more advanced eye tracking techniques. In 1879, the French ophthalmologist Louis Émile Javal noticed, for the first time, that readers’ eyes do not skim fluently through the text while reading, but make quick movements mixed with short pauses. These studies were based on naked-eye observations in the absence of a more advanced technology. During the same period, the French physiologist Etienne-Jules Marey (1804 – 1904), known for his work on the physiology of the movement, developed photographic techniques to capture images of every kind of movements. His process, based on the chronophotograph, allowed for visual documentation of eye movements. These early attempts at recording eye movements contributed to our understanding of ocular motion.

In 1908, Edmund Huey (1870 – 1913), built a device which could track eye movement during the reading process. This first eye tracker was very intrusive as readers had to wear a type of contact lens with a small opening for the pupil. The lens was attached to a pointer which changed its position following the movements of the eye. Huey published his findings in the book The Psychology and Pedagogy of Reading.

Later trough the century, the development of eye-tracking equipment in the early to mid-20th century marked a significant advancement in the field of eye tracking. During this period, researchers and scientists began creating specialized devices to track and record eye movements more accurately.

The first dedicated eye-tracking laboratory was established in 1929 by Edmund T. Rolls at the University of Cambridge. This marked the formal recognition of eye tracking as a field of study.

In the early 1950s, the development of electrooculography revolutionized the field of eye tracking. EOG involves measuring the electrical potential generated by the movement of the eye's cornea and retina. By placing electrodes near the eyes, researchers could record voltage changes associated with eye movements. EOG provided a more accurate method for tracking eye movements than earlier techniques.

Alfred Lukyanovich Yarbus was a Soviet psychologist who studied eye movements in the 1950s and 1960s. Yarbus pioneered the study of saccadic exploration of complex images, by recording the eye movements performed by observers while viewing natural objects and scenes. In his 1965 book ("Eye Movements and Vision"), Yarbus showed that the trajectories followed by the gaze depend on the task that the observer must perform. 

The 1970s saw the development of the Pupil-Center Corneal Reflection technique, which became a standard method for tracking eye movements. PCCR involves shining a light on the eye and using the reflections from the cornea and the pupil to determine the point of gaze.

David A. Robinson was the first researcher to simultaneously record eye movements and activity of ocular motor neurons from fully alert behaving primates. The results produced the mathematical relationship known as the pulse-step of innervation. He predicted the necessity of a central neural network that holds positions of gaze—the ocular motor neural integrator—and discovered the anatomical location of the integrator. He also developed a concept for how the brain generates saccadic eye movements that has served as the foundation for subsequent saccades discoveries. Dr. Robinson is most famous for developing and using mathematical models to understand how the brain controls eye movement in health and things go wrong in disease. He set a new wave of quantitative studies focused on the neural circuits that control and calibrate movement. His research set the groundworks for neural engineering and computational modeling in furthering our understanding of the brain.  During the same period, Daniel E. Guitton, PhD focused on a critical problem in systems neuroscience which is to understand the link between the visual and gaze movement systems. Over the past 40 years and even today, his research focuses on how the neural circuits that generate eye and head movements bring the fovea onto salient features of the visual world. Guitton analyzes neural activity obtained by recording simultaneously from neurons in different visual and oculomotor areas of the brain. Another important component of his research is the study of visuo-motor deficits in neurological patients. He collaborates with Dr. C. Pack, a specialist in the visual system, and Dr. H.L. Galiana, an engineer specializing in the development of theoretical network and systems models of the brain’s visuo-motor control systems. Their objective is to develop models that can explain normal and pathological visuo-motor behaviour.

Recently, there has been a growing interest in developing more accessible, easy-to-use, scalable eye tracking solutions to bring them to the mainstream. Powered by advanced computational capabilities found in tablets today, Innodem Neurosciences, led by cognitive neurologist Dr. Étienne de Villers-Sidani, is developing a non-invasive, mobile eye tracking software solution – currently under investigation in multiple clinical trials – that can be downloaded to an iPad Pro making it easy to extract eye movement features in a clinical setting. The extracted eye movement biomarkers can be parsed locally by powerful machine learning algorithms to provide meaningful scores that are equivalent to Gold standard scales, so that the health care provider can monitor the patient’s disease status and progression remotely and adjust treatment accordingly.