Try Not To Blink—This Won’t Hurt
What exactly, is eye tracking? Do I have to put on a helmet or stick something unpleasant into my eye? No, nothing so invasive, and not the least bit uncomfortable. Eye tracking is the process by which eye movements are recorded for the purpose of tracking where a subject is looking, what he/she is looking at, and the duration of the subject’s gaze on a given area. Eye tracking differs from electrooculogram (EOG) in that it records where and at what the subject is actually looking, whereas EOG primarily records the movements of the eye muscles. Rather than merely recording eye movement and position, eye tracking forges an invisible yet accurate connection between the subject and the objects within the subject’s field of vision. These “visual connections” of where the subject was looking during the study are clearly visible in the resulting data, as dramatic as tire tracks on an impressionable surface.
So how does eye tracking work? Using invisible near-infrared light combined with high-definition cameras, the eye tracking system projects invisible light onto the eye and records the direction from which it is reflected off the cornea. Eye tracking software is used to calculate the exact position and focal point of the eye. The sophisticated combination of eye tracking hardware and software allows for extremely accurate measuring and analyzing of visual behavior and fine eye movements. This makes it possible to create a detailed map of a subject’s field of vision and the specific visual elements honed in on by the subject. Eye tracking data is commonly acquired in tandem with other body signals for the purpose of determining the effects of what we are looking at has on our physiology. Common signals acquired during eye tracking studies are:
- EEG (cognitive processes)
- EDA (alertness)
- ECG (anxiety)
- EMG (muscle activity, conditioning)
- EGG (pulse, respiration, temperature)
What are researchers looking for when conducting eye tracking studies? Eye tracking data is useful in a variety of different research fields including interface usability, reading analysis, psychological and emotional response, marketing research, training, clinical vision diagnosis, and more.
Eye tracking hardware mainly comes in two flavors. Screen based eye tracking involves having a subject sit in front of a computer monitor while being presented with various types of visual stimuli. A “bar type” eye tracker records the subject’s responses and interfaces with eye tracking software to present the stimulus and store the resulting data for analysis. BIOPAC’s AcqKnowledge software version 5.0.6 and higher, along with the BIOPAC MP160, MP36R, or Wireless Smart Center system, supports fully-integrated eye tracking functionality*. Rather than having to learn a second software program, the familiar AcqKnowledge interface has been extended to incorporate the EYE-TRACK-BAR and EYE-TRACK-BAR-XL remote screen eye tracking systems.
Mobile or “wearable” eye tracking systems utilize a pair of glasses with two types of built-in cameras. One camera faces the subject and tracks eye movements, gaze path, and other parameters, and a second camera (called a scene camera) records what the subject is looking at during the study. Mobile eye tracking allows the subject to engage in independent activities outside the lab, such as driving an automobile. Additional sensors record and log data from other body signals in real time, which can be loaded into the software for subsequent analysis.
For more information about eye tracking, we invite you to sign up for our free “Eye Tracking Fundamentals” webinar to be broadcast live on November 21, 2019 at 8:00 AM PST. Did you miss it or can’t attend? No problem. Follow the same link to watch it on demand.
*Eye Tracking Integration License for AcqKnowledge required.
Please also visit the following links for information about BIOPAC Eye Tracking products.
BIOPAC offers a wide array of wired and wireless equipment that can be used in your research. To find more information on solutions for recording and analyzing signals such as ECG, heart rate, respiration and more using any platforms mentioned in this blog post, you can visit the individual application pages on the BIOPAC website.
Photo by Marina Vitale on Unsplash