Eye Tracking Facilities
As we go about our daily lives, our eyes are continually moving around, sampling the information that is available in the visual environment. For instance, if we want to know how somebody is feeling, we will fixate in turn on the different features of their face. When reading a story, our eyes will move from word to word, lingering on words that are more difficult to read, and backtracking when we realise that something doesnt quite make sense. And when we hear somebody talking, our eyes tend to be drawn to objects in the visual scene that we expect the speaker to mention next. By monitoring people’s eye-movements, it is possible to gain important insights into the underlying cognitive processes involved in completing these tasks.
Facilities in Cognitive Science
The department of Cognitive Science operates the following eye tracking systems. Each of these systems has different strengths, enabling a wide-range of applications.
|Eye Tracker||Mount||Location||Integrated Equipment||Ocularity||Sampling Rate|
|EyeLink 1000||Remote (Desktop)||Australian Hearing Hub||Standalone||Monocular||500 to 1000Hz|
|EyeLink 1000||Remote (Desktop)||Australian Hearing Hub||Biopac skin conductance (GSR) system||Monocular||500 to 1000Hz|
|Eyelink 1000||Remote (Desktop)||Macquarie University Hospital||Standalone||Monocular||500 to 1000Hz|
|EyeLink 1000||Tower||ERP Facility, Australian Hearing Hub||Neuroscan Synamps 2 EEG system||Monocular||1000Hz|
|EyeLink 1000||Long Range||KIT-Macquaire Brain Imaging Lab (MEG), Australian Hearing Hub||Adult and Child MEG system||Monocular||1000Hz|
|EyeLink 1000||Long Range||Macquarie Medical Imaging (MRI), Macquarie University Hospital||fMRI Scanner||Monocular||1000Hz|
|Eyelink II||Head||Australian Hearing Hub||Standalone||Binocular||500Hz|
|ASL EYE-TRAC||Head||Cognition in Action Facility, Australian Hearing Hub||Northern Digital (NDI) Optotrak||Monocular||320Hz|
EyeLink 1000 remote eye trackers
The EyeLink remote eyetracking systems incorporate a small camera and infra-red illuminator mounted on the desktop in front of the display screen. Participants wear a small circular sticker on their forehead, which enables the system to track their head position as they move around freely (around 20cm in any direction). This makes the system particularly suitable for testing children and other special populations. The remote system operates at 500Hz, but can record at 1000Hz and with higher spatial resolution if the participant's head is stabilized using a chin-rest.
Each remote system is by default setup for use with a chin-rest or in the remote configuration. Change between one or the other requires changing the lens that is installed in the system and needs to be organised with the eye-tracking oversight committee in-advance of booking subjects.
EyeLink II head-mounted eye-tracker
The system uses three cameras: two high speed cameras allow for binocular (or dominant-eye monocular) recording of eye movements; the third camera tracks four infrared markers mounted on the display screen, allowing the EyeLink software to automatically compensate for small head movements by tracking the position of the subject's head in relation to these markers on the screen. This means that a chin rest, or head restraint, is not required. Pupil measurements are recorded at a rate of 500 Hz (one sample every 2 milliseconds). The head-mounted tracker is currently the only system in this department that enables binocular recording. It is particularly suitable for research that involves interaction with a touch-screen. In principle, it could be upgraded (at cost) to allow eye-tracking of interactions with 3-dimensional objects.
EyeLink 1000 tower-mounted system
The tower-mounted EyeLink 1000 system provides the greatest spatial and temporal resolution. To achieve this, the participant's head must be stabilized on a chin-rest. The camera is positioned above the chinrest and monitors their eye-movements via a mirror placed between the participant and the computer screen. The mirror reflects infra-red light but visible light passes through, so the participant’s view of the computer screen is not affected. Our tower-mounted eye-tracker is integrated with a Neuroscan EEG system, allowing brain responses to be time-locked to fixation on particular areas of interest on the screen.