Introduction

SR Research EyeLink eye trackers allow for accurate gaze and pupil measurements. 

Availability, support and advice

At FSW Leiden a few EyeLink 1000 (or EyeLink 1000 plus) eye trackers are used and one is available at the LIBC MRI scanner. SOLO supports EyeLink devices, but does not provide support EyeLink software, such as Experiment Builder or Data Viewer. 

To use EyeLink with stimulus presentation software, see the OpenSesame and EyeLink and E-Prime and EyeLink pages.

EyeLink Setup

The EyeLink 1000/1000 plus system consists of an eye tracking camera, a host PC, accessories (mouse, keyboard) and a screen. The EyeLink host PC is connected with the stimulus PC on which the stimulus presentation software runs (e.g. OpenSesame, E-Prime, etc.) through ethernet cable. 

Configure network connection on stimulus PC

The network of the stimulus PC needs to be configured so that communication with the EyeLink host PC is possible. For a Windows PC, the following instructions should be followed (full instructions can be found here, note that an SR-research account is necessary to view the thread).

• Connect the Host PC to the Display PC via an ethernet cable.
• Go to the Control Panel ⇒ Network and Internet ⇒ Network and Sharing Center ⇒ double click on the correct Ethernet.
• Click the Properties button to open the Ethernet Properties.
• Select the Internet Protocol Version 4 (TCP / IPv4) item.
• Click the Properties button to open the TCP / IPv4 Properties.
• Select the "Use the following IP address:" and enter 100.1.1.2 for IP address and 255.255.255.0 for subnet mask (leave the Default gateway blank).

Tips & Tricks

• Recording pupil size
  When recording pupil size, it is recommended to use the Head-Fixed mode. This means that a chinrest is necessary to secure the participant's head.
   
• Convert pupil size to mm
  EyeLink reports pupil size as an arbitrary unit, which is based on the number of pixels the pupil consists of, as measured with the eye tracker's camera. After data collection, the pupil size can be converted to mm. This can be done by using an artificial eye, or by printing out a black circle with a known diameter. Note that the conversion steps can be done once, only if the data was collected with Head-Fixed mode (using a chin rest), and the camera was kept at the same distance for all participants. Below, links to instructions on how to convert pupil size to mm are given:
  • Instructions are provided here (note: you need to register to be able to view forum threads)
  • See How to: Convert EyeLink Pupil Size Data into Millimeters for a video with instructions

Resources

• SR Research EyeLink website
• SR Research support forum. Here you can find manuals, webinars, FAQ, and much more. You need to register to be able to view the threads.