Eye link 1000 plus:
The new eye tracker system installed in the MEG lab is an Eye Link 1000 plus. It give you an extremely precision measure of the eye position and pupil diameter and it has been design for MEG.
All the part are non-ferromagnetic and compatible with the MEG and data are transfer by a fiber optic directly on the eye tracker PC and with analog output stream the online on the .fif file.
This brief guide give to the user some basic knowledge about ETL1000 hardware connection with the Camera and the MEG's stimulation machine (Alienware PC) see image below.
The second part will answer to FAQ about default camera and screen setting, and in the last part some code it is provide to control all this setting directly from the stimulation machine.
Starting Host Application and Demos
Before turning on the host PC, open the stimulation cabinet and make sure that the power supply of the ET camera (filter DC power) is connected.
Always leave the ET on its support, and the optical fibers always connected (be careful because they are very delicate), therefore remember to turn off the power supply at the end of recording to avoid that the LEDs of the illuminator remain on.
Turn on the Host PC (ET PC) and select the 'EyeLink' partition.
From the stimulation PC run this demo EyelinkExampleVPixxDemo.m to:
- Check the connection between the ET PC and stimulation PC,
- Call the eyelink_INIT_VPixx.m function, which set automatically all the commands of the Camera Setup Screen and Set Option Screen (see attachment),
- Create, save and transfer .edf data from ET PC to stimulation PC (remember that the name of the edf file must not exceed eight characters),
- Send the stimulus fixation cross to the host PC to check the participant's movements during the experiment.
If you want to try the demo without a participant, select the 'Simulating Using Mouse' command from the Set option Screen Main function or use the command line:
Eyelink ('command', 'aux_mouse_simulation = ON');
Once the participant is in the MEG helmet press ENTER from the calibration window, move with the arrows on the keyboard to have the eyes projected on the whiteboard inside the shielded room to focus manually.
FAQ
What are the default Camera settings of the eye tracker Long Range?
The default camera setting make you change some parameters about image threshold, tracking mode, sample rate and image display. All the buttons are on the left side on the Main screen (see image above).
Before start, make sure that you have all the following default camera settings:
Tracking mode: Pupil-CR (Corneal Reflection),
Sampling rate: 1000 Hz,
Pupil tracking method: Centroid Model,
Image Display: Crosshair, Threshold Coloring, Image->Display PC,
Power level of the illuminators: 75%,
Eye tracker: Both (Binocular).
What are the default screen settings of the eye tracker Long Range?
Many different options can be set up for the screen the followed setting in specific for the Long Range mount. All the buttons are on the right of the main screen button:
Before start, make sure that you have the follow configuration:
Calibration Type: nine-point,
Pacing Interval (between calibration and validation): 1000 ms,
Target presentation order: Random
Redisplay the first calibration or validation target,
Search Limits, useful for images with reflections off of glasses or makeup,
Pupil size data: AREA recorded in scaled image pixels,
Eye events data (record fixations and saccades): GAZE coordinate,
Sensitivity for saccade event generation: NORMAL,
File Sample filter (level of data recorded to the EDF file): EXTRA,
Link/analog Filter: filter level for data available via Ethernet link: STD,
Analog Output (type of data for analog output): GAZE.
Where does the eye-tracker stream the online estimates about X, Y position and pupil diameter?
The online estimates about X, Y position and pupil diameter are stream online on .fif file. Six analog output are available on the MISC channels, with the following specifications:
MISC1=RX (Right eye, X axis)
MISC2=RY (Right eye, Y axis)
MISC3=RP (Right eye, Pupil size)
MISC4=LX (Left eye, X axis)
MISC5=LY (Left eye, Y axis)
MISC6=LP (Left eye, Pupil size)
Please make sure that the ‘Analog Output’ is set to Data RAW and MISC 1-6 are active in the acquisition PC.
Where are my recorded eye-data stored?
All recorded eye-position data are save in an edf-file stored in Eye tracker pc folder (ELCV/data).
The data can be download in a USB key directly from the PC or transfer from the eye-tracking computer to your folder on the stimulation computer at the end of the experiment or at the end of each block.
Please remember to download and save the .edf the data at the end of the day, because the ELCV/data folder will be empty once it is full.
What software can I use to analyses my recorded eye-data?
The EDF file format is a platform-portable binary record of the eye-position and synchronization events.
This format can be use to analyze the data for EyeLink Data Viewer application,
or alternatively filtrated by EDF2ASC utility into a text-format ASC file, to be integrate and implement with other software (e.g. E-Prime, Psychtoolbox, for MATLAB, Presentation, Python etc).
i.e. http://www.fieldtriptoolbox.org/getting_started/eyelink
Where can I analyse my eye-tracking data? Which computer has the license dongle for the software?
The eye-tracking data can be analyze on a PC in the eye-tracker room in Mattarello, where the last version of EyeLink Data Viewer is installed. The program runs only with stand-alone USB license key.
Please never remove the dongle from the PC.
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