SpinozaWiki:Eyelink+Presentation+MRI Help Guide
From SpinozaWiki
Eyelink + Presentation + MRI Help Guide
6 Feb2011
Olympia Colizoli
Tomas Knapen
Renee Visser
University of Amsterdam
Help Guide for Preslink
Windows PC-> Start -> Programs -> SR research -> EyeLink -> Programming -> Runtime AP -> PresLink -> PresLink User’s Guide
Configuration
Installation and initial configuration is already done at the Spinoza center.
Configuration guidelines in PresLink manual.
Also, see internet configuration (back of manual)
Setup Eyelink
1 Turn on Presentation computer with the option “Meting met EyeLink”
2 Turn on and check the level of the battery in the scanning room.
- If less than 2-3 hours, the eye-tracker will not function properly. The illuminator will be flickery. This results in large short-lasting spikes in the traces. Replace the battery with the new battery and plug in the old one to charge. It is best if the battery is fully charged. If it is less it will probably not last a full hour.
- After use put the battery on the charger for about 1-2 hours. Make sure to leave it fully charged for the next user. Do not leave it on the charger longer than necessary (do not leave it overnight!), because this will hurt the performance of the battery.
3 Take off the lens cap
4 Turn on EyeLink computer & monitor
5 Choose EyeLink mode (not Windows mode)
If Eyelink doesn’t start: elcl.exe in DOS on Eyelink computer
To get old EDF files, start in Windows mode Look in the elcl folder the data
Test EyeLink Connection
Initially, the connection will be closed between the PC and EyeLink computers, even if the IP address is configured properly.
EyeLink says ‘Link Closed’
To Open the Link.....
Test configuration without Presentation
It is not always convenient to check the connection or to do a calibration through Presentation.
Start -> Programs -> SR Research -> EyeLink-> TRACK
This will open a screen connected to EyeLink without Presentation.
You can do a calibration or adjust the camera/focus this way.
Commands
Most of the keyboard commands work from both the EyeLink and Presentation computers.You can also use the mouse on the EyeLink computer.
ENTER - show eye on monitor
Left/Right - zoom in on eye
C - calibration
SPACE - start calibration
ENTER - accept calibration
V - validation
SPACE - start validation
ENTER - accept validation
Within Presentation:
F4 ->either back to eye screen, or start of experiment
ENTER -> accept drift check (when you see fixation point in center of screen)
F4 -> start experiment
D - Drift check (correct for eye movement on one central fixation point)
Enter - accept drift correction
Camera Setup/Calibration
Check your sample rate
At the MRI scanner, lowering the sample rate to less than 2K can help with the stability of the eyetracker.
9-pt calibration is standard, but more difficult subjects can be given a 6-pt or 3-pt calibration
Turn off ‘Manual Accept Fixation’ if you want the fixation point to move automatically once the position is registered.
Calibration improves when:
1. Tell the subjects to look at the middle of the cross in the fixation square
2. Tell the subjects not move your eyes until the fixation square moves.
Validation should show that all points are under 1.00
NOTE:
EDF file names cannot exceed 8 characters,
Which means that your SUBJECT NAME cannot exceed 8 characters!
If it does, you will get an error when the EDF file is transferred to the Presentation computer
Clean-up
Remember to take care of the equipment:
1. “Exit EyeLink” -> DOS Mode -> Power button OFF
2. Lens cap -> back on
3. Turn off battery and recharge for about 1-2 hours. Make sure to leave it fully charged for the next user. Do not leave it on the charger longer than necessary (do not leave it overnight!), because this will hurt the performance of the battery. If performance goes down, ask Joris from the NIN to replace the accu, [email protected].
4. Turn off EyeLink monitor
Converting EDF files to ASC
The EDF files are not in a readable format. In order to use them, you must convert them to ASC. This must be done from the command line on a computer with EyeLink installed.
The code for this conversion is in the Examples folder of the EDF Access API folder.
c:\Program Files\SR Research\EyeLink\edf_Access_API\example
Start-> RUN -> CMD -> set CD to EDF Acces API folder (copy paste directory), which contains edf2asc.exe.
To get a list of all arguments for this function, just type edf2asc
edf2asc –s locationofedffile\filename.edf (-s gives all samples)
edf2asc –e locationofedffile\filename.edf (-e gives all events)
In between these two command lines make sure to rename the .asc file (eg. filename_s.asc for sample file and nameoffile_e.asc for event file) before converting the next one, otherwise the .asc file will be overwritten.
Programming in Presentation with EyeLink Scenario Files with EyeLink code
Check out the example file “track.sce” for an example of using Presentation scripts with EyeLink.
A copy of this code is in the PresLink user guide.
Most of the code can remain, but you must make sure to specify when you want to send a message to the eyetracker EDF file. For example, at the start and end of a trial.
tracker.send_message(“some string”);
Note: EDF file names cannot exceed 8 characters.