The VEP experiment uses a HTML files
with java scripting to display the flashes and the checkerboard to
evoke VEPs. To modify the number of stimuli you need to make a little
modification on the code. Please do only so if you feel comfortable
to do such changes.
Use the 'Install Experiment' LabAuthor Utility to install the VEP experiment to your local PC. Navigate to the Experiment Files folder on your
computer. By default they are located under
C:\Users\Public\Public Documents\ADInstruments\LabTutor\Experiment Files
Within the folder 'Visual Evoked
Potential (VEP)' open the 'Support Files' folder and open flash.html
and checker.html with a text editor, e.g. with Notepad++.
In flash.html locate in line 17 the
code:
if(c==101) { clearTimeout(t);
window.close();}
Change the value for c to your needs,
say to 121, save and close.
In checker.html locate in line 32 the
code
if(c==101) { clearTimeout(t);
window.close();
Change the value for c to your needs,
say to 121, save and close.
Now that you have changed the number of
stimuli presentation you need to change the number of scope averaging
within the LabTutor experiment.
Open the LabTutor experiment with
LabAuthor and change to the LabTutor Kernel window.
Within the scope View window click
'Event Settings..' and change the Average value to 120 and click
'OK'. Then go to Setup > Sampling... and change the Scope Average
to 120 and 'Close'.
Go back to the LabAuthor window and
change the text fields in the Contend Pages accordingly (… 100
sweeps... should be replaced by … 120 sweeps...).
Edit the Experiment Properties, save
the file and export a new experiment installer, which then can be
uploaded to your LabTutor Server.