(no subject)

[Jan Seifert]

> Dear all,
> we would like to vary our interstimulus interval (ISI) randomly during the 
> experiment. We can't see any simple solution to this problem without the 
> stimuli being coupled in a fixed manner to a certain ISI. Have you got 
> any suggestions?
> Thank you very much for your support
> Dirk

Hello Dirk,

there are two ways you can adjust ISI's. You can make one list for every 
subject. Such List-files have to be a tab-delimited text-files with header 
in the first line. With an inline-script you can load the required list:

'''''''''''''''''''''''''''''''''''''''''''''
' InLine - LoadList BEGIN
'''''''''''''''''''''''''''''''''''''''''''''
List.LoadMethod = ebLoadMethodFile
List.Filename = ".\\Listen\\random" + c.GetAttrib("Subject") + ".txt"      
'filenames look like "random13.txt" for subject 13.
List.Load
'''''''''''''''''''''''''''''''''''''''''''''
' InLine - LoadList END
'''''''''''''''''''''''''''''''''''''''''''''


Another way could be that you do not load the whole list in advance, but 
you change only the order of the ISI's.
The code is approximately like this:

'''''''''''''''''''''''''''''''''''''''''''''
' InLine - ShuffleISI BEGIN
'''''''''''''''''''''''''''''''''''''''''''''
For i = 1 To List.Size
	'Exchange ISI[i] and and randomly chosen ISI
	dummy = List.GetAttrib(i, "ISI")
	LevelToExchange  = Random(i,List.Size)
	List.SetAttrib 1, "ISI", List.GetAttrib(LevelToExchange, "ISI")
	List.SetAttrib(LevelToExchange, dummy)
Next i
List.Reset 'Important! Reset the List
'''''''''''''''''''''''''''''''''''''''''''''
' InLine - LoadList END
'''''''''''''''''''''''''''''''''''''''''''''


Hope this helps,  Jan Seifert

/
\ Jan Seifert
\ Fachbereich I - Psychologie
\ Universität Trier
\ 54286 Trier
\
\ Tel. (+49) 651 201-2896
\ seif1301 at uni-trier.de
\ http://eeglab.uni-trier.de/staff/seifert.php
/