Fwd: How to determine/maintain probabilistic ratios of stimuli presentations

[David McFarlane]

Ravinda

Stock reminder:  1) I do not work for PST.  2) 
PST's trained staff takes any and all questions 
at 
http://support.pstnet.com/e%2Dprime/support/login.asp 
, and they strive to respond to all requests in 
24-48 hours -- this is pretty much their 
substitute for proper documentation, so make full 
use of it.  3) If you do get an answer from PST 
Web Support, please extend the courtesy of 
posting their reply back here for the sake of others.

That said, here is my take...

At 8/15/2011 10:37 AM Monday, you wrote:
>Hi there,
>
>I am new at e-prime. I wish to know the following:
>
>1] How to maintain/determine probabilistic ratios of two kinds of
>stimuli (say, a blue and a yellow square) for their appearance on comp
>screen over a hundred trials, such that on most key-presses their
>predetermined/desired ratios are maintained?

Not sure I fully understand your question, and if 
I did I would probably not have an answer.  But 
if you merely mean to randomly present, say, 20 
blue squares and 80 yellow squares over 100 
trials, then you might simply make a List with 
one row for blue squares, one row for yellow 
squares, and set Weights to 20 and 80, respectively.

>2] How to initialize and declare GLOBAL variables in e-prime?

This is covered in Chapter 4 of the User's Guide 
that came with E-Prime.  In general, everyone who 
uses E-Prime should first work through *all* the 
tutorials in the Getting Started and User's 
Guides before starting their first project.  You 
might also try Michiel Spapé's E-Primer at 
<http://step.psy.cmu.edu/materials/EPrimer.pdf>http://step.psy.cmu.edu/materials/EPrimer.pdf 
.

>3] There seems to be some problem with the Debug.print portion in the
>code I have written. I am not able to figure out what the problem is.
>
>I shall be grateful for help.
>
>Thanks,
>Ravindra

-- David McFarlane, Professional Faultfinder

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