Staircase procedure in E-prime

[Bronwyn Glaser]

Hello, I designed a task that may be useful to you. The subject  
needed to differentiate between the length of two stimuli, the second  
of which automatically adjusted in terms of the first (a stimuli that  
was always 4000ms long) in order to find a time threshold for the  
participant. In my experiment, there are two blocks that randomly  
alternate, one that is for the stimuli less than 4000 and the other  
for the stimuli greater than 4050. Here is an example of the script  
in the procedure for the stimuli greater than 4050:

Below I have pasted some script that may be useful to you:
'If answer is right, decrease Stimulus time on next trial by 50ms
If Response. ACC=1 and x>4050 Then
	x=x-50
'If answer is right and x already =4050, keep x the same
ElseIf Response.ACC=1 and x=4050 Then
	x=4050
'If answer is wrong, increase Stimulus time on next trial by 50ms
Else
	x=x+50
End If

With this script, you will need to declare the x globally and reset  
the attribute for stimulus time equal to x for each trial.

I hope this helps,
Bronwyn Glaser


On 8 nov. 05, at 14:18, Rachel Mitchell wrote:

>  Hi everbody.
>
> A colleague of mine wishes to programme a staircase procedure for some
> vision/psychophysical studies, and is interested in the possibility  
> of using
> E-prime for this.
> Specifically, he wants to create an experiment using a staircase  
> procedure
> to determine a threshold by establishing the temporal threshold for a
> temporal-order judgement task (in which participants simply report  
> which of
> 2 visual stimuli appear first) using multiple staircases.
>
> I wondered if any of you might have experience with using E-prime  
> in this
> way.
> Does anyone have any comments or advice?
> Perhaps even an example of these kind of procedures already set up  
> using
> E-prime?
>
> Many thanks
> Rachel Mitchell
>
>
> ---------------------------------------------------------------------- 
> -
> Dr Rachel L. C. Mitchell
> Lecturer in Cognitive Psychology, University of Reading.
> Honorary Research Fellow, Institute of Psychiatry.
> Research Psychologist, Berkshire Healthcare NHS Trust.
>
> Correspondence Address:
> School of Psychology
> Whiteknights Road
> University of Reading
> Reading
> Berkshire
> RG6 6AL
>
> Tel: +44 (0)118 378 8523
> Direct Dial: +44 (0)118 378 7530
> Fax: +44 (0)118 378 6715
> ---------------------------------------------------------------------- 
> -
>
>
>
>
>