random in nested lists

[Michiel Spape]

Hi,
This is usually a problem of a list randomisation; i.e. if you take a word out of the list, randomise the list, take a word, randomise again, the chance is pretty big you end up with the same word. You could either work it out so that the list isn't reset before completion, but if you're lazy (like me), you might also try to get rid of the nested lists and just write it all down into 1 giant list:

"rectangle presented before the target": word 1
"rectangle presented before the target": word 2
...
"rectangle presented before the target": word 10
"rectangle presented above the target": word 1

You'll end up with 6 x 10 different trial types, which some people don't find awfully elegant looking, but this makes a better point of making your design truly orthogonal. 

If you do, for some reason, feel the need to use nested lists, you might try defining it at a different level and checking how many times it is shuffled.
Best,
Mich

Michiel Spapé
Research Fellow
Perception & Action group
University of Nottingham
School of Psychology


-----Original Message-----
From: e-prime at googlegroups.com [mailto:e-prime at googlegroups.com] On Behalf Of Petrime
Sent: 13 April 2010 10:55
To: E-Prime
Subject: random in nested lists

Hi folks,
I'm an absolute E-Prime newbie, and I have one problem with my nested
lists solution, so I have no other choice, but to ask for your help.

In my experiment there are 10 words, and every word should be
presented in 6 different conditions (e.g. rectangle presented before
the target above the target location, or circle presented after the
target on the left side of the screen, and so on)...so in one trial
there should be one of this 10 words, presented in one of this 6
conditions...

I solved this with nested lists (hope this is right solution)...
There are 6 nested lists, one for every condition. Each list holds 3
attributes  (Word-Target,Location on the screen and Correct responce)
In every list selection is set to random.



The problem is that, sometimes , it selects the same word from this 6
lists, few times in a row ... e.g. it presents word >circle< 3 times
in a row, every time in different condition...

Is there some way to fix this? I tried many different things, but
nothing works...

I hope that there is someone out there, who can help me with this.

Thanks in advance.








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