By sanahadd - 4/11/2016
Hello,
I'm currently trying to run a simple word vs. non-word lexical decision task. There are 21 category (i.e., target) words, 21 neutral words, and 42 non-words. This is my script for the block:
<block lexicalDecisionTask>
/ trials = [1=instructions; 2-85=noreplace(ldtcategory, ldtneutral, ldtnonword)]
</block>
However, I noticed that some words are appearing more than once. I just want ALL of the words (category, neutral, and non-word) to appear ONLY ONCE. How do I need to re-word the script? Thanks!
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By Dave - 4/11/2016
The answer entirely depends on how many items there are for each type of trial.
/ trials = [1=instructions; 2-85=noreplace(ldtcategory, ldtneutral, ldtnonword)]
You are running a total of 84 trials here, and you have instructed the script to run ldtcategory, ldtneutral, and ldtnonword in *equal* proportions: There will be 28 ldtcategory trials, 28 ldtneutral trials, and 28 ldtnonword trials.
If, for example, you have twice as many ldtnonword items (42) as ldtcategory and ldtneutral items (21 each), that needs to be reflected in the proportions you enter:
/ trials = [1=instructions; 2-85=noreplace(ldtcategory, ldtneutral, ldtnonword, ldtnonword)]
will result in 21 ldtcategory trials, 21 ldtneutral trials, and twice as many -- 42 -- ldtnonword trials, a 1:1:2 ratio.
You will find this covered in the documentation for the <block> element's /trials attribute.
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