Hello,

I have a problem with a randomize prime presentation. I have 8 primes, 9 positive and 9 negative targets. I've already looked at http://www.millisecond.com/forums/Topic2270.aspx but although I thougt, that I understand the procedere, it doesn't work.

So here is my script:

<counter prime>
/ select = noreplace
/ items = (
1,1,1,1,1,1,1,1,1,

2,2,2,2,2,2,2,2,2,

3,3,3,3,3,3,3,3,3,

4,4,4,4,4,4,4,4,4,

5,5,5,5,5,5,5,5,5,

6,6,6,6,6,6,6,6,6,

7,7,7,7,7,7,7,7,7,

8,8,8,8,8,8,8,8,8)
</counter>

<counter target_positive>
/ select = current(prime)
/ items = (
1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9)
</counter>

<counter target_negative>
/ select = current(prime)
/ items = (
1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9,

1,2,3,4,5,6,7,8,9)
</counter>

<trial prime>
/stimulusframes = [1-19=prime; 20-27=blank ;28=noreplace(target_positiv, target_negativ)]
/validresponse = ("a", "l")
/response = timeout (2200)
/posttrialpause = (2500)
</trial>

<trial break>
/stimulusframes = [1=blank]
/response = timeout (60000)
</trial>

<block prime>
/screencolor = (255,255,255)
/preinstructions = (Berufe)
/trials = [1= clock; 2-37=noreplace(prime); 38=break; 39=clock; 40-75=noreplace(prime); 76=break;
77=clock; 78-113=noreplace(prime); 114=break; 115=clock; 116-151=noreplace(prime)]
</block>

The Block is running, but I always find some repetitions.

Can it be because I use the targets in another block before?

Thanks for help, Rita

The problem is that both 'target' counters depend on the same, single 'prime' counter. Assuming you want to combine every prime with (a) every positive target as well as (b) every negative target, you need two 'prime' counters.