Hi Jens,
I tried this out but I'm not getting any matches. The script I used is below. Perhaps if you compare it with yours you might get a hint about the problem. If not, could you send a more extended snippet that includes the trial definition?
<text right>
/ items = zahlen
/ position = (60%,50%)
/ fontstyle = ("Verdana", 24pt, false, false, false, false, 5, 0)
</text>
<text left_large>
/ items = zahlen
/ position = (40%,50%)
/ fontstyle = ("Verdana", 40pt, false, false, false, false, 5, 0)
/ select = replacenot(right)
</text>
<item zahlen>
/1 = "1"
/ 2 = "2"
/ 3 = "3"
/ 4 = "4"
/ 5 = "5"
/ 6 = "6"
/ 7 = "7"
/ 8 = "8"
/ 9 = "9"
</item>
<trial selectreplacenot>
/ stimulusframes = [1=right, left_large]
/ validresponse = (" ")
</trial>
<block selectreplacenot>
/ trials = [1-100=selectreplacenot]
</block>
<expt selectreplacenot>
/ blocks = [1=selectreplacenot]
</expt>