We have a little problem with a log file, concerning the responses of a participant:
We showed 159 images twice, asking each time for a different response. In our stim list we have 160 stimuli, which explains why in one case one image was only shown in the first part, but not in the second. But there is another thing that we cannot explain: During the second part of the experiment one picture was presented twice. We checked that we used the correct sign ($) for the randomization without replacement and since there are more stimuli than trials there was no need for representing a stimulus twice. Have you got any idea what might have gone wrong? Thank you very much for your help.