Ramdomization Issues

Hi. I am creating an IAT and have gotten a bit stumped on randomization.

For example, on a block with flower and good on the right and insect and bad on the left, I have 5 words per stimulus category in my text files. I would like to run 30 trials in the block in random order except that I would like the trials to alternate between either flower/insect and good/bad. So the trials would be random, but alternate between presenting a target and then adjective stimulus.

However, I haven't been able to figure out how to randomize this way. In looking at the sample IAT input file, I see that they are randomized in this way, except that they are running 8 trials with an equal number of trials per category. With my setup of 30 trials, this doesn't work because some of the target and adjective stim lists automatically get more trials because of the way they must be listed. Is there a way to do what I'm trying to do?

So does 5 divide equally into the number of times you call each stimulus within the block?

I don't think so. I have 4 files of stimulus lists that I'm calling from for one block (target1, target2, adject1, adject2). There are 5 stimulus words in each of those lists. I would like to do 30 random trials but that alternate between listing one of the target words and one of the adjective words.

For example, the way the stimuli are listed in the example IAT are:
target1
adject1
target1
adject1
target2
adject2
target2
adject2

So basically, what I want to set up is exactly like the sample IAT, except that each stimulus file has 5 words instead of 4 and I want to have 30 random trials instead of 8. So the set-up of the sample IAT produces the effect I want, but because they are only calling for 8 trials, the 4 categories of stimulus equally divide between the trials so that each stimulus list is called on 2 times.

With my setup of 30 trials this does not work to list them this way because if I just list 30 trials some lists would have to necessarily be used more than others. I thought that one potential fix could be to list 40 trials, but put a skip after the 30th trial to go to the next block (that way they’re evenly divided, but still random). However, I read in the manual that to do this, the trial on which you want to place the skip (so for me, trial 30) would have to be fixed. Is there any way to have all 30 trials random instead of having to fix one of them in place? Or is there another method besides skipping that would set up my block this way?

Might be easier if I could see your input file and stimlists. Could you reduce a sample version to just 1 block so that I can see exactly what you've got? Basically, whatever the bare minimum number of trials is that's required to illustrate the problem.

I emailed you a zip folder with the input and stim files.