Problems with block set-up and calling files from file pool

dandriola

I am new to Open Sesame and experiment building, so I apologize for the length of my question and possible lack of clarity. Will be happy to provide more detail as necessary.

I am trying to set up an object matching task in which there is a pair of pictures that either match or mismatch. Each trial shows the picture pair saved as one file (e.g. cue_dog_match.jpg; cue_dog_cat_mismatch.jpg). I set the variables to "pair" with values of "match" and "mismatch" and correct_response "A" and "L" respectively.

I have 2 main problems (that I know of):
I want each block to have 6 blocks with only 5 trials in each block (I am testing very young children), but because I have 2 rows of variables I can only get even number trials per block. Is there a way around this?

I also want each block to randomly call match and mismatch items. However, even when I replace the script on the sketchpad with "cue_[pair].jpg" I get errors. (I also tried this with numerous file name conventions, but nothing is working).

Any help is appreciated.

eduard

Hi

I want each block to have 6 blocks with only 5 trials in each block (I am testing very young children), but because I have 2 rows of variables I can only get even number trials per block. Is there a way around this?

Well, are blocks of 4 or 6 trials that much unacceptable? That would be the easiest fix. In any case, I'd recommend to have the number of unique conditions matched for every block (in your case, same number of match/mismatch), so that you would always end up with something even. But if you really want to go for 5 iterations, setting the repeat value to 2.5 should do the trick.

I also want each block to randomly call match and mismatch items. However, even when I replace the script on the sketchpad with "cue_[pair].jpg" I get errors. (I also tried this with numerous file name conventions, but nothing is working).

If you want to use the loop_table to directly link to your images so that cue_[pair].jpg would work, you need to specify the file names in the loop table. I'm not sure whether you want that. Alternatively, you can define the list with all your stimuli, separately for match and mismatch, in the beginning of your experiment. Then, depending on your condition you select a random image store it in a variable (e.g. var.pair and then cue_[pair].jpg should be fine.

There are also other ways to do that.

Does that help?
Eduard