Put caps on trials taken from a block (case 27460)

[Researcher321]

Is it possible to randomly select a block, then randomly select a trial within the block, then randomly select another block and repeat the process until the participant has went through - for example - 3 trials within each block? This would mean that once a participant has went through 3 trials for one block, a cap is put in place so that they no longer receive a trial from that block.

[jason_reed]

DirectRT can randomly select trials from an input file as long as the trials have the same positive nonzero integer in the wgr cell of that row of the input file. You can also select a subset of trials in a block by placing a trial with a value of 0 in the wgr cell of its row right after the last row of the number of desired trials. For example, lest say you have a block of 10 consecutive trials that all have the same positive nonzero integer in the wgr cell. You could randomly select 3 out of 10 trials by placing a row with a value of 0 in the wgr cell right after the third row in this block.

You could further randomize the presentation of different blocks by using the bgr feature to randomize the presentation of subset of trials. However, you would not be able to mix different trials from different blocks; all of the trials in a subset of a given block would need to presented at one time.