Yoked design

Hi,

I want to design a conditioning study where the response times for each stimulus on an operant conditioning task are recorded and people in the classical conditioning condition are exposed to each stimulus for exactly the same duration. That is, for each person in the operant conditioning task, I want a yoked classical conditioning participant who sees the stimulus for the same duration.
Do I need a custom item for this?

The only way I can think of to do this would be to manually enter the RTs from one subject as display times for another. This would be pretty easy in DirectRT as you could just copy the RT data column into the TIME column of the yoked subject's input file. You could do it with MediaLab, it's just that the ML input files are vertical whereas the data files horizontal (one row per subject). This would be a one cell at a time sort of thing. There are some ways to make that more efficient--if you want I can elaborate.