Multiple superlab stimulus folders

Apparently when you set up an experiment in Superlab that uses external stimulus files or folders, it saves two pointers to the files: the absolute path at the time the file or folder was specified, and the file or folder relative to the scenario file when it was saved. In fact, it appears that sometimeis if you use "save as" within superlab to save a scenario, it recomputes the relative address(es) using the new scenario location. Therefore, as long as the relative path points to folders and/or files that exist, and that the absolute path does NOT exist, things will work. However, this latter approach will not always work

However, if the absolute path is valid, then those files will be used instead of the local relative path, and the wrong stimuli will be presented. What is needed is some way to relocate the scenario file, relative to a certain version of the stimulus files.

Say for example you have 25 subject folders named 01-25, and they are all "sister" folders, that is, subfolders of the same superordinate folder. You might think that if you set up the scenario and stored the scenario in subject 01's folder, you could then copy the scenario into each of the others and use their stimulus set-up. But since the absolute address of subject 01's stimuli would still exist, I strongly suspect that they would be used instead of the relative address. What is needed is some way to relocate the paths in the scenario file so that they point to the new location.

If superlab can't find the stimuli, it asks the experimenter where they are. This could cause some fairly minor problems, but the larger issue is when it does find them, in the wrong place.

It turns out that it is possible simply to overlay the absolute paths (or as many of them as you want to relativize) with a sequence of X's of the same length, using some method such as a binary editor like bbe(1). Superlab is quite content to use the relative address. Note that if you should happen to save the scenario, new absolute addresses will be written in there.

It would be better if there were some way to identify the absolute addresses automatically, but since they can be located almost anywhere, that's a bit tricky. There are some other paths in there, such as the default logfile location. Maybe the best way is simply to specify them as part of the setup, since they will be known then, and do the overlay as part of building the project.

UPDATE

One very important lesson: take the time to do all development of superlab scenarios in a directory hierarchy that matches how it will eventually be installed. This is a little less convenient in the beginning, but pays off hugely later on.