What do I need to work with ES32?
I'm glad you ask. You don't need that much, but some things are necessary.
Of course, you need a PC. It must be running a Microsoft OS. Anything since Windows 95 should do. But ES32 is only tested on Windows 98, 98 SE, ME, and 2000. I don't see any reason for it not to work on XP, but I can't guarantee anything. The hardware shouldn't matter much. Of course it will run faster on faster hardware and the more memory your system has, the better. Since ES32 is designed to let you visually explore your data, you should have a screen resolution of at least 1024 × 768.
Next stop: the data. Obviously you need data because ES32 feeds on data.
- .EEG files
- .DAT files
ES32 currently has no idea how to do anything at all with continous files. Thus you will have to provide epoched data in the form of .EEG files, just like Neuroscan's software will produce them for you.
Along with each .EEG files, you will also have to provide a little ASCII file (I simply call them .DAT files here; the actual name doesn't matter). The format of these files is quite simple. There is a header of 20 lines, there is a footer of 3 lines, and sadwiched between these two is one line per sweep. Each of these lines contains 5 columns. The most important columns (in fact the only columns ES32 will take a look at) are columns 3, 4, and 5. Column three contains the type code the lets you (and your software) determine which stimulus condition was presented in the current sweep. Column 4 contains information about the correctness of the subject's response, e.g. a "1" for a correct response and a "0" for an error. Finally, column 5 contains the reaction time in seconds.
Here is an example: the first 8 trials of a real subject:
1 2 13 1 0.512 2 2 13 1 0.573 3 1 3 1 0.410 4 2 14 1 0.490 5 1 7 1 0.510 6 2 13 1 0.390 7 2 16 1 0.422 8 1 7 1 0.609
ES32 tries to make everything as easy as possible for you. E.g. when you tell ES32 to average a bunch of files (yes, you don't have to average them one by one), ES32 simply accepts a list of .EEG files and a list of .DAT files. Of course, it needs some way to map both file types. The magic is done with correct file names. Suppose you have three subjects, then simply name the corresponding files sub1.eeg and sub1.dat, sub2.eeg and sub2.dat, and sub3.eeg and sub4.dat. Instead of literal .DAT files you could also use files called sub.1, sub.2, and sub.3. The point is that ES32 needs the subject's number in both the file name of the .EEG file and the file name of the .DAT file.