The relationship chart of four different fMRI data analysis cases.

<p>(A) Case WithinSub: Classifiers are trained and tested for each subject separately; (B) Case AcrossSub: Classifiers are built across subjects, that is, leaving out the complete data of one subject for testing and using the data from all other subjects for training; (C) Case AvgItem: fMRI data are averaged over items and classifiers are built across subjects on the averaged data; (D) Case AvgSub: fMRI data are averaged over subjects and classifiers are built for this “averaged subject”. For each fMRI data analysis case, if a red rectangle contains only one subject, it indicates a within-subject analysis. Otherwise, the analysis is done across subjects.