small bugfix in utils.load_data
small bugfix in utils.load_data

some fields may have multiple values which build off the same
stem (e.g., mat_type stim_class and stim_class_5_blanks), so we use this
to make sure we grab only the one that has an exact match

billbrod/spatial-frequency-preferences,billbrod/spatial-frequency-preferences,billbrod/spatial-frequency-preferences