Precise information about where the EEG signals were recorded seems to be an obligatory requirement for any responsible researcher, particularly if these signals are used to infer brain functions. The level of required precision depends on the (implicit) head model, which may be as simple as the 10–20 system and its expansions (e.g., Jurcak et al., 2007; Oostenveld and Praamstra, 2001). Spherical head models appear to be appropriate for many SL applications, particularly for the typical range of spatial frequencies available from a finite number of electrodes (Yao, 2002b).
