The researchers compared four VS patients with thirteen healthy controls. All underwent fMRI scans while viewing pictures of familiar and unfamiliar faces, including their own faces. In addition, all participants were asked to imagine a parent’s face.
Finally, as with all fMRI studies, the authors have to make sure their data passes the ‘dead salmon’ test. If you don’t make sure you analyze your fMRI data properly, even dead salmon will respond to pictures.
Sharon H, Pasternak Y, Ben Simon E, Gruberger M, Giladi N, Krimchanski BZ, Hassin D, & Hendler T (2013). Emotional processing of personally familiar faces in the vegetative state. PloS one, 8 (9) PMID: 24086365.