Ultimately, we hope that this paper will stimulate new perspectives in order to access and assess (self) awareness also in clinical populations such as DOC patients. A sample consisting of 14 subjects (9 females, 5 males) with age ranging from 21 to 53 (M=25.79; SD=8.17) was recorded. All volunteers were right-handed German native speakers without any recorded history of neurological disease. Participants gave written
informed consent approved by the local ethics committee and received monetary compensation for their participation. The experiment expands the SON task as introduced by Schnakers et al. (2008) and subsequently adapted in Fellinger et al. (2011). Stimuli were either spoken by a familiar (FV; subject’s close friend or family member) or unfamiliar voice (UFV; spoken by a text-to-speech algorithm, CHIR-99021 purchase CereProc®, CareProc Ltd: RG7422 in vitro “Alex”, “Gudrun”). Stimuli included the subject’s own name and five commonly used Austrian names (according to statistics Austria) matched for number of syllables and the gender of the participant. Stimuli were presented via headphones at a sound pressure level of 80 db. The task consisted of two experimental conditions: an active condition to investigate the ability to consciously follow commands and a passive listening condition
with the passive condition always preceding the active condition. Each condition consisted of 3 blocks; with each block including 13 presentations of each name (i.e., 39 presentations for each single name). In the passive condition 6 stimuli were presented with 234 repetitions in total (about 12 min), in particular, SON uttered by a familiar or unfamiliar voice and two different unfamiliar names either spoken by a familiar or an unfamiliar voice. In the active condition
only 3 different stimuli were presented (117 repetition) for about 6 min, all of them unfamiliar to participants and all uttered by a familiar voice (cf. Fig. 1). During the passive condition participants were simply asked to listen to all the names presented, while in the active condition they were asked to focus and silently count the appearance of the target name. In order to be sure that participants attended the presented stimuli experimenters clonidine controlled at the end of the experiment whether the number of targets counted by participants matched the total number of stimuli presented and controlled online for arousal fluctuations. The inter stimulus interval [ISI] lasted 2000 ms and for stimulus presentation and synchronization, the Software Presentation®, (Version 0.71; Presentation Software, Neurobehavioralsystems Inc., CA) was used. EEG was recorded with 32 Ag/AgCl sintered electrodes and head circumference matched Easycaps (EASYCAP GmbH; Herrsching Germany) placed according to the international 10–20 system.