Thesis - Instituto de Telecomunicações

56 CHAPTER 3. INFORMATION SOURCESEDAFor electrodermal activity measurement, a bipolar placement at the distal phalanges of themiddle and pointer fingers at the anterior side of the non-dominant hand was used. In figure3.13 the places used for electrode positioning are identified.No preparation besides the cleaning of the hand with a tissue was done. We used twoAg/AgCl contact surfaces with 8 mm diameter that were placed in the finger with the helpof a small Velcro band. The preparation guidelines were obtained from [72].In figure B.7 the EDA montage with the Velcro bands and the wiring is shown.Figure 3.13: Right hand diagram indicating electrode placement at the distal phalanges inbipolar mode.EEGThe electroencephalography signals were collected from 4 points following the 10-20 system[101] (see figure 3.14). This system uses odd numbers for the left hemisphere and even forthe right hemisphere. In the central line the locations are marked with a z. The letterscorrespond to locations in the head respectively named: C - central; F - frontal; F p - frontalpole ; O - occipital; P - parietal; and T - temporal. The locations used in our study werethe F p1 , F z , F p2 , and O z . We used a linked ears EEG montage connecting the two ears tothe ground reference.The preparation of the head was done first by identifying the positioning places andthen cleaning with an abrasive gel. The EEG electrodes were filled with conductive pasteand compressed in the identified places. A large band was positioned to cover the frontaland occipital zones supporting the electrodes.Figure B.10 shows a subject with the EEG band and the linked ears montage.