## 2 Case Study: Digitizing Human Emotions
### EEG Databases for Emotion Recognition
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Dataset** & **Participants** & **Clips** & **EEG Channels** & **Emotions** & **Sampling Frequency** \\ \hline DEAP & 32 & 40 & 32 & \begin{tabular}{c} Valence \\ Arousal \\ Dominance \\ \end{tabular} & \begin{tabular}{c} 512 Hz–down \\ sampled to \\ 128 Hz \\ \end{tabular} \\ \hline SEED-IV & 15 & 15 & 62 & \begin{tabular}{c} Valence \\ Arousal \\ Dominance \\ \end{tabular} & \begin{tabular}{c} 200 Hz–down \\ \\ \end{tabular} \\ \hline DREAMER & 23 & 18 & 14 & \begin{tabular}{c} Valence \\ Arousal \\ Dominance \\ \end{tabular} & N/A \\ \hline AMIGOS & \begin{tabular}{c} 40 Short \\ Experiment \\ 37 Long \\ Experiment \\ \end{tabular} & 4 Long & 14 & \begin{tabular}{c} Valence \\ Arousal \\ Dominance \\ \end{tabular} & N/A \\ \hline MAHNOB HCI & 30 & \begin{tabular}{c} Exp 1: 20 clips \\ Exp 2: \\ 28 images \\ \end{tabular} & 32 & \
\begin{tabular}{c} Valence \\ Arousal \\ \end{tabular} & 256 Hz \\ \hline MPED & 23 & 28 & 62 &
\begin{tabular}{c} Joy \\ Funny \\ Neutral \\ \end{tabular} & 1000 Hz \\ \end{tabular}
\end{table} 
Table 2: Comparison among EEG datasets in terms of participants, clips, channels, emotions, and frequencies. of the left pinky finger's body temperature and GSR, along with observations of facial expressions, eye movements, mouth shapes, and lip expressions [80]. The SEED IV EEG database is an extensive collection featuring EEG recordings from 15 subjects who engaged in 24 distinct mental activities or tasks. These recordings were captured using the Neuroscan SynAmps 2 amplifier, coupled with a 62-channel high-resolution EEG cap. Each participant underwent three sessions. The EEG data include responses to a range of auditory, visual, and somatosensory stimuli, and also include eye movement information [67; 81]. The Dreamer EEG database features EEG recordings from 14 channels of 23 healthy adults, aged 22-33. These participants were exposed to 18 different video clips, during which their brain's electrical activity was recorded using an EMOTIV EPOC headset. The data were initially collected at a sampling rate of 256 Hz and subsequently downsampled to 128 Hz for analysis [82]. The AMIGOS dataset serves as a significant resource for investigating the effects of visual media on group dynamics, emotional states, and mood. It is particularly useful for exploring how emotions (like positivity and arousal) manifest in brain activity and for studying the neural mechanisms influencing individual and group behaviors. This dataset involves physiological recordings from multiple body sites, including EEG, electrocardiography (ECG), and galvanic skin response (GSR). These recordings are beneficial for research in emotion regulation, attention, and affective neuroscience. The data were collected through two separate experiments. In the first experiment, EEG signals were recorded from 40 participants as they watched 16 short video clips, each less than 250 s in duration. The second experiment involved EEG recordings from 37 participants, who were also part of the first experiment, as they viewed four longer video clips, each exceeding 14 min. In both experiments, the same 14 channels from the EPOC headset were utilized for recordings [83]. The MAHNOB-HCI database is highly suitable for researchers exploring the impact of visual media on human emotions. It comprises EEG recordings from 27 healthy subjects, including both males and females, who took part in two distinct experiments. In the first experiment, the participants watched 20 short video clips, while in the second experiment, they were exposed to a combination of images and videos (28 images and 14 videos). The EEG data were gathered using 32 channels, and additional psychophysiological data, such  
Figure 5: Three emotion-scaling axes superimposed on the standard self-assessment manikin system (SAM). as facial expressions and heart rate (HR), were simultaneously recorded.