# Asian Affective and Emotional State (A2 ES) Dataset of ECG and PPG for Affective Computing Research
## 3 Data Collection Protocol
### Emotion Annotation and Stimuli Selection
It is a wrist-worn activity and heart-rate monitor that makes use of a maxim analogue front-end (AFE), accelerometer, optical sensors, and an internal algorithm. The band is shown in Figure 5. When collecting the signals from the ECGs, the subject was instructed to start the recording only when they began to feel the emotion. This was because an ECG has a limitation of one minute as a maximum length. As for PPG, the signals were recorded continuously while the video played. Figure 4: AliveCor Kardia Mobile device and its application. Figure 3: The self-assessment form prepared in Google Forms. Figure 6 shows the percentage of the data distribution between the targeted emotion and real samples. The targeted happy, sad, anger, fear, disgust, and surprise data were equally distributed at 12%. Neutral was considered as the absence of any particular emotion, and the targeted sample size percentage was larger at 28%. The real samples based on the participants' feedback had a size for neutral of 27%. In the real data distribution, happiness had the highest sample compared to the other five discrete emotions, with an extra 8%, while anger had the least, with only 8% of the total data. The reason for such an imbalance is that some emotions, such as anger and sadness, are typically harder to trigger by only watching videos. Another reason for the slight imbalance is because different persons have different perspectives when dealing with stimuli. Table 2 shows the number of the subjects' responses towards each video. As can be observed, perspective differences existed among the participants. Additionally, some participants experienced contradictory emotions that were opposed to the targeted emotion. Video 4, for example, failed to induce the targeted emotion of happiness in the majority of the participants. The video concerns the anticipation of a happy ending in a well-known fictional movie; the popularity of this movie, as well as the suspense element of the clip, contributed to a greater number of participants selecting neutral and surprise. In another case involving videos 18 and 20, they were supposed to conjure sadness in the viewers, and the majority of the subjects reported feeling happy instead. Video 18 portrays a pitful situation of a young man who encounters difficulties, but the act of kindness shown by the strangers towards him may have caused the viewers to feel happy instead of sad. Video 20  
Figure 5: Maxim PPG Band. Figure 6: Data distribution of the emotion labels. shows a collection of heart-warming father-daughter relationships in the context of the latter's wedding day. Although the scene is touching and sad, most viewers perceived it as happiness, because the situations take place on a wedding day, which is typically perceived as a happy occasion. In occasions where the targeted emotion was different than the participants' feedback, this study considered the individual self-assessments as the data labels. Meanwhile, disgust had the most similar majority votes, with all three of the videos managing to obtain more than 40 subjects (out of 48) experiencing the targeted emotion. Video 15 recorded the highest number of participants experiencing the targeted disgust emotion (46), and only two participants experienced other emotions, with one participant reporting being not affected by the video (neutral), while another participant felt fear after watching the video. This video depicted a girl eating frogs. For the surprise, fear, and anger videos, the majority of the votes in the self-assessments were similar to the targeted emotions. Videos 1, 5, 9, 13, 17, 21, and 25 were considered neutral, and they were played between other targeted emotion videos to regulate the participants' emotions and lower the intensity of the emotion felt from the previous videos. Hence, some of the subjects might have experienced a residual emotion from the previous videos, causing them to label the presence of emotions instead of neutrality.