## 4 Performance Evaluation
### Exploring the Design of Pepita
#### 4.1.1 Questionnaire Overview  
Different robots and devices have been designed to be hugged, but one common feature is the presence of arms. Pepita has a simple appearance, and we wanted to understand how it was perceived based on its appearance. From the reviewed huggable robots, those with the appearance of a popular cartoon character (e.g., Disney characters) and ones with a repeated type of appearance (e.g., teddy bear) were excluded from the comparison with Pepita. Therefore, we chose three huggable robots to compare to Pepita (Figure 5), including one huggable robot with an expressive face [29], one huggable robot with a simple appearance and no face [57], and one robot with the familiar appearance of a teddy bear [9]. In this way, we attempted to determine whether aspects like the presence of a face and a familiar body shape affected the participant's selections. The participants were presented with a photo of each robot and asked to rate the following statements using a 5-point scale: (1) It looks huggable, (2) It looks easy to hug, and (3) It looks appealing to hug. The order of the pictures was balanced among the number of participants to avoid an order effect. The second part of the questionnaire explored the modalities used by robots to convey affective expressions visually. We compared two categories: facial expressions using mechanical faces ([PERSON] [32] and Probo [31]) and facial expressions using a display ([PERSON] [11] and Pepita [58]). Considering we need video stimulus for these items, robots that fall in this category and that had video available to the public were selected. Participants were asked to watch four videos in succession showing a robot displaying happy and sad expressions. The order of these videos was balanced to avoid an order effect. They were presented one at a time, but the participants were freely allowed to replay them. After watching the videos, the participants were presented with a reference photo of each robot that appeared in the videos (Figure 5). Using a 5-point scale, the participants rated the following statement:  
Based on your first impression, express using the following scale how acceptable you find the robot's expressions of emotions? The third part was related to exploring the first impression people had of the device. Along with an online questionnaire, we showed the participants a video of a person interacting with Pepita. In this  
Figure 5: Photos used in the questionnaire to compare huggable robots according to the appearance: (**a**) The Hug; (**b**) Probo; (**c**) The Huggable and (**d**) Pepita. Photos used in the questionnaire to compare different robot’s emotional expressions. Expressions made by display: (**e**) [PERSON] and (**g**) [PERSON]. Expressions made by mechanical face: (**f**) [PERSON] and (**h**) [PERSON]. way, we introduced the concept of [PERSON] to each participant. In the video, [PERSON] is on a sofa showing an avatar with a sad expression. Then, the person in the video takes the device and hugs it. After being hugged, [PERSON] changes the avatar to one with a happy expression. To minimize the context effect, we did not show the facial expressions of the person in the video but focused on the robot displaying its functions. After watching the video, the participants were presented with a photo of [PERSON] (Figure 1) and were asked to express their impressions using a semantic differential structure with a 7-point scale. Since a single question evaluates this item, a 7-point scale was chosen to obtain more information. The paired words selected to describe Pepita are commonly used to evaluate social robots using this structure, and it was applied following an already existing methodology [59]. Additionally, we wanted to collect some qualitative data about the participant's impressions of the robot, for which we asked an open-ended question to determine which features of Pepita positively or negatively impacted their answers.