## 4 Performance Evaluation
### Affective Feedback Using Projected Avatars
#### 4.5.1 Questionnaire Overview  
In this study, we had the goal of answering the following questions:  
1. Can each visual element displayed by the robotic device represent the intended affective expression? 2. Comparing the LED and projected avatars, which is more efficient at representing the selected affective expression? 3. When the robot is projecting avatars, is it perceived as one entity (the robot and its avatar) or two separate entities (a robot and an avatar)? In the experiment described next, we compared the effect of colored lights with the effect of projected avatars when they were used to convey the robot's affective expressions. To evaluate the use of avatars in this application, we developed an online questionnaire using the service provided by [56]. The complete questionnaire can be found in Appendix B. Twenty-six participants who were not familiar with the robot (18 males and 8 females, age 26.9 \(\pm\) 3.7 on average) took this questionnaire. The nationalities of the participants were grouped as: North America = 1, Central America = 3, South America = 15, Europe = 1 and, Asia = 1. The participant's cultural background is a factor that can potentially impact the perception of emotions represented by color [60; 61]. In the literature, common colors are combined with other parameters to represent a robot's emotional expressions [36; 39; 62], and, for this reason, the cultural aspect is not necessarily controlled as the feedback perception is far from being only related to colors. Since the purpose of this experiment is not to evaluate the effect of the cultural background on the perception of the robot, there was no restriction regarding nationality to join this experiment. Participants were contacted via social network and receive the access link via email. The questionnaire was not open but could only be accessed after receiving an invitation. The questionnaire consisted of two sets of two videos each, followed by questions. The order of the videos was counterbalanced to reduce the order effect. Two of the videos showed the robot projecting an avatar with emotional facial expressions (Figure 12a,b), and the other two showed the robot displaying LED color patterns (Figure 12c,d). Each participant received one of the combinations, and the combinations were proportionally balanced among the group of participants. The videos presented the robot displaying one type of visual feedback without being contextualized by the environment or interaction. A previous study showed evidence that the context could affect the participant's recognition of the robot's expressions [63]. For this reason, we avoided influencing the participant's choices by adding elements related to interaction, such as by showing the happy state after hugging or the sad one after hitting. In this questionnaire, we attempted to evaluate only the perception of the visual elements. After watching the videos, the participants were asked to rate the following statements using a 5-point rating scale:  
* In my general impression, I consider that the perceived behavior of the robot makes reference to a happy-like behavior. * In my general impression, I consider that the perceived behavior of the robot makes reference to a sad-like behavior. The second part of the questionnaire was related to the perception of the robot's embodiment. Because we were using two types of embodiment (the projected robot and physical robot), we intended to clarify the entity for which the participants perceived the affective expressions. The concept of using multimodal interfaces to benefit from different types of embodiment has been explored in the past [64], where an avatar was used as a complement of a physical robot, and they were combined into one entity. The avatar was designed with an appearance similar to the physical robot, and it was implemented using a migration system, which involved having either the avatar or robot active at any given time.