## 3 Results
### Distal Participant Data Analysis  
The second part of our analyses focused on the ratings given by the participants on both authenticity and emotional intensity. Across all stimuli, the reliability of our participants' ratings was high, \(\alpha=0.92\) for authenticity and \(\alpha=0.93\) for intensity. Participants were grouped together into two categories, music-lovers and musicians, based on their responses for the musical habits questionnaires [77]. No significant difference in means was observed between groups for both authenticity (\(M_{musicians}=43.155\), \(SD_{musicians}=25.28\), \(M_{music-lovers}=46.217\), \(SD_{music-lovers}=23.98\), \(t(819)=-1.829\), \(p=0.067\), \(d=-0.12\)) and intensity (\(M_{musicians}=42.308\), \(SD_{musicians}=24.598\), \(M_{music-lovers}=45.314\), \(SD_{music-lovers}=22.059\), \(t(819)=-1.89\), \(p=0.059\), \(d=-0.13\)). The difference between both groups is marginal. Moreover, this difference is trivial due to the very small effect size associated with the \(p\)-value being influenced by the large number of trials (see [PERSON]'s guideline [78]). We thus concluded that an analysis could be performed on the dataset as a whole. Responses for authenticity and emotional intensity were also highly correlated (\(r=0.727\)). This is noticeable with the relatively similar outcomes of the evaluated models. This next section focuses on separate model  
Figure 2: Impact of the interaction of the expressiveness and the presence of an audience on body features (deadpan: DP, projected: PROJ, and exaggerated: EXAG): (**A**) Kinetic energy (red); (**B**) Body Twist Index (green); and (**C**) Metrical centroid (blue). (* \(p<0.05\), ** \(p<0.01\), *** \(p<0.001\)). estimations for both authenticity and emotional intensity. Two different models were implemented. First, we estimated both dependent variables using both the expressive intent and the social factor. Second, we explored the impact of the variation of both motion and acoustic features on the perceived emotional intensity and authenticity. 2.1 Interaction Effect of the Expressive Intents and the Presence of an Audience on Perceived Authenticity and Emotional Intensity  
Two models were computed to estimate the influence of the expressive intents and the presence of an audience, respectively, on the perceived authenticity and the emotional intensity. The first model estimated the perceived emotional intensity using the different categories of expressive intent and the presence of an audience, as well as the interaction, as fixed effects, and with the participants and the musician at play as random effects (a model computing only the main effect and not the interaction is not presented in this article based on the principle of marginality; however, graphs related to such model can be found in the Supplementary Materials (Appendix Figure A2)). This model was significantly better than a model using only the main fixed effects, no interaction, and the same random effects (intensity: \(\chi^{2}(3,N_{trials}=875)=12.036\), \(p=0.01\), \(AIC=7640.6\), \(BIC=7688.4\), \(R_{m}^{2}=0.08\), \(R_{c}^{2}=0.42\)). The second model estimated the perceived authenticity using the same fixed and random effects. This model was significantly better than a model using only the main fixed effects, no interaction, and the same random effects (authenticity: \(\chi^{2}(3,N_{trials}=875)=18.026\), \(p=8.68\times 10^{-4}\), \(AIC=7738.7\), \(BIC=7786.4\), \(R_{m}^{2}=0.11\), \(R_{c}^{2}=0.42\)). Both perceived authenticity and emotional intensity increased significantly with every increment of the musicians' expressiveness in the case of the absence of audience (intensity: \(\chi^{2}_{EmoInt,DP/Proj,Absence}(1,N_{trials}=875)=22.909\), \(p=1.69\times 10^{-6}\), \(\chi^{2}_{EmoInt,Proj/Exag,Absence}(1,N_{trials}=875)=13.765\), \(p=0.0002\), and authenticity: \(\chi^{2}_{Auth,DP/Proj,Absence}(1,N_{trials}=875)=33.624\), \(p=6.6\times 10^{-9}\), \(\chi^{2}_{Auth,Proj/Exag,Absence}(1,N_{trials}=875)=11.009\), \(p=0.0009\)) (Figure 3).