To trust or not to Trust? Face and voice modulation of virtual avatars

Objective: This study explores the graduation of social traits in virtual characters by experimental manipulation of perceived trustworthiness with the aim to validate an existing predictive model in animated whole-body avatars. Method: We created a set of 210 animated virtual characters, for which facial features were generated according to a predictive statistical model originally developed for 2D faces. In a first online study, participants (N=34) rated mute video clips of the characters on the dimensions of trustworthiness, dominance, valence, and arousal. In a second study (N=49), vocal expressions were added to the avatars, with voice recordings manipulated on the dimension of trustworthiness by their speakers. Results: In study one, as predicted, we found a significant positive linear (t(7071)=47.67, p<.001) as well as quadratic (t(7071)=-4.76, p<.001) trend in trustworthiness ratings. We found a significant negative correlation between mean trustworthiness and arousal (=-.37, p<.001), and a positive correlation with valence (=.88, p<.001). In study two, we found a significant linear (t(4465.96)=33.91, p<.001), quadratic (t(4465.96)=-10.05, p<.001), cubic (t(4465.96)=-5.90, p<.001), quartic (t(4465.96)=4.88, p<.001) and quintic (t(4465.96)=3.20, p=.001) trend in trustworthiness ratings. Similarly to study one, we found a significant negative correlation between mean trustworthiness and arousal (=-.42, p<.001) and a positive correlation with valence (=.76, p<.001). Conclusion: We successfully showed that a multisensory graduation of social traits, originally developed for 2D stimuli, can be applied to virtually animated characters, to create a battery of animated virtual humanoid male characters. These virtual avatars have a higher ecological validity in comparison to their 2D counterparts and allow for a targeted experimental manipulation of perceived trustworthiness. The stimuli could be used for social cognition research in neurotypical and psychiatric populations.