The overall goal of our research is to develop a system of intelligent multimodal affective pedagogical agents that are effective for different types of learners (Adamo et al., 2021). While most of the research on pedagogical agents tends to focus on the cognitive aspects of online learning and instruction, this project explores the less-studied role of affective (or emotional) factors. We aim to design believable animated agents that can convey realistic, natural emotions through speech, facial expressions, and body gestures and that can react to the students’ detected emotional states with emotional intelligence. Within the context of this goal, the specific objective of the work reported in the paper was to examine the extent to which the agents’ facial micro-expressions affect students’ perception of the agents’ emotions and their naturalness. Micro-expressions are very brief facial expressions that occur when a person either deliberately or unconsciously conceals an emotion being felt (Ekman &Friesen, 1969). Our assumption is that if the animated agents display facial micro expressions in addition to macro expressions, they will convey higher expressive richness and naturalness to the viewer, as “the agents can possess two emotional streams, one based on interaction with the viewer and the other based on their own internal state, or situation” (Queiroz et al. 2014, p.2).The work reported in the paper involved two studies with human subjects. The objectives of the first study were to examine whether people can recognize micro-expressions (in isolation) in animated agents, and whether there are differences in recognition based on the agent’s visual style (e.g., stylized versus realistic). The objectives of the second study were to investigate whether people can recognize the animated agents’ micro-expressions when integrated with macro-expressions, the extent to which the presence of micro + macro-expressions affect the perceived expressivity and naturalness of the animated agents, the extent to which exaggerating the micro expressions, e.g. increasing the amplitude of the animated facial displacements affects emotion recognition and perceived agent naturalness and emotional expressivity, and whether there are differences based on the agent’s design characteristics. In the first study, 15 participants watched eight micro-expression animations representing four different emotions (happy, sad, fear, surprised). Four animations featured a stylized agent and four a realistic agent. For each animation, subjects were asked to identify the agent’s emotion conveyed by the micro-expression. In the second study, 234 participants watched three sets of eight animation clips (24 clips in total, 12 clips per agent). Four animations for each agent featured the character performing macro-expressions only, four animations for each agent featured the character performing macro- + micro-expressions without exaggeration, and four animations for each agent featured the agent performing macro + micro-expressions with exaggeration. Participants were asked to recognize the true emotion of the agent and rate the emotional expressivity ad naturalness of the agent in each clip using a 5-point Likert scale. We have collected all the data and completed the statistical analysis. Findings and discussion, implications for research and practice, and suggestions for future work will be reported in the full paper. ReferencesAdamo N., Benes, B., Mayer, R., Lei, X., Meyer, Z., &Lawson, A. (2021). Multimodal Affective Pedagogical Agents for Different Types of Learners. In: Russo D., Ahram T., Karwowski W., Di Bucchianico G., Taiar R. (eds) Intelligent Human Systems Integration 2021. IHSI 2021. Advances in Intelligent Systems and Computing, 1322. Springer, Cham. https://doi.org/10.1007/978-3-030-68017-6_33Ekman, P., &Friesen, W. V. (1969, February). Nonverbal leakage and clues to deception. Psychiatry, 32(1), 88–106. https://doi.org/10.1080/00332747.1969.11023575 Queiroz, R. B., Musse, S. R., &Badler, N. I. (2014). Investigating Macroexpressions and Microexpressions in Computer Graphics Animated Faces. Presence, 23(2), 191-208. http://dx.doi.org/10.1162/
Inferring emotions from others’ non-verbal behavior is a pervasive and fundamental task in social interactions. Typically, real-life encounters imply the co-location of interactants, i.e., their embodiment within a shared spatial-temporal continuum in which the trajectories of the interaction partner’s Expressive Body Movement (EBM) create mutual social affordances. Shared Virtual Environments (SVEs) and Virtual Characters (VCs) are increasingly used to study social perception, allowing to reconcile experimental stimulus control with ecological validity. However, it remains unclear whether display modalities that enable co-presence have an impact on observers responses to VCs’ expressive behaviors. Drawing upon ecological approaches to social perception, we reasoned that sharing the space with a VC should amplify affordances as compared to a screen display, and consequently alter observers’ perceptions of EBM in terms of judgment certainty, hit rates, perceived expressive qualities (arousal and valence), and resulting approach and avoidance tendencies. In a between-subject design, we compared the perception of 54 10-s animations of VCs performing three daily activities (painting, mopping, sanding) in three emotional states (angry, happy, sad)—either displayed in 3D as a co-located VC moving in shared space, or as a 2D replay on a screen that was also placed in the SVEs. Results confirm the effective experimental control of the variable of interest, showing that perceived co-presence was significantly affected by the display modality, while perceived realism and immersion showed no difference. Spatial presence and social presence showed marginal effects. Results suggest that the display modality had a minimal effect on emotion perception. A weak effect was found for the expression “happy,” for which unbiased hit rates were higher in the 3D condition. Importantly, low hit rates were observed for all three emotion categories. However, observers judgments significantly correlated for category assignment and across all rating dimensions, indicating universal decoding principles. While category assignment was erroneous, though, ratings of valence and arousal were consistent with expectations derived from emotion theory. The study demonstrates the value of animated VCs in emotion perception studies and raises new questions regarding the validity of category-based emotion recognition measures.
more » « less- Award ID(s):
- 1907807
- NSF-PAR ID:
- 10477502
- Publisher / Repository:
- Frontiers
- Date Published:
- Journal Name:
- Frontiers in Virtual Reality
- Volume:
- 4
- ISSN:
- 2673-4192
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/frvir.2023.1032510
