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Objective: Uncanniness plays a vital role in interactions with humans and artificial agents. Previous studies have shown that uncanniness is caused by a higher sensitivity to deviation or atypicality in specialized categories, such as faces or facial expressions, marked by configural processing. We hypothesized that asynchrony, understood as a temporal deviation in facial expression, could cause uncanniness in the facial expression. We also hypothesized that the effect of asynchrony could be disrupted through inversion., Results: Sixty-four participants rated the uncanniness of synchronous or asynchronous dynamic face emotion expressions of human, android, or computer-generated (CG) actors, presented either upright or inverted. Asynchrony vs. synchrony expressions increased uncanniness for all upright expressions except for CG angry expressions. Inverted compared with upright presentations produced less evident asynchrony effects for human angry and android happy expressions. These results suggest that asynchrony can cause dynamic expressions to appear uncanny, which is related to configural processing but different across agents., (© 2023. The Author(s).)

Humanlike androids can function as social agents in social situations and in experimental research. While some androids can imitate facial emotion expressions, it is unclear whether their expressions tap the same processing mechanisms utilized in human expression processing, for example configural processing. In this study, the effects of global inversion and asynchrony between facial features as configuration manipulations were compared in android and human dynamic emotion expressions. Seventy-five participants rated (1) angry and happy emotion recognition and (2) arousal and valence ratings of upright or inverted, synchronous or asynchronous, android or human agent dynamic emotion expressions. Asynchrony in dynamic expressions significantly decreased all ratings (except valence in angry expressions) in all human expressions, but did not affect android expressions. Inversion did not affect any measures regardless of agent type. These results suggest that dynamic facial expressions are processed in a synchrony-based configural manner for humans, but not for androids., (© 2023. Springer Nature Limited.)

The "thinking face" is a facial signal used to convey being in thought. For androids, the thinking face may be important to achieve natural human–robot interaction. However, the facial pattern necessary for portraying the thinking face remains unclear and has not yet been investigated in androids. The current study aims to (a) identify the facial patterns when people are engaged in answering complex questions (i.e., thinking face) and (b) clarify whether implementing the observed thinking faces in an android can facilitate natural human–robot interaction. In Study 1, we analyze the facial movements of 40 participants after they are prompted with difficult questions and indicate five facial patterns that corresponded to thinking faces. In Study 2, we further focus on the pattern of furrowing of the brows and narrowing of the eyes among the observed thinking facial patterns and implement this pattern in an android. The results show that thinking faces enhance the perception of being in thought, genuineness, human-likeness, and appropriateness in androids while decreasing eeriness. The free-description data also revealed that negative emotions are attributed to the thinking face. In Study 3, we compared the thinking vs. neutral faces in a question–answer situation. The results showed that the android's thinking face facilitated the perception of being in thought and human-likeness. These findings suggest that the thinking face of androids can facilitate natural human–robot interaction. [ABSTRACT FROM AUTHOR]

The uncanny valley describes the typically nonlinear relation between the esthetic appeal of artificial entities and their human likeness. The effect has been attributed to specialized (configural) processing that increases sensitivity to deviations from human norms. We investigate this effect in computer-generated, humanlike android and human faces using dynamic facial expressions. Angry and happy expressions with varying degrees of synchrony were presented upright and inverted and rated on their eeriness, strangeness, and human likeness. A sigmoidal function of human likeness and uncanniness ("uncanny slope") was found for upright expressions and a linear relation for inverted faces. While the function is not indicative of an uncanny valley, the results support the view that configural processing moderates the effect of human likeness on uncanniness and extend its role to dynamic facial expressions. [ABSTRACT FROM AUTHOR]

The relationship between artificial entities' human likeness and aesthetic preference is thought to be best modelled by an N -shaped cubic "uncanny valley" function, which however suffers from conceptual criticisms and lack of parsimony. Here it is argued that uncanniness effects may instead be modelled by a linear function of deviation moderated by perceptual specialization. The two models are compared in an experiment with five incrementally distorted face types (cartoon, CG, drawing, real, robot). Recognition performance for upright and inverted faces were used as a specialization measure. Specialization significantly moderated the linear effect of distortion on uncanniness, and could explain the data better than a conventional uncanny valley. The uncanny valley may thus be better understood as a moderated linear function of specialization sensitizing the uncanniness of deviating stimuli. This simpler yet more accurate model is compatible with neurocognitive theories and can explain uncanniness effects beyond the conventional uncanny valley. • Face realism affects both specialization and deviation sensitivity. • Specialization moderates the effect of deviation on uncanniness in faces. • This moderated linear function explains uncanniness better than a cubic "uncanny valley" model. • Parsimony, accuracy, generalizability, and plausibility of the moderation model over the uncanny valley are discussed. [ABSTRACT FROM AUTHOR]