Ongoing advances in computer graphics and robotics technologies have allowed the development of increasingly humanlike robots and computer-animated virtual characters for consumer, service, health care, entertainment, and research purposes. Such developments may come with a cost, however. The uncanny valley hypothesis (UVH) predicts that virtual characters or robots that resemble real humans too closely can elicit feelings of unease, eeriness, and lack of familiarity. Despite its importance, the validity of UVH has not yet been firmly established. The UV phenomenon is often taken for granted; for example, specific animation films are often anecdotally cited as exemplars of the uncanny valley. In contrast, empirical research has still provided inconsistent evidence for this phenomenon.
A deeper understanding of UVH is important for society for two reasons: first, it can guide the development of human-like robots and virtual characters and second, it can help us predict how individuals will react to them. Various kinds of socially interactive robots have already begun to appear for consumer, service, and health care applications. Two examples include seal-like robot PARO that is being used for therapeutic purposes and ROBEAR robot that is being used in nursing care. Purposefully human-like robots are also being developed by companies such as Hanson Robotics. In entertainment, the first attempts to create fully animated human-like cinematic actors were already made shortly after the turn of the present millennium when films such as Beowulf and The Polar Express saw their premieres. Such films met an overall negative critical reception that focused on the “uncanniness” of their highly realistic animations, and the UVH was even explicitly mentioned in some reviews. In science, virtual characters are now being used increasingly more often to replace research stimuli recorded from real humans. This is the case for example for neurocognitive experiments on affects and social cognition, in which faces and facial expressions have long served as research stimuli. Because the UVH makes a general recommendation to avoid high levels of realism and human-likeness, it is of direct relevance to all of the aforementioned applications.
This project approached the UVH mainly from the perspective of social-affective neurocognitive research; however, its results were expected to be of more general societal relevance as well. We focused mainly on computer-generated (CG) faces given the importance of faces in social interaction and the wide-spread use of CG faces in neurocognitive studies. The overall objectives of this project included assessing whether and when the UV exists and investigating the similarities and differences in the neurocognitive processing of real and CG faces.
We include the following conclusions for the action (for explanations, see the section below): i) uncanny valley phenomenon exists but it is much weaker than usually thought and strongly influenced by social factors; ii) contrary to UVH, more realistic CG faces are actually more desirable; iii) CG faces elicit different cognitive, affective, and neural processing than real faces.
