The uncanny valley effect is the emotional response that occurs when a not-quite-perfectly-human entity (such as a robot, animation or doll) triggers feelings of eeriness, discomfort or repulsion. A recent study from the University of Hamburg found that this effect also triggers physiological reactions, particularly immune responses.

Three groups of virtual agents were used in the study: cartoon characters, realistic avatars and avatars with subtle deviations from human appearance that were perceived as uncanny. Subjects interacted with these avatars in a virtual reality environment. Before and after the interaction, saliva samples were taken from the subjects to measure the concentration of immunoglobulin A (sIgA), an antibody that plays a key role in mucosal immunity.

The results showed that only the group of uncanny avatars elicited a significant increase in sIgA concentration. This suggests that discomfort toward these avatars can trigger an automatic immune response. Interestingly, this increase did not correlate with conscious evaluations of the avatars, suggesting that the immune response was triggered unconsciously and instinctively.

The researchers interpreted these results in the context of the pathogen-avoidance hypothesis. Accordingly, the human brain has developed in order to recognize subtle references to possible diseases and activate corresponding protective mechanisms. Avatars that appear uncanny could therefore be perceived as potential sources of disease, which explains the immune response triggered.

The study provides new insights into the physiological effects of the uncanny valley effect and expands the understanding of how people react to human-like digital characters. The results could have an impact on the design of avatars in virtual reality applications, especially in areas such as health communication or psychological training.