Online First 2023-11-27

Feeling of co-presence in VR depends on the realism of virtual agents. Our study explores how three dimensions of realism - visual appearance, behavior, and interactability - affect co-presence and Orienting Response (OR), measured using heart rate (HR) and skin conductance response (SCR). Moreover, we test whether HR and SCR can be used as measures of psychological concepts that describe virtual interactions like co-presence. Fourty-five participants passively viewed virtual characters while their HR and SCR were recorded. Afterwards participants assessed the experience of interacting with the virtual agents. The interactability of the virtual characters increased co-presence, and so did heightened appearance realism, but only when the level of behavioral realism was high. High visual and behavioral realism led to increase in SCR while visual realism alone evoked deeper HR deceleration. Nonetheless, neither SCR nor HR correlated with any psychological concepts that describe virtual interactions. In conclusion, realism can increase both the co-presence and magnitude of the OR, yet physiological indices can not reliably gauge the experience of interactions with virtual characters.