The mind minds minds: The effect of intentional stance on the neural encoding of joint attention.

Recent neuroimaging studies have observed that the neural processing of social cues from a virtual reality character appears to be affected by "intentional stance" (i.e., attributing mental states, agency, and "humanness"). However, this effect could also be explained by individual differences or perceptual effects resulting from the design of these studies. The current study used a new design that measured centro-parietal P250, P350, and N170 event-related potentials (ERPs) in 20 healthy adults while they initiated gaze-related joint attention with a virtual character ("Alan") in two conditions. In one condition, they were told that Alan was controlled by a human; in the other, they were told that he was controlled by a computer. When participants believed Alan was human, his congruent gaze shifts, which resulted in joint attention, generated significantly larger P250 ERPs than his incongruent gaze shifts. In contrast, his incongruent gaze shifts triggered significantly larger increases in P350 ERPs than his congruent gaze shifts. These findings support previous studies suggesting that intentional stance affects the neural processing of social cues from a virtual character. The outcomes also suggest the use of the P250 and P350 ERPs as objective indices of social engagement during the design of socially approachable robots and virtual agents.