Biological postural oscillations during facial expression of pain in virtual characters modulate early and late ERP components associated with empathy: A pilot study

Abstract

There is a surge in the use of virtual characters in cognitive sciences. However, their behavioural realism remains to be perfected in order to trigger more spontaneous and socially expected reactions in users. It was recently shown that biological postural oscillations (idle motion) were a key ingredient to enhance the empathic response to its facial pain expression. The objective of this study was to examine, using electroencephalography, whether idle motion would modulate the neural response associated with empathy when viewing a pain-expressing virtual character. Twenty healthy young adults were shown video clips of a virtual character displaying a facial expression of pain while its body was either static (Still condition) or animated with pre-recorded human postural oscillations (Idle condition). Participants rated the virtual human's facial expression of pain as significantly more intense in the Idle condition compared to the Still condition. Both the early (N2-N3) and the late (rLPP) event-related potentials (ERPs) associated with distinct dimensions of empathy, affective resonance and perspective-taking, respectively, were greater in the Idle condition compared to the Still condition. These findings confirm the potential of idle motion to increase empathy for pain expressed by virtual characters. They are discussed in line with contemporary empathy models in relation to human-machine interactions.

Keywords: EEG; ERPs; Idle motion; Pain empathy; Virtual character.

Fig. 1

Left: virtual character's facial expression of pain at the beginning of the clip (AUs at 40% of maximum contraction). Middle and right: virtual character's facial expression of pain from 400 ms to 1000 ms (AUs at 60% of maximum contraction).

Fig. 2

Average time-course for event-related potentials in the Idle and Still conditions recorded at the fronto-central electrodes (C1, C2, Cz, FC1, FC2, FCz). (*p < .05).

Fig. 3

Average time course for event-related potentials in the Idle and Still conditions recorded at the centro-parietal electrodes (C1, C2, Cz, CP1, CP2, CPz).

Fig. 4

Average time course for event-related potentials in the Idle and Still conditions recorded at the right centro-parietal electrodes (C4, C6, CP4, CP6). (*p < .05).

Fig. 5

Correlation between the difference in the pain rating in the Idle and Still conditions and the difference in right late positive potential (rLPP) amplitude in the Idle and Still conditions.