Triggering and measuring neural response indicative of inhibition in humans during conversations with virtual humans

Abstract

The aim of this PhD was to determine if a confrontational virtual human can evoke a response in the prefrontal cortex, indicative of inhibiting an antisocial response. It follows previous studies by Aleksandra Landowska (2018) and Schilbach (2016) demonstrating that a prefrontal cortex response indicative of inhibition can be evoked by a virtual environment. The test scenario was a conversation about Brexit, the United Kingdom leaving the European Union. This was used in three experiments which varied in level of immersivity of the interface and iteratively tweaked methods. A virtual reality head-mounted display (HMD) was adopted in the first experiment, a 50-inch display monitor was adopted in the second experiment, while the third experiment was carried out in an immersive suite. The independent variable in the experiments was the friendliness of the virtual human confederates. fNIRS was used to measure changes in haemoglobin in the medial and dorsolateral prefrontal cortex. Video recordings were taken to capture possible behavioural evidence that may be associated with inhibition. The friendliness of the virtual human was measured using the likeability section of the Godspeed Questionnaire series. This may be the first study to use functional near infrared spectroscopy (fNIRS) to measure response to virtual humans; previous studies have used functional magnetic resonance imaging (fMRI), which provides a less natural experience and is not conducive to non-verbal communication. The results from the first experiment suggest an effect emanating from prior experience with VR and gaming. Consequently, participants were grouped into two, with G1 representing the group with prior VR and gaming experience and G2 representing the group with no VR and gaming experience. Increased activation was found in the dorsolateral prefrontal cortex (DLPFC) during conversation with the confrontational (unfriendly) virtual human confederate for G2, in line with similar studies of emotional regulation. G1, on the other hand, showed increased activation in the medial prefrontal cortex (MPFC) during the conversation with the friendly virtual human confederate. The second experiment which was aimed at validating the outcome of the first experiment also showed an effect emanating from prior experience with VR and gaming. The results suggest increased activation in the MPFC for G1 and increased activation in the MPFC and DLPFC for G2 during the conversation with the friendly virtual human confederate in both groups. The third experiment showed increased activation in the DLPFC during the conversation with the unfriendly virtual human confederate across participants. Furthermore, head-mounted displays complicated data capture with the fNIRS; a problem alleviated by screen or projection-based approaches. Although all the experiments in this research targeted healthy subjects, the outcome may be of interest to health professionals and technology providers interested in mental deficits relating to antisocial behaviours. It also finds potential application in mental health illness such as PTSD and autism where inhibitory responses are impaire