Towards neural signal analysis for assessing digital character plausibility

Presence in virtual reality literature is known as the sense of "being there". A proposed structure of presence, is that it consists of two separate orthogonal illusions, place illusion and plausibility illusion. Place illusion refers to the sensation of physically being in an environment separate from the real world. Plausibility illusion refers to the sense that the surrounding environment and its events are taking place and happening. In interactions with digital characters, violations of plausibility illusion may cause breaks in presence. Such breaks can be studied through event-related brain potentials, such as the N400 component, which has been associated with expectancy and semantic violations.

By implementing a design to cause these breaks in presence, we may devise a new method to study presence in relation to digital characters. In particular, digital characters provide a unique context for plausibility and interactivity. Digital characters must act in accordance to the user’s expectations so as not to diminish the overall presence of the virtual environment. Meaning, digital characters must look, sound, and act in coherence to how the user expects them to.

This thesis proposes and implements an experimental apparatus designed to support future neuroscientific studies of digital character plausibility in a virtual reality environment. The apparatus enables interactions with both scripted and large language model driven digital characters and introduces controlled plausibility violations in form of character based glitches to elicit measurable responses and allow comparison between the block level conditions.

No participant study or data collection was conducted in this stage. Instead, this thesis focuses on developing a theoretical foundation and developing an experimental apparatus useful for studying digital character plausibility with neuroscientific signal analysis. Even though no participant data collection was done, the apparatus was still validated in a laboratory setting with experts to analyze and assess functionality and suitability for future EEG-based experiments