Quantifying human subjective experience and social interaction using the eXperience Induction Machine.

With the advance of novel brain imaging technology more correlations between complex human properties and the neuronal substrate can be assessed. However, thus far, not many well-validated paradigms exist that would allow for a systematic and quantitative exploration of these phenomena. For instance, despite the rapid technological advances in the domain of mixed and virtual reality systems, a fundamental issue remains how we can define and quantify "presence". A standard approach has been to use questionnaires and self-report measures. However, it has been well established that humans' capabilities to access and externalize their internal states are limited. Hence, we have investigated the question whether other less subjective measures can be devised that can corroborate subjective self-reports on presence. In particular, we have developed a quantitative recollection task that assesses the ability of human subjects (N=40) to recollect the factual structure and organization of a structured and fully controlled experience in a human accessible mixed reality space, the eXperience Induction Machine (XIM). In this structured experience - referred to as the "Autodemo"--a virtual guide explains the key elements and properties of XIM while the user is able to freely move around in the space. To evaluate the users' experience and the amount of factual information retained about the Autodemo, we used the ITC-SOPI questionnaire and a recall test specifically designed for the Autodemo. We found significant correlations between spatial presence and engagement factors of ITC-SOPI and recall performance. Moreover we observed an interaction with the participants' gender. Our results show that we can assess correlates of "presence" by focusing on other dependent measures such as those related to memory and performance. Additionally, our work exemplifies how virtual and mixed reality systems provide new ways to address fundamental questions in psychology and cognitive neuroscience.