Abstract
This paper aims to differentiate between the sense of presence in virtual environments (VE) from that in oneiric virtual environment (OVE) and to sketch the necessary and sufficient conditions of triggering an oneiric consciousness. Criteria determining the singularity of the sense of presence in OVE results from a description of the dream state that has been taken as an apparatus and from a correlation between this description and specific scientific experiments in cybernetics and neuroaesthetics fields. Based on these substantial theoretical approaches, it has been argued that the key elements to distinguish experiences in VE from those in OVE are indeterminacy and passive body posture. Findings have also revealed that modalities determining an oneiric state have been distinguished through a comparison between dreaming, hallucinating and imagining.