RESUMEN
BACKGROUND AND OBJECTIVE: Many recent studies in virtual reality (VR) have managed the sense of Presence to assess the suitability of their designs, mainly when focused on learning goals that require high user engagement, such as in serious games for psychomotor training. However, the place and plausibility illusions needed to promote Presence are achieved by combining different VR-based design cues, and their individual contribution to preserving the Presence's engagement/involvement component is still unclear. This article explored the single effect of breaking the sense of Presence per VR factor, i.e., removing VR cues related to Social Presence (human interactions), Self-Presence (embodiment), and Physical Presence (Scenario realism). METHODS: Thirty-three participants were asked to play an immersive VR simulation of an arcade game three times by experiencing a stepped Break of Illusion in one of the VR factors, i.e., while two factors were kept high, the remaining one was reduced to a low and null (hypothetical) level. The game difficulty was fixed after assessing each person's skills. RESULTS: Results showed that psychophysiology indicators (heart rate and skin conductance) were not affected by the level of illusion, whereas exercise intensity was significantly higher with low body and social presence-based conditions. Moreover, skin conductance was lower in the Social-presence group, which suggests that perspiration is only affected by breaks in realism (scenario and body representations). Based on the obtained evidence, we proposed some guidelines for adapting the design of immersive virtual environments through Breaks in Presence, mainly by changing the realism of the scenario and body representation depending on the skin conductance or the interaction with virtual humans depending on exercise intensity.