Abstract: Presence has become an increasingly central component of Games User Research (GUR) as developments in technology continuously make modern video games more conducive to the sensation of ‘being there’ in virtual environments. The quality of games is now commonly evaluated based on how reliably they elicit presence; however, no standardized objective measure of presence currently exists. This study investigated two physiological measures, Galvanic Skin Response (GSR) and task-irrelevant Event-Related Potentials (ERPs), as potential objective indicators of presence in games. A total of 34 participants were divided into low or high presence groups based on their self-reported presence evoked from experiencing a horror game while task-irrelevant tones were being played. It was hypothesized that presence is associated with attentional resources being fully absorbed by the game, which would lead to less or insufficient perceptual resources available for processing the concurrent game-irrelevant oddball-task. This effect was expected to manifest as a measurable decrease in early ERP component amplitudes. It was also hypothesized that presence would make players react to emotion-eliciting events as if they were real, which would result in more GSR peaks throughout the game while not impacting event response magnitude. ERP components (N1, MMN and SW), GSR peaks/min and response magnitude were compared between the presence groups revealing significant differences in GSR peaks/min and early ERP components of N1 and MMN, but not in GSR response magnitude. The findings support the hypotheses and show that GSR peaks/min, N1 and MMN correlate with presence and have potential as presence indicators.