Virtual Placebo: a scoping review of control conditions in randomized controlled trials of psychological immersive virtual reality interventions

Abstract

Research on immersive virtual reality (IVR) as a therapeutic tool is growing rapidly, with randomized controlled trials (RCTs) now commonplace. Yet the control conditions in many of these studies that claim strong specific IVR effects vary from usual care to active immersive experiences, making it difficult to draw clinically meaningful conclusions. We conducted a scoping review of recent literature on psychological IVR interventions to assess the main forms of control conditions used and their relations to study outcomes. In this paper, we make the case that most of the recent RCTs studying the effects of specific IVR interventions compare active immersive VR to usual care with no multimedia component. This can lead to strong yet potentially misleading study outcomes and can potentially inflate the IVR interventions' effect. Namely, the lack of an appropriate immersive control condition may risk misattributing general effects of VR devices to the specific content of the intervention. In this review, we discuss the implications of these design choices and propose strategies for including a suitable "virtual placebo" condition to improve the methodological rigor and interpretability of results.