What Do Participants Expect to Experience in the Rubber Hand Illusion? A Conceptual Replication of Lush (2020)

Abstract

The sense of body ownership (the feeling that the body belongs to the self) is commonly believed to arise through multisensory integration. This is famously shown in the rubber hand illusion (RHI), where touches applied synchronously to a fake hand and to the participant’s real hand (which is hidden from view) can induce a sensation of ownership over the fake one. Asynchronous touches weaken or abolish the illusion, and are typically used as a control condition. Subjective experience during the illusion is measured using a questionnaire, with some statements designed to capture illusory sensation and others designed as controls. However, recent work by Lush (2020, Collabra: Psychology) claimed that participants may have different expectations for questionnaire items in the synchronous condition compared to the asynchronous condition, and for the illusion-related items compared to the control items. This may mean that the classic RHI questionnaire is poorly controlled for demand characteristics. In the current work a conceptual replication of Lush (2020) was performed. Participants were presented with a video of the RHI procedure and reported the sensations they would expect to experience, both in free response and by rating questionnaire items. Participants had greater expectations for illusion statements in the synchronous condition compared to the asynchronous condition, and for illusion statements compared to control statements. However, free responses suggested that such expectations may be at least partially driven by exposure to the questionnaire items. Further work is necessary to understand whether similar expectations exist for the true RHI procedure, what might drive them, and whether they have an impact on reported RHI experience.