Disgust and the rubber hand illusion: A registered replication report of Jalal, Krishnakumar, and Ramachandran (2015)

Abstract

Heightened experience of disgust is a feature of obsessive-compulsive disorder (OCD), particularly in contamination-related OCD (C-OCD). Previous studies of the rubber hand illusion (RHI) reported that the sense of body ownership is related to the interaction between vision, touch, and proprioception. A recent study demonstrated a link between the RHI and disgust, reporting an interaction between these three perceptual modalities and disgust (Jalal, Krishnakumar, Ramachandran, 2015). However, there have been no direct replications of this initial study. We proposed a direct replication of Jalal et al.’s (2015) study. Based on a power analysis, we examined a minimum of 119 participants to determine whether placing contamination-related stimuli on a rubber hand causes OCD-like disgust among healthy participants while experiencing the RHI. In addition, we tested the cross-cultural validity of the previous findings, testing whether Japanese participants experience more intense disgust when a rubber hand and a participant’s hidden hand were stroked synchronously, compared with asynchronous stroking. This replication provides insight into potential applications of this study protocol in the treatment of OCD.

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“…Then, we calculated the effect size, f, as follows: f = √(η 2 /(1 -η 2 ) = 0.302. The small sample size may overestimate the effect size so, as a replication convention (e.g., Nitta et al, 2018), we halved the effect size of the original experiment, and used G*Power 3.1.9.3 (Faul et al, 2009) to conduct a power analysis (i.e., to 0.151). In G*Power, we set the significance level α = 0.05, power level 1-β = 0.95, and effect size f = 0.151.…”