The rubber hand illusion in children: What are we measuring?

The rubber hand illusion (RHI) is a much-studied bodily illusion that has been used in a wide number of populations to investigate the plasticity of the mental body representation. In adult participants, the wide adoption of the illusion has led to a proliferation of experimental variations of the illusion, and with that, considerable apparent inconsistencies in both empirical results and conceptual interpretations. In turn, this makes it challenging to integrate empirical findings and to identify what those findings together can tell us about the representation of the body in the brain. More recently, scientists have started applying the illusion to populations of children, in order to better understand how body representations develop in both typically developing children and in clinical populations. With this field now starting to expand, we believe it is both urgent and important to prevent unintended methodological variability from hindering the consistency of the paediatric literature as it has the adult literature. With this aim in mind, we review the 12 currently available paediatric RHI studies, and summarise their key methodological choices and conceptual definitions. We highlight a number of important discrepancies, particularly where seemingly equivalent analysis choices might significantly affect the interpretation of results, and make recommendations for future studies. We hope this will allow this important and emerging field to benefit from the synergy that results from multiple studies using convergent and consistent empirical methods.