The Onset Time of the RHI was analysed with a similar 2 × 2 rmANOVA. Yet, given that not all participants reported an illusion in all four experimental conditions, statistical analyses were only run on the data from participants who responded in all the blocks (n = 12;
Finally, given that Subjective Reports were given on a continuous visual analog scale (from −100 = strongly disagree to +100 = strongly agree) instead of a 7-points Likert scale,22 (link) participants’ responses were also analysed through parametric tests. Participants’ agreement with each statement of the questionnaire were first averaged across question type (i.e., RHI/control items), and then analysed in a 2 (spatial-congruency: congruent, incongruent) x 2 (effector-type: hand, eye) x 2 (item-type: illusion, control) rmANOVA.
For each of the three dependent variables, we expected a main effect of spatial-congruency, in line with the general principle that crossmodal stimulation must be spatially congruent in order to elicit the RHI.37 (link) Crucially, in line with our main hypothesis of similar RHI for hand and eye movements, we also predicted no significant interaction between main effects. Given that the experiment was designed to allow asserting the null hypothesis (i.e., eye movements and hand movements induce the same amount of RHI), non-significant interactions between spatial-congruency and effector-type were further tested through Bayesian t-tests on the difference between spatially congruent/incongruent conditions in each type of movement. This allowed us to determine whether the datasupported the null hypothesis or if, alternatively, the null result could reflect insufficient statistical power.26 (link) All the ANOVAs were conducted using IBM SPSS Statistics for Windows, version 23 (IBM Corp.,USA). Bayesian analyses were run on JASP v. 0.12.1 (JASP Team 2016, University of Amsterdam).