Figure 6. Correlations between behavioral percepts of the illusion and neural hand-centered remapping. A, Individual proprioceptive drift and group average. The bars represent the difference between post- and pre-measurements (negative values more to the left, positive values more to the right), in the synchronous and the asynchronous condition (average of 3 trials; error bars represent SEM). The drift was significantly larger in the synchronous than in the asynchronous condition (drift in the synchronous condition: −4.75 ± 2.6 cm, 2-tailed t test against 0, t = 4.53, p = 0.001; drift in the asynchronous condition: 0.5 ± 1.78, 2-tailed t test against 0, t = 0.12, p = 0.45). B, Participants were asked to rate four statements on a scale from −3 (“completely disagree”) to +3 (“agree completely”) after 1 min of synchronous or asynchronous stimulation. They reported stronger illusory referral of touch to the rubber hand after the synchronous condition compared with the asynchronous one (Q1, Wilcoxon's signed-rank test, n = 13, Z = 3.18, p = 0.002). They also experienced a significantly stronger sense of ownership over the prosthetic hand after the synchronous than the asynchronous condition (Q2, Wilcoxon's signed-rank test, n = 13, Z = 2.80, p = 0.005). C, A whole-brain second-level regression model revealed a significant linear relationship (p < 0.05 corrected) between the proprioceptive drift toward the rubber hand and the effect size of the BOLD-adaptation response indexing hand-centered remapping to the rubber hand across individuals (contrast described in Fig. 7 and Materials and Methods). D, Significant linear regression (p < 0.05 corrected) between the subjectively rated strength of ownership (questionnaire data) and the BOLD-adaptation response indexing hand-centered remapping to the rubber hand across individuals. FWE, Familywise error.