Group and individual differences in the non-predictive rTMS effects for SPOC on the variability of initial movement direction (VIMD). (a) Standard boxplot showing the effect broken down for two subsets of our sample, defined based on the moment of initiation (Tini). The inset depicts the differences between the Non-Predictive (NP) conditions and the NoTMS (NT) and Cz conditions for both groups. Individual data is depicted using unique symbol/colour/jitter combinations. Means are indicated by filled diamonds; outliers are red crosses. *t(11) = 4.22; p = 0.00072; d′ = 0.86, α = 0.003125; #t(11) = 5.04; p = 0.00019; d′ = 1.03, α = 0.00156. Indeed, the Non-predictive contrast appeared to be larger for the early than for the late initiators: t(22) = 3.39; p = 0.0027; d′ = 1.38 (two-tailed independent-samples t-test). No significant differences were found for late initiators: NP-NT: t(11) = 0.37; p = 0.36; d′ = 0.076; NP-Cz: t(11) = 0.65; p = 0.26; d′ = 0.13. Validity of these one-tailed paired-samples t-tests (p-values) was confirmed using 1,000,000 bootstraps. (b) Individual Non-predictive rTMS effects (i.e., NP-(NT-Cz)/2) for SPOC on VIMD, as a function of the average Tini in the Non-predictive conditions. With the exception of a single participant (open diamond), the rTMS effect was shown by participants initiating within 0.4 s of target appearance. (c) Individual Non-predictive rTMS effects for SPOC on VIMD as a function of individual Predictive rTMS effects (i.e., P-(NT-Cz)/2) for SPOC on VIMD. The red dashed unity line indicates equal Predictive and Non-predictive effects. For most early initiators the rTMS effect predominantly occurred in the Non-predictive conditions; only two participants also showed considerable Predictive effects.