3.2.1 N1 (120-220 ms)
The analyses on the N1 component detected a significant three-way interaction for type × flanker × context, F (2, 36778) = 4.31,p = .014 (see Figure 2). Follow-up tests revealed a significant interactive effect for flanker × type in the natural switching context (t = 5.84, p = .016), such that switch-incongruent trials (M = -2.03 ± 15.04 μV) elicited a smaller N1 effect compared to repeat-incongruent trials (M = -2.80 ± 15.92 μV). However, no such interactive effect was found in either the forced or voluntary switching contexts. Additionally, in the forced switching context, switch-incongruent trials (M = -3.11 ± 14.77 μV) elicited a stronger N1 effect compared to switch-congruent trials (M = -2.35 ± 13.29 μV), indicating that the typical flanker effect was only found in forced switching (Estimate = .74, SE =.37, t = 2.00, p = .045). Moreover, switch-incongruent trials in the natural switching context (M = -2.03 ± 15.04 μV) showed a smaller N1 effect compared to both the forced switching context (M = -3.12 ± 14.77 μV; Estimate = 1.13, SE = .32, t = -3.51, p = .001) and voluntary switching context (M = -2.46 ± 11.16 μV; Estimate = .84, SE = .33, t = 2.55, p = .016). No such differences were found between the forced and voluntary switching contexts (Estimate = -.29, SE = .33, t = -.87, p = .383).
Figure 2. Grand average waveforms time-locked to stimulus onset in the three switching contexts across central-parietal (A) and parietal (B) electrodes.