3.2.2 P3 (350-450 ms)
The analyses on the P3 component detected a significant main effect of
context, F (2, 38361) = 8.03, p < .001, and a
significant interaction for flanker × context, F (2, 38363) =
6.05, p = .002. Follow-up tests showed that the forced switching
context (M = 5.54 ± 17.53 μV) elicited a smaller P3 effect
compared to both natural switching (M = 6.28 ± 14.47 μV; Estimate
= -.76, SE = .19, t = -3.99, p < .001) and
voluntary switching (M = 5.99 ± 14.51 μV; Estimate = -.44, SE =
.19, t = -2.28, p = .034). Differences between the natural
and voluntary switching contexts did not reach significance (Estimate =
.33, SE = .19, t = 1.71, p = .088).
Planned pairwise comparisons within each context revealed a reversed
flanker effect in the forced switching context (Estimate = 1.61, SE =
.42, t = 3.81, p < .001), such that there was a
stronger P3 effect on congruent trials (M = 6.37 ± 17.60 μV)
compared to incongruent trials (M = 4.71 ± 17.42 μV). However,
this effect was not significant in the natural and voluntary switching
contexts (t s < 1.48, p s > .14).
Moreover, in incongruent trials, the forced switching context (M = 4.71 ± 17.42 μV) elicited smaller P3 amplitude compared to both
natural switching (M = 5.96 ± 14.61 μV; Estimate = -1.26, SE =
.27, t = -4.66, p < .001) and voluntary
switching (M = 5.79 ± 14.45 μV; Estimate = -1.07, SE = .27,t = -3.95, p < .001). Differences between the
natural and voluntary switching contexts were not significant (Estimate
= .19, SE = .27, t = .70, p = .483).
To recap, we observed a smaller N1 effect in the switch-incongruent
condition of the natural switching context compared to the other two
switching contexts. Differences between voluntary and forced switching
contexts were not significant. Importantly, the P3 amplitude of
incongruent trials in the forced switching context was smaller than both
natural and voluntary switching contexts. In addition, an atypical
flanker effect was detected on the P3 effect in the forced switching
context, whereas such effect was not found in the other two switching
contexts. These findings indicate that context-dependent language
control modulates executive control.