Dissociable early attentional control mechanisms underlying cognitive and affective conflicts

Abstract

It has been well documented that cognitive conflict is sensitive to the relative proportion of congruent and incongruent trials. However, few studies have examined whether affective conflict processing is modulated as a function of proportion congruency (PC). To address this question we recorded event-related potentials (ERP) while subjects performed both cognitive and affective face-word Stroop tasks. By varying the proportion of congruent and incongruent trials in each block, we examined the extent to which PC impacts both cognitive and affective conflict control at different temporal stages. Results showed that in the cognitive task an anteriorly localized early N2 component occurred predominantly in the low proportion congruency context, whereas in the affective task it was found to occur in the high proportion congruency one. The N2 effects across the two tasks were localized to the dorsolateral prefrontal cortex, where responses were increased in the cognitive task but decreased in the affective one. Furthermore, high proportions of congruent items produced both larger amplitude of a posteriorly localized sustained potential component and a larger behavioral Stroop effect in cognitive and affective tasks. Our findings suggest that cognitive and affective conflicts engage early dissociable attentional control mechanisms and a later common conflict response system.

Figure 1. Experimental protocol and behavioral results.

(A) The experimental design regarding Task types (cognitive task, affective task) and Stimulus congruence (congruence, incongruence). (B) Left panels: the high proportion congruency (HPC) block including 70% congruent trials and 30% incongruent trials; Right panels: the low proportion congruency (LPC) block including 30% congruent trials and 70% incongruent trials. (C,D) Left panels: mean RTs and mean error rates for congruent (yellow) and incongruent (green) trials in the HPC and the LPC contexts during affective task. Right panels: mean RTs and mean error rates for congruent (yellow) and incongruent (green) trials in the HPC and the LPC contexts during the cognitive task. The error bars represents one standard error.

Figure 2. Grand average ERP waveforms at Fz and POz for congruent (black solid lines) and incongruent (red dot lines) trials in the high proportion congruency (HPC) (Left panels) and the low proportion congruency (LPC) (Right panels) contexts during the cognitive task (two top panels) and affective task (two bottom panels).

Arrow = N1, Solid triangle = N2, open triangle = SP. *P < 0.05; **P < 0.01.

Figure 3. Dissociated effects of congruency context on N2 and SP during cognitive and affective tasks.

(A) Difference waves at Fz and POz between incongruent and congruent stimuli in the high proportion congruency (HPC) (blue solid lines) and the low proportion congruency (LPC) (red dot lines) context during the cognitive (top panels) and affective tasks (bottom panels). Solid triangle for N2, open triangle for SP. (B) Histogram shows the effect of stimulus congruency (i.e., incongruency vs. congruency) on N2 amplitude (μV) (Left panels) and SP amplitude (μV) (Right panels) in the HPC (blue columns) and the LPC (red columns) contexts during the cognitive (top panels) and affective (bottom panels) tasks.

Figure 4. The sLORETA source localization for the difference waves (incongruency minus congruency) of the N2 component between the low and high proportion congruency contexts during cognitive task (top panels) and affective tasks (bottom panels).

The image of N2 corresponds to 220 – 280 ms post-stimulus latency. A = anterior. P = posterior. S = superior. I = inferior. LH = left hemisphere. RH = right hemisphere. BH = both hemispheres. LV= left view. RV = right view. BV = bottom view. Red: the maximum activation, Blue: the minimum activation. Square: cognitive task, Circle: affective task.