When conducting audiovisual Stroop-like tasks, cognitive control is modality-specific and associated with significant congruency effects. This is according to research results published in Brain and Cognition.
To better understand modality-specific mechanisms associated with cognitive control, researchers utilized a Stroop-like task — integrating visual and auditory stimuli — in an event-related potential (ERP) study. The study included 24 participants (13 females; mean age 24.3 years).
Investigators displayed random visual and auditory stimuli to participants over the course of 10 blocks of trials lasting roughly 63 minutes. Electroencephalography (EEG) data were collected using a standard EEG cap, and ERP amplitudes were collected and analyzed. Investigators primarily focused on the congruency effect and the 3-way interaction of distractor modality switch x previous congruency x current congruency.
Results demonstrated significant main effects on current congruency (congruency effect); slower reaction times were noted for incongruent trials (mean, 485 ms; standard error of the mean [SEM], 13 ms) compared with congruent trials (mean, 470 ms; SEM, 12 ms). The 3-way interaction for distractor modality switch x previous congruency x current congruency was significant (F[1,23]=10.84; P =.003). Simple effect analyses indicated a significant interaction between previous congruency x current congruency (conflict adoption [CA] effect) in a modality-repetition condition, but not in a modality alteration condition (F[1,23]=7.84 and 2.39, respectively).
Error rate results were similar to those found with reaction times. The main current congruency effect was significant (F[1,23]=19.46; P <.01) and higher error rates were found with incongruent trials (mean, 3.8%; SEM, 0.8%).
Investigators found no significant congruency or CA effects on N2 amplitudes. P3 amplitudes were associated with a significant main effect of current congruency, with P3 less positive in incongruent trials compared with congruent trials.
Repeat measured analysis of variances for averaged event-related spectral perturbations within a time window of 250 ms to 500 ms indicated no significant main effects or 3-way interactions of distractor modality switch, previous congruency, or current congruency. Within the parietal area, these measures demonstrated a significant main effect for current congruency in the beta 1 band, likely due to stronger phasic activities in incongruent trials. Additional significant effect analyses found significant interactions between previous and current congruency for theta band power, alpha band power, and beta 1 band power.
Overall, significant CA effects on P3 amplitude and spectral power in the modality-repetition condition were found, indicating that the mechanism of cognitive control may be modality specific during Stroop-like conflict processing.
Study limitations include overlap in some stimulus features for some trials, the potential for confounding factors, and potential modality-specific asymmetries in congruency effects caused by domination of auditory processing by visual processing.
“The current study contributes to elucidating the mechanisms of cognitive control in a Stroop-like task by revealing modality-specific neural indices, including the CA effect on P3 amplitudes and spectral power, as well as the correlation between [reaction times] and P3 amplitudes,” the research shows.
Li Z, Yang G, Wu H, et al. Modality-specific neural mechanisms of cognitive control in a Stroop-like task. Brain Cogn. Published online December 21, 2020. doi:10.1016/j.bandc.2020.105662