Raincloud plots (Allen et al., 2021) of behavioral Data. The plot consists of a probability density plot, a line graph, and raw data points. ** p < 0.01, *** p < 0.001.

The P1 results in the single task and the dual task. (A) The event-related potential (ERP) waveforms for P1 component. The shaded rectangle represents the defined time windows and the shading above and below the ERP waveform represents the 95% confidence intervals. (B) Topographic distributions of average amplitude for each condition within the time window (110-150 ms) and the amplitude differences between congruent and incongruent trials in single and dual tasks. (C) Raincloud plots of amplitude for P1 across conditions. n.s., not significant.

The N450 and SP results in the single task and the dual task. (A) The event-related potential (ERP) waveforms for P1 and SP components. The shaded rectangle represents the defined time windows and the shading above and below the ERP waveform represents the 95% confidence intervals. (B) Topographic distributions of average amplitude for each condition within the time window (350-500 ms) and the amplitude differences between congruent and incongruent trials in single and dual tasks. (C) Raincloud plots of amplitude for N450 across conditions. (D) Topographic distributions of average amplitude for each condition within the time window (650-950 ms) and the amplitude differences between congruent and incongruent trials in single and dual tasks. (E) Raincloud plots of amplitude for SP across conditions. n.s., not significant, * p < 0.05, ** p < 0.01.

MVPA results for (A) the theta band, (B) the alpha band, and (C) the beta band. Dots denote significant differences from chance (P < 0.01). Shading represents clusters of significant time points (cluster-corrected).

Time-frequency results for the theta band. (A) Grand-average time-frequency representations for the theta band over fronto-central area (Fz, FCz, Cz) for each condition, and the difference activity between congruent and incongruent trials in single and dual tasks. (B) Topographic distributions of average amplitude for each condition within the defined time-frequency region of interest (4-7 Hz, 740-820 ms) and the magnitude differences between congruent and incongruent trials in single and dual tasks. (C) Raincloud plots of ERSP magnitudes for theta band across conditions. n.s., not significant. ** p < 0.01, *** p < 0.001.

Time-frequency results for the beta band. (A) Grand-average time-frequency representations for the beta band over the central area (C3, CP3, Cz, CP4, C4) for each condition, and the difference activity between congruent and incongruent trials in single and dual tasks. (B) Topographic distributions of average amplitude for each condition within the defined time-frequency region of interest (14-25 Hz, 920-1040 ms) and the magnitude differences between congruent and incongruent trials in single and dual tasks. (C) Raincloud plots of ERSP magnitudes for the beta band across conditions. n.s., not significant. *** p < 0.001.

Representational dissimilarity matrices for the interaction pattern in RT, SP, theta and beta. Each RDM is calculated as the Euclidean distances of data reflecting interaction pattern from 32 subjects.

Schematic illustration of experimental trial structures and stimuli types. (A) Dual-task structure, (B) Single-task structure, (C) Representative stimuli for congruent and incongruent conditions.