Supplementary Material Figure S1. Illustrative example of the design matrix from one participant with the regressors of the first-level generalized linear model (GLM) represented as columns. 1 Supplementary Material Figure S2. Overview of all interaction or main effects as well as subcontrasts of the involved subconditions with the significant second-level linear mixed-effects models (LMM) HbO estimates projected onto a 3-D brain surface. 2 Figure S3. Overview of all interaction or main effects as well as subcontrasts of the involved subconditions with the significant second-level linear mixed-effects models (LMM) HbR estimates projected onto a 3-D brain surface. Frontiers 3 Supplementary Material Figure S4. Overview of the significant effects of the second-level linear mixed-effects models (LMM) for the HbO and HbR analyses when subtracting the task-induced workload from each condition (Silence High and Silence Low). The additional analyses serve to investigate the combination of both factors - emotion and workload in the interactions. Further, they allow to investigate the brain activation patterns associated with workload induced solely by the task (B; Silence High - Silence Low) and the auditory distractions (C; ((Negative High - Silence High) + (Neutral High - Silence High) + (Positive High - Silence High)) - ((Negative Low - Silence Low) + (Neutral Low - Silence Low) + (Positive Low - Silence Low))). 1 ADDITIONAL ANALYSES USING THE SILENCE CONDITION We included the silence condition to investigate the effects of the workload induced solely by the task, the workload induced by the distraction and the effect of emotion without task workload. The rationale was the following: • By subtracting the silence conditions, the workload induced by the task should be mitigated. In the presence of a true interaction between the emotion and workload, we should not observe any significant interactions between these factors when subtracting the respective silence condition from each condition (e.g., Neutral High - Silence High; Negative High - Silence High, Positive High - Silence High, Neutral Low - Silence Low; Negative Low - Silence Low, Positive Low - Silence Low). Our results revealed no significant interaction effects after subtracting the silence condition (gray information box). • Since subtracting the silence condition should primarily remove task-induced workload, the main emotion effects remain unaffected. The results of the main emotion contrasts should be comparable to those without subtracting the silence conditions. The results, where we subtracted the silence condition, demonstrated similar HbO main emotion effects compared to the original analyses (A). In the HbR analyses, we did not observe a significant main emotion effect when comparing neutral to positive 4 distractions, indicating that this particular contrast might have been partially influenced by task-induced effects (gray information box). Frontiers 5 Supplementary Material Figure S5. Interaction effects of the subjective ratings (arousal, valence, and effort) and performance measures (reaction time and accuracy). Dots and error bars illustrate the bootstrapped mean and its Bonferroni-corrected 95% confidence interval across participants per contrast. 6 Figure S6. Subcontrasts between subconditions of the subjective ratings (arousal, valence, and effort) and performance measures (reaction time and accuracy). Dots and error bars illustrate the bootstrapped mean and its Bonferroni-corrected 95% confidence interval across participants per contrast. Frontiers 7 Supplementary Material Table S1. Overview of the channels, optodes, Brodmann Area (BA) correspondences (exceeding a specificity of above 20 %), and MNI coordinates based on the fOLD toolbox. L: left; R: right. Channel Source Detector Brodmann Area X (mm) Y (mm) Z (mm) Specificity (%) 1 S12 (FC2) D3 (F2) R BA8 - Frontal eye fields 24 26 55 58 R BA9 - Dorsolateral prefrontal cortex 33 2 S12 (FC2) D12 (FCz) R BA6 - Pre-Motor and Supplementary Motor Cortex 14 13 66 63 R BA8 - Frontal eye fields 35 3 S3 (Fz) D3 (F2) R BA9 - Dorsolateral prefrontal cortex 10 41 50 69 R BA8 - Frontal eye fields 29 4 S5 (F4) D3 (F2) R BA9 - Dorsolateral prefrontal cortex 30 40 41 68 R BA46 - Dorsolateral prefrontal cortex 22 5 S5 (F4) D7 (FC4) R BA9 - Dorsolateral prefrontal cortex 44 25 40 31 R BA44 - pars opercularis, part of Broca’s area 27 6 S12 (FC2) D7 (FC4) R BA6 - Pre-Motor and Supplementary Motor Cortex 39 12 54 38 R BA9 - Dorsolateral prefrontal cortex 36 R BA8 - Frontal eye fields 21 7 S2 (AF4) D1 (AFz) R BA10 - Frontopolar area 13 61 24 72 8 S2 (AF4) D9 (Fp2) R BA10 - Frontopolar area 25 63 9 69 R BA11 - Orbitofrontal area 22 9 S6 (Fpz) D9 (Fp2) R BA10 - Frontopolar area 13 67 0 54 R BA11 - Orbitofrontal area 45 10 S8 (AF8) D9 (Fp2) R BA10 - Frontopolar area 34 59 -2 31 R BA11 - Orbitofrontal area 30 R BA46 - Dorsolateral prefrontal cortex 20 11 S10 (F8) D10 (F10) R BA38 - Temporopolar area 52 30 -13 36 12 S10 (F8) D14 (FT8) R BA38 - Temporopolar area 57 21 -4 32 13 S14 (FC6) D7 (FC4) R BA44 - pars opercularis, part of Broca’s area 56 12 33 41 R BA6 - Pre-Motor and Supplementary Motor Cortex 40 14 S5 (F4) D5 (F6) R BA45 - pars triangularis Broca’s area 46 38 24 71 R BA46 - Dorsolateral prefrontal cortex 23 15 S10 (F8) D5 (F6) R BA45 - pars triangularis Broca’s area 55 36 5 66 16 S14 (FC6) D5 (F6) R BA45 - pars triangularis Broca’s area 58 24 18 53 R BA44 - pars opercularis, part of Broca’s area 29 17 S14 (FC6) D14 (FT8) R BA48 - Retrosubicular area 61 11 8 28 R BA6 - Pre-Motor and Supplementary Motor Cortex 26 18 S8 (AF8) D5 (F6) R BA45 - pars triangularis Broca’s area 48 46 5 44 R BA46 - Dorsolateral prefrontal cortex 43 19 S2 (AF4) D5 (F6) R BA46 - Dorsolateral prefrontal cortex 40 50 16 47 R BA45 - pars triangularis Broca’s area 31 20 S3 (Fz) D12 (FCz) BA8 middle - Frontal eye fields 1 27 58 60 BA6 middle - Pre-Motor and Supplementary Motor Cortex 24 21 S3 (Fz) D1 (AFz) BA9 middle - Dorsolateral prefrontal cortex 2 50 39 62 BA10 middle - Frontopolar area 20 22 S6 (Fpz) D1 (AFz) BA10 middle - Frontopolar area 1 64 14 87 23 S11 (FC1) D2 (F1) L BA8 - Frontal eye fields -23 26 56 64 L BA9 - Dorsolateral prefrontal cortex 26 24 S3 (Fz) D2 (F1) L BA9 - Dorsolateral prefrontal cortex -9 41 50 63 L BA8 - Frontal eye fields 35 25 S4 (F3) D2 (F1) L BA9 - Dorsolateral prefrontal cortex -31 39 41 67 L BA46 - Dorsolateral prefrontal cortex 25 26 S4 (F3) D6 (FC3) L BA9 - Dorsolateral prefrontal cortex -45 25 41 37 L BA44 - pars opercularis, part of Broca’s area 27 27 S11 (FC1) D6 (FC3) L BA6 - Pre-Motor and Supplementary Motor Cortex -38 12 55 38 L BA9 - Dorsolateral prefrontal cortex 35 L BA8 - Frontal eye fields 23 28 S11 (FC1) D12 (FCz) L BA6 - Pre-Motor and Supplementary Motor Cortex -13 12 67 73 L BA8 - Frontal eye fields 26 29 S1 (AF3) D1 (AFz) L BA10 - Frontopolar area -12 62 23 76 30 S1 (AF3) D8 (Fp1) L BA10 - Frontopolar area -24 63 9 70 L BA11 - Orbitofrontal area 20 31 S6 (Fpz) D8 (Fp1) L BA10 - Frontopolar area -12 67 0 54 L BA11 - Orbitofrontal area 45 32 S7 (AF7) D8 (Fp1) L BA11 - Orbitofrontal area -33 59 -2 33 L BA46 - Dorsolateral prefrontal cortex 25 L BA10 - Frontopolar area 25 33 S9 (F7) D11 (F9) L BA38 - Temporopolar area -49 31 -12 32 L BA47 - Inferior prefrontal gyrus 32 34 S9 (F7) D13 (FT7) L BA38 - Temporopolar area -54 21 -4 32 L BA45 - pars triangularis Broca’s area 24 35 S13 (FC5) D6 (FC3) L BA44 - pars opercularis, part of Broca’s area -55 12 34 48 L BA6 - Pre-Motor and Supplementary Motor Cortex 36 36 S13 (FC5) D4 (F5) L BA45 - pars triangularis Broca’s area -56 24 20 53 L BA44 - pars opercularis, part of Broca’s area 34 37 S13 (FC5) D13 (FT7) L BA48 - Retrosubicular area -59 11 9 32 L BA6 - Pre-Motor and Supplementary Motor Cortex 24 38 S9 (F7) D4 (F5) L BA45 - pars triangularis Broca’s area -53 37 6 80 39 S4 (F3) D4 (F5) L BA45 - pars triangularis Broca’s area -46 39 26 73 L BA46 - Dorsolateral prefrontal cortex 22 40 S7 (AF7) D4 (F5) L BA45 - pars triangularis Broca’s area -47 46 6 49 L BA46 - Dorsolateral prefrontal cortex 43 41 S1 (AF3) D4 (F5) L BA46 - Dorsolateral prefrontal cortex -39 50 17 49 L BA45 - pars triangularis Broca’s area 32 8 Table S2. Summary of the fixed effect factor Handedness when included in the second-level linear mixed-effects models (LMM). Contrast Estimate Std. Error df t p 95% CI HBO Interaction Negative - Positive High - Low -0.308 0.129 16 -2.383 0.03 [-0.713, 0.1] Neutral - Negative High - Low 0.481 0.178 16 2.705 0.016 [-0.04, 1.044] Neutral - Positive High - Low 0.292 0.169 16 1.722 0.104 [-0.259, 0.898] Main Emotion Negative - Positive 0.0 0.164 16 0.0 1.0 [-0.488, 0.55] Neutral - Negative 0.008 0.132 16 0.058 0.954 [-0.435, 0.441] Neutral - Positive 0.007 0.105 16 0.068 0.947 [-0.355, 0.336] Main Workload High - Low -0.253 0.138 16 -1.841 0.084 [-0.689, 0.199] HBR Interaction Negative - Positive High - Low 0.116 0.099 16 1.171 0.242 [-0.218, 0.408] Neutral - Negative High - Low -0.276 0.11 16 -2.505 0.023 [-0.632, 0.091] Neutral - Positive High - Low -0.186 0.099 16 -1.879 0.061 [-0.544, 0.14] Main Emotion Negative - Positive -0.086 0.11 16 -0.779 0.447 [-0.45, 0.294] Neutral - Negative 0.078 0.123 16 0.639 0.532 [-0.334, 0.505] Neutral - Positive -0.008 0.098 16 -0.078 0.938 [-0.333, 0.306] Main Workload High - Low 0.003 0.159 16 0.02 0.984 [-0.512, 0.503] Table S3. Summary of the second-level linear mixed-effects model (LMM) for the HbR Interaction Effect Contrast Negative - Positive Emotion High - Low Load in the significant channel S9-D11. Estimate Std. Error df t p 95% CI Workload 0.476 0.189 51 2.515 0.015* [0.102, 0.843] Emotion 0.479 0.189 51 2.536 0.014* [0.105, 0.862] Workload * Emotion -0.645 0.267 51 -2.414 0.019* [-1.179, -0.107] Frontiers 9 Additional Analyses using the Silence Condition