Research ArticleCOGNITIVE NEUROSCIENCE

Does inappropriate behavior hurt or stink? The interplay between neural representations of somatic experiences and moral decisions

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Science Advances  16 Oct 2020:
Vol. 6, no. 42, eaat4390
DOI: 10.1126/sciadv.aat4390
  • Fig. 1 Experimental design.

    Each trial began with a pictorial cue predicting either a pain or disgust stimulation. After a variable interstimulus interval (ISI), participants had to read a dilemma and judge a presented course of action on a continuous visual analog scale (VAS) of appropriateness (from extremely inappropriate to extremely appropriate). Next, participants were instructed to slowly breathe out during a countdown period. Then, a breathe in instruction appeared together with the stimulus delivery, which could be either olfactory or thermal. Consequently, participants rated the unpleasantness associated with the stimulus on a VAS (from extremely unpleasant to extremely pleasant), which was followed by an empty intertrial interval (ITI). Four different kinds of predictive cues were presented, indicating the unpleasantness (high/low) and modality (pain/disgust) of the upcoming stimulation (thermal pain/olfactory disgust). Please see Materials and Methods for details about duration and number of trials in each condition of experiments 1 and 2.

  • Fig. 2 Thermal and olfactory events: Subjective unpleasantness.

    Ratings for thermal (left) and olfactory (right) stimuli in reference trials, as well as trials following moral and nonmoral dilemmas, in experiment 1 (A) and in experiment 2 (B). Data from 25 subjects for experiment 1 and 27 subjects for experiment 2. Red boxplots refer to thermal stimulations, whereas blue boxplots refer to olfactory events. Darker colors refer to unpleasant conditions (HP and HD), whereas lighter tones refer to neutral controls (LP and LD). Each boxplot describes the median value (central mark), the interquartile range (boxes’ edges), and the extreme points of the distribution (whiskers) without considering outliers. Single-subject data points are also plotted over each boxplot as colored circles. “***” refers to P < 0.001 in a linear mixed model probing differential responses across conditions.

  • Fig. 3 Thermal and olfactory events: GSR.

    (A) Average GSR for thermal (left) and olfactory (right) stimuli in reference trials, as well as following moral and nonmoral dilemmas. Each boxplot describes the median value (central mark), the interquartile range (boxes’ edges), and the extreme points of the distribution (whiskers) without considering outliers. Single-subject data points are also plotted over each boxplot as colored circles. “***,” “**,” and “*,” refer to P < 0.001, P < 0.01, and P < 0.05, respectively, for a generalized linear mixed model test probing differential responses across conditions. (B) Multilevel regression describing the relationship between GSR to HP (left) and HD (right) and ratings of Emotional Engagement associated with each dilemma from an independent validation study (see Materials and Methods). Each plot shows a group-wise linear dependency (with a shaded area describing the 95% confidence interval), overlaid by individual regression dotted lines. The t scores of the multilevel regression are also displayed, with “*” referring to significance at P < 0.05. Please note that GSR is here displayed in log scale only for readability purposes, as they were analyzed in their raw values.

  • Fig. 4 Thermal and olfactory events: Neural responses.

    (A) Whole-brain maps displaying differential response to HP-LP (left) and HD-LD (right) in reference trials. (B) Signal associated with thermal (left) and olfactory (right) stimuli in reference trials, as well as trials following moral and nonmoral dilemmas. Individual responses were calculated by averaging the parameter estimates (βs) from the MCC (left) and vAI (right) in the analysis of reference trials. Each boxplot describes the median value (central mark), the interquartile range (boxes’ edges), and the extreme points of the distribution (whiskers) without considering outliers. Single-subject data points are also plotted over each boxplot as colored circles. “***,” “**,” and “*” refer to P < 0.001, P < 0.01, and P < 0.05, respectively, for a generalized linear mixed model test probing differential responses across conditions. (C) Multilevel regression describing the relationship between neural activity to HP (left) and HD (right) and ratings of appropriateness from an independent validation study (see Materials and Methods). Each plot shows a group-wise linear dependency (with a shaded area describing the 95% confidence interval), overlaid by individual regression dotted lines. The t scores of the multilevel regression are also displayed, with “*” referring to significance at P < 0.05. BOLD, blood-oxygen-level dependent signal.

  • Fig. 5 Neurological whole-brain signatures.

    (A) Whole-brain maps displaying regions contributing the most to the prediction of the unpleasantness associated with heat (left) and olfaction (right) using an independent dataset from Sharvit et al. (18). Red and orange blobs refer to regions contributing to the prediction of heat, whereas blue and cyan blobs refer to regions contributing to the prediction of olfaction. Color tones indicate the significance of the contribution as assessed through bootstrap resampling approaches (see Materials and Methods). (B) Unpleasantness for thermal (left) and olfactory stimuli (right) from the current study, as predicted by the corresponding signatures. Each boxplot describes the median value (central mark), the interquartile range (boxes’ edges), and the extreme points of the distribution (whiskers) without considering outliers. Single-subject data points are also plotted over each boxplot as colored circles. Thal, thalamus; Amy: amygdala. “***” and “**” refer to P < 0.001 and P < 0.01, respectively, for a generalized linear mixed model test probing differential responses across conditions.

  • Fig. 6 Dilemma events: Neural responses.

    (A) Whole-brain maps displaying differential response to moral-nonmoral dilemmas in both reading (brown blobs) and rating epochs (green blobs). (B) Whole-brain maps displaying regions implicated in the mediation analysis. The parameters extracted from the portion of the PCC showing conjoint activity for paths a (yellow blobs), b (purple blobs), and a × b (cyan blobs). “***” refers to parameters being significantly higher than 0 under bootstrap testing. STS, superior temporal sulcus.

Supplementary Materials

  • Supplementary Materials

    Does inappropriate behavior hurt or stink? The interplay between neural representations of somatic experiences and moral decisions

    G. Sharvit, E. Lin, P. Vuilleumier, C. Corradi-Dell’Acqua

    Download Supplement

    This PDF file includes:

    • Methods: Modelling whole-brain signatures
    • Results: Follow-up of Dilemma Events
    • Tables S1 to S3
    • Figs. S1 to S3

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