A neural link between affective understanding and interpersonal attraction

Abstract

Being able to comprehend another person's intentions and emotions is essential for successful social interaction. However, it is currently unknown whether the human brain possesses a neural mechanism that attracts people to others whose mental states they can easily understand. Here we show that the degree to which a person feels attracted to another person can change while they observe the other's affective behavior, and that these changes depend on the observer's confidence in having correctly understood the other's affective state. At the neural level, changes in interpersonal attraction were predicted by activity in the reward system of the observer's brain. Importantly, these effects were specific to individual observer-target pairs and could not be explained by a target's general attractiveness or expressivity. Furthermore, using multivoxel pattern analysis (MVPA), we found that neural activity in the reward system of the observer's brain varied as a function of how well the target's affective behavior matched the observer's neural representation of the underlying affective state: The greater the match, the larger the brain's intrinsic reward signal. Taken together, these findings provide evidence that reward-related neural activity during social encounters signals how well an individual's "neural vocabulary" is suited to infer another person's affective state, and that this intrinsic reward might be a source of changes in interpersonal attraction.

Keywords: affective communication; confidence; human social relations; intrinsic reward; multivoxel pattern analysis.

Fig. 1.

Experimental design. To measure changes in interpersonal attraction during emotion observation, the participants’ attraction toward each target was assessed before (Left) and after (Right) emotion observation. (Middle) A sample emotion observation trial is shown (time intervals and screen shots are taken from experiment II). A trial consisted of a facial observation period during which a short video clip of the target experiencing fear or sadness was shown, followed by a fixation cross, an emotion judgment period, and a confidence rating period. Responses were given with a button box and fed back to the observer (orange frame around the selected emotion and orange dot on the confidence scale).

Fig. S1.

Graphical summary of data analysis steps. (i) Experiment I and experiment II tested whether an observer’s subjective confidence that they correctly understood a target’s affective state predicted postobservation attraction scores (red arrow) if all variance that could be explained by preobservation attraction scores was removed from both variables (dashed blue arrows). (ii–v) Experiment II additionally examined the neural mechanisms that might mediate between subjective confidence and changes in interpersonal attraction. (ii) First, regions in the brain’s reward system were identified whose activity covaried with subjective confidence (whole-brain analysis; red arrow). (iii) Second, we tested whether these neural confidence signals predicted changes in interpersonal attraction (ROI analysis, red arrow) if all variance that could be explained by preobservation attraction was removed from both variables (dashed blue arrows). (iv) Third, brain regions were identified where NOE matching covaried with subjective confidence and/or neural confidence signals in the reward system (whole-brain analyses; red arrows). (v) Fourth, we tested whether NOE matching in the anterior insula predicted changes in interpersonal attraction (ROI analysis; red arrow) if all variance that could be explained by preobservation attraction was removed from both variables (dashed blue arrows). Red double lines indicate cross-validated effects. Red circles indicate ROIs. Please note that independency of all ROI analyses was ensured by cross-validation (please see Materials and Methods for details).

Fig. 2.

Interindividual variability in the observers’ approach behavior toward the targets before and after emotion observation. Data were first centered, separately for each target and pre- and postobservation runs (i.e., the mean number of button presses executed for each target in each run was set to 0), and then averaged across all targets, separately for pre- and postobservation runs.

Fig. 3.

Confidence-related neural activity in the brain’s reward system and individual changes in interpersonal attraction. (A) Brain regions where neural activity during the facial observation period covaried with self-reported confidence. (B) Scatter plot illustrating the correlation between neural activity in the right ventral striatum and self-reported confidence. (C) Scatter plot illustrating the partial correlation between confidence-related neural activity in the right ventral striatum and the observer's postobservation approach behavior (variance that can be explained by preobservation approach behavior is removed). (D) Scatter plot illustrating the partial correlation between confidence-related neural activity in the right ventral striatum and the observer's postobservation approach behavior (variance that can be explained by preobservation approach behavior and general target effects are removed). (E) Brain regions where neural activity during the emotion judgment period covaried with self-reported confidence. (F) Scatter plot illustrating the correlation between neural activity in the mOFC and self-reported confidence. (G) Scatter plot illustrating the partial correlation between confidence-related neural activity in the mOFC and the observer's postobservation approach behavior (variance that can be explained by preobservation approach behavior is removed). (H) Scatter plot illustrating the partial correlation between confidence-related neural activity in the mOFC and the observer's postobservation approach behavior (variance that can be explained by preobservation approach behavior and general target effects are removed). Note: SPMs (height threshold T[51] = 5.5, P = 0.05, FWE-corrected at voxel level in A; height threshold T[51] = 3.2, extent threshold k = 100 voxels, P = 0.001, FWE-corrected at cluster level in E) are superimposed onto a rendered surface and coronal/axial sections of a T1-weighted map of a standard brain (MNI space). For the scatter plots in B and F, trialwise data of each observer (i.e., 96 data points) were z-standardized and rank-ordered according to BOLD parameter estimates and then averaged across observers, separately for each rank. For the scatter plots in C, D, G, and H, targetwise data of each observer (i.e., 6 data points) were z-standardized and rank-ordered according to BOLD parameter estimates and then averaged across observers, separately for each rank. Error bars represent SEMs.

Fig. 4.

Neural observation–experience matching (NOE matching), self-reported confidence, and neural confidence signals in the mOFC. (A) Brain regions where NOE matching covaried with self-reported confidence (orange, cluster 1) and neural confidence signals in the mOFC (red, cluster 2), respectively. (B and C) Scatter plots illustrating the correlation between NOE matching in each cluster and self-reported confidence (orange)/neural confidence signals in the mOFC (red). Note: SPMs (height threshold T[51] = 3.2, extent threshold k = 10 voxels, P = 0.05, FWE-corrected at cluster level) are superimposed onto a rendered surface and coronal/axial sections of a T1-weighted map of a standard brain (MNI space). For the scatter plots in B and C, trialwise data of each observer (i.e., 96 data points) were z-standardized and rank-ordered according to NOE matching and then averaged across observers, separately for each rank. Error bars represent SEMs.