Page 70 - Like me, or else... - Michelle Achterberg

Chapter 3
Noise blast duration
A repeated measures ANOVA was performed on noise blast duration after positive, negative, and neutral feedback. Results showed a significant main effect of type of social feedback on noise blast duration, F(2, 58)=75.57, p<.001 (GG corrected), with a large effect size (ω2 = 0.41), see Figure 1d. Pairwise comparisons (Bonferroni corrected) revealed that noise blast duration after negative feedback (M=1517.08, SD=126.94) was significantly longer than noise blast duration after neutral feedback (M=930.41; SD=84.77, p<.001), and after positive feedback (M=483.62; SD=47.19, p<.001). Noise blast duration after neutral feedback was significantly longer than after positive feedback (p<.001).
To derive a measure indicative of individual differences in aggression we calculated the differences in noise blast duration between negative versus neutral feedback and positive versus neutral feedback. The noise blast difference for positive-neutral was significantly negatively correlated to the noise blast difference for negative-neutral (r= -.48, p=.008), indicating that shorter noise blasts after positive feedback (compared to neutral feedback) were related to longer noise blasts after negative feedback (compared to neutral feedback). Next, noise blast differences were correlated with the exit questions. The difference of negative-neutral was positively correlated to the feedback liking of positive feedback (r= .39, p=.032) and negatively correlated to the feedback liking of negative feedback (r= -.57, p=.001), indicating that longer noise blasts after negative feedback were related to a stronger preference for positive social feedback and a stronger disfavor of negative social feedback see Figures S1a and S1b. Similarly, the noise blast difference of positive-neutral was negatively correlated to the feedback liking of positive feedback (r= -.42, p=.021) and positively correlated to the feedback liking of negative feedback (r= .73, p<.001), indicating that a stronger preference for positive social feedback and a stronger disfavor of negative social feedback were related to shorter noise blasts after positive feedback (see Figures S1c and S1d).
fMRI whole brain analyses
Social evaluation
The first goal was to examine neural activity in the contrast positive versus negative feedback at the moment of peer feedback. The contrast Positive > Negative feedback resulted in activation with local maxima in the bilateral lateral occipital lobes, left postcentral, and activation in the right and left striatum, extending into subgenual ACC (see Figure 2a, Table S1). The contrast Negative > Positive feedback did not result in any significant clusters of activation. Next, we tested how neural activity to positive and negative social feedback related to a neutral baseline condition. The contrast Negative > Neutral feedback resulted in activity in the bilateral insula and mPFC, see Figure 2b (Table S2). The reversed contrast (Neutral > Negative feedback) did not result in any significant clusters
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