Page 69 - Like me, or else... - Michelle Achterberg

The neural basis of aggression regulation
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Higher-level group analyses
Subject-specific contrast images were used for the group analyses. A full factorial ANOVA with three levels (positive, negative, and neutral feedback) was used to investigate the neural response to the social feedback event. We calculated the contrasts ‘Positive versus Negative feedback’, ‘Positive versus Neutral feedback’ and ‘Negative versus Neutral feedback’. To investigate regions that were activated both after negative social feedback and after positive social feedback, we conducted a conjunction analysis to explore the main effect of social evaluation. Based on Nichols et al. (2005), we used the ‘logical AND’ strategy. The ‘logical AND’ strategy requires that all the comparisons in the conjunction are individually significant (Nichols et al., 2005).
All results were False Discovery Rate (FDR) cluster corrected (pFDR<.05), with a primary voxel-wise threshold of p<.005 (uncorrected) (Woo et al., 2014). Coordinates for local maxima are reported in MNI space. To further visualize patterns of activation in the clusters identified in the whole brain regression analysis, we used the MarsBaR toolbox (Brett et al., 2002) (http://marsbar.sourceforge.net).
In all behavioral repeated measures analyses, Greenhouse-Geisser (GG) corrections were applied when the assumption of sphericitiy was violated. When outliers were detected (Z-value <-3.29 or >3.29), scores were winsorized (Tabachnick and Fidell, 2013).
Results
The ratings of how much participants liked the maximum intensity noise blast indicated that overall the noise blast was not liked (M=1.47, SD=0.78; range 1-4) and much disliked (M=5.67, SD=1.30; range 1-7). These results show that the noise blast was indeed perceived as a negative event by the participants.
Social feedback manipulation check
To verify whether participants differentially liked the social feedback conditions (positive, negative, neutral), , we analyzed the exit questions with a repeated measures ANOVA. Analyses showed a significant main effect of type of feedback on feedback liking, F(2, 58)=53.63, p<.001 (GG corrected), with a large effect size (ω2 = 0.53). Pairwise comparisons (Bonferroni corrected) showed that participants liked negative feedback (M=3.13, SD=0.14) significantly less than neutral feedback (M=4.23, SD=0.14, p<.001) and positive feedback (M=5.23, SD=0.16, p<.001). Participants also liked neutral feedback significantly less than that positive feedback (p<.001).
Behavioral analyses
Noise blast manipulation check
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