Page 13 - Like me, or else... - Michelle Achterberg

General introduction
aspects of information processing. Social acceptance and rejection have been studied in a variety of experimental settings, for example by manipulating Instagram likes (Sherman et al., 2018b), by mimicking chat room conversations (Silk et al., 2012) or by simulating peer feedback on the participant’s profile (Somerville et al., 2006; Gunther Moor et al., 2010b; Dalgleish et al., 2017; Rodman et al., 2017). These studies showed that social rejection can be quite literally heartbreaking, as negative social feedback can result in cardiac slowing (Gunther Moor et al., 2010a), which was most pronounced in young adolescents compared to adults (Gunther Moor et al., 2014). Other studies found that social rejection resulted in increased pupil dilation (Silk et al., 2012). The pupil becomes more dilated in response to stimuli with a greater emotional intensity (Siegle et al., 2003), and is suggested to reflect increased activity in cognitive and affective processing regions of the brain.
Indeed, a wealth of neuroimaging research has shown that the significance of social evaluation is deeply rooted in our brain. Social acceptance, for example, has been associated with increased activity in striatal regions (Guyer et al., 2009; Davey et al., 2010; Gunther Moor et al., 2010b; Sherman et al., 2018b), specifically in the ventral striatum (VS, Figure 1). Numerous studies have shown that the VS is associated with reward processing (Sescousse et al., 2013) and this heightened activation could reflect the rewarding value of positive feedback. Social rejection, in contrast, has been related to increased activation in midline regions of the brain, such as the dorsal and subgenual anterior cingulate cortex (ACC) and medial prefrontal cortex (MPFC) (Cacioppo et al., 2013; Apps et al., 2016), see Figure 1. The dorsal ACC, together with the anterior insula (AI, Figure 1), have been suggested to signal social pain, as activity in these regions largely overlapped with brain activity after physical pain (Eisenberger and Lieberman, 2004; Kross et al., 2011; Rotge et al., 2015). However, other studies found the dorsal ACC and AI to be sensitive to expectancy violation (Somerville et al., 2006; Cheng et al., 2019) and have suggested that these regions might be important for evaluating social feedback in general, irrespective of its valence (Dalgleish et al., 2017).
Previous experimental studies have thus indicated that different neural processes can be distinguished for social acceptance and rejection in adults and adolescents, but there remain many unanswered questions. Until now the paradigms to study social acceptance and rejections have not been consistently applied to children and young adolescents and there has been little emphasis on behavioral outcomes. To really understand the effects of social acceptance and rejection on children and their development we need a new approach, with a targeted experimental paradigm. Prior studies have provided a solid foundation for studying social evaluation, but an important next step is to disentangle between neural activation that is related to general social saliency and neural activation that is specific for negative social feedback. Understanding the latter
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