Behavioral and functional connectivity basis for peer-influenced bystander participation in bullying

Abstract

Recent studies have shown that the reactions of bystanders who witness bullying significantly affect whether the bullying persists. However, the underlying behavioral and neural mechanisms that determine a peer-influenced bystander’s participation in bullying remain largely unknown. Here, we designed a new ‘catch-ball’ task where four players choose to throw a sequence of normal or strong (aggressive) balls in turn and examined whether the players (n = 43) participated in other players’ bullying. We analyzed behaviors with a computational model that quantifies the tendencies of a participant’s (i) baseline propensity for bullying, (ii) reactive revenge, (iii) conformity to bullying, and (iv) capitulation to threat and estimated these effects on the choice of balls. We found only conformity had a positive effect on the throwing of strong balls. Furthermore, we identified a correlation between a participant’s conformity and social anxiety. Our mediation analysis of resting-state functional magnetic resonance imaging revealed that there were significant relationships of each participant’s functional connectivity between the amygdala and right temporoparietal junction (TPJ) and social anxiety to the participant’s conformity to bullying. We also found that amygdala–TPJ connectivity partially mediated the relationship between social anxiety and conformity. These results highlighted the anxiety-based conformity and amygdala network on peer-influenced bystander participation in bullying.

Cue-Reactivity Among Young Adults With Problematic Instagram Use in Response to Instagram-Themed Risky Behavior Cues: A Pilot fMRI Study

“…The advantage of the present study is that it gives a distinct dimension in understanding the neurobiology of social media addiction, particularly the consequences of Instagram use among young adults. This study is also pertinent in giving evidencebased medicine considering that prior experiments using questionnaire-based responses only studied information that assessed the reflective cognitive judgment, whereas fMRI-task behavior can clearly illustrate automatic emotional judgments (Takami and Haruno, 2018).…”

Dissociable Behavioral and Neural Correlates for Target-Changing and Conforming Behaviors in Interpersonal Aggression

“…We included a postexperiment questionnaire to assess the ecological validity of the task, and ;90% of the participants accepted the task manipulation as valid (for further details, see Takami and Haruno, 2019).…”

“…We previously developed a novel catch-ball task similar to Cyberball to examine how participants behave when others start interpersonal aggression and analyzed resting-state functional magnetic resonance imaging (fMRI) data based on behaviors during the task (Takami and Haruno, 2019). The task required four participants play together on individual desktop computers ( Fig.…”

“…Each participant threw eight balls in each session (64 balls in total), and this setting enabled us to examine whether the participants (P2) conformed to laboratory interpersonal aggression or not. We reported that each participant's degree of conformity was correlated with a social anxiety score (and neuroticism score) and not an empathy score, and also that the degree of conformity was correlated with functional connectivity between the amygdala and temporoparietal junction (TPJ) and between the ventral ACC and posterior cingulate cortex (PCC; Takami and Haruno, 2019).…”

“…A detailed task flow is illustrated in Extended Data Figure 1 [Interpersonal Reactivity Index (IRI); Davis, 1983]. We hypothesize that the dACC may play an important role, because this brain structure was revealed to correlate with conformity to interpersonal aggression in our previous study (Takami and Haruno, 2019), with social exclusion in the above catch-ball setting (Kawamoto et al, 2012) and with behavioral switching in foraging tasks (Kolling et al, 2012), which is relevant to bistrategic behavioral choices.…”