From witness to reinforcer: a COR-cognitive model of harmful bystander behaviour

Purpose Workplace mistreatment often unfolds in the presence of bystanders, yet existing research focuses primarily on prosocial intervention, overlooking cases in which observers actively reinforce perpetrators. This paper develops a unified psychological framework to explain harmful triadic bystander behaviour, wherein a third-party observer supports, validates or amplifies mistreatment. Design/methodology/approach Drawing on research across bullying, abusive supervision, social influence and third-party reactions, this paper, through conceptual integration, identifies core motivational patterns and maps them onto cognitive appraisal pathways, developing a unified Conservation of Resources (COR)-Cognitive Model to explain harmful triadic bystander behaviour. Findings This paper identifies four recurrent motivational patterns – self-protection, status-utility seeking, moralized judgement and affective reward that drive harmful bystander behaviour. It shows how COR theory links these motives to resource-based decision tendencies and explains how four cognitive pathways, such as threat, calculative, normative and affective cognition, convert these motives into behaviours that escalate workplace mistreatment. Originality/value This conceptual paper offers the first unified psychological explanation of harmful triadic bystander behaviour. By integrating COR theory with cognitive appraisal mechanisms, it moves beyond fragmented findings and reactive bystander models. The framework clarifies why observers actively escalate mistreatment and provides a novel foundation for theory development, measurement and intervention design.