T. Kogut and I. Ritov, ‘The singularity effect of identified victims in separate and joint evaluations’, Organizational Behavior and Human Decision Processes 97:2 (2005), 106–16; D. A. Small and G. Loewenstein, ‘Helping a victim or helping the victim: Altruism and identifiability’, Journal of Risk and Uncertainty 26:1 (2003), 5–16; Greene, Moral Tribes, op. cit., 264.