Omission Bias in Adolescence: Asymmetric Perceptions of Morality, Intentionality and Causality

Humans are more tolerant of omissions than commissions when both cause similar negative outcomes, which is defined as omission bias. Although adults show omission bias in various moral contexts, it remains unclear how omission bias develops from adolescence to early adulthood. The current study aims to examine how adolescents perceive morality, intentionality, and causality of commissions and omissions.

We recruited 730 participants from junior and senior high schools, as well as universities, between 2022 and 2023. Participants came from three provinces (Beijing, Shanxi, Henan) in China, including 160 early adolescents (M_age = 12.55 ± 0.34 years, 74 females), 169 middle adolescents (M_age = 13.71 ± 0.71 years, 74 females), 223 late adolescents (M_age = 17.15 ± 0.60 years, 123 females), and 178 young adults (M_age = 21.75 ± 1.81 years, 123 females). We conducted a 2 (Behavior: commission, omission) × 4 (Age: early adolescents, middle adolescents, late adolescents, young adults) × 2 (Outcome: harm, no harm) analysis of variance with morality, intentionality, and causality ratings as dependent variables respectively.

The results indicated late adolescents and young adults regarded commissions as more immoral than omissions. This tendency was consistent with the asymmetric perceptions of causality in the same age groups, but not with the asymmetric perceptions of intentionality, which existed even in early adolescence.

These findings suggested that omission bias becomes more pronounced in middle-to-late adolescence and causality perceptions may play an important role in omission bias on moral judgment.