日本認知心理学会

Yama et al. (2017) reported hindsight bias in perceptions of the muddiness and the predictability of a flash flood in a river, as part of the author’s expert testimony in a court trial. The defendants had taken children to the river to play when a flash flood occurred that led to the drowning of one child. The core question was if the defendants could have predicted the flood using a visible cue: the muddiness of the river. Participants who knew the outcome of flash flood estimated the river muddier. The instruction on causality between the muddiness and the flush flood was manipulated in this current study. Participants were grouped into two conditions: the control condition and the outcome condition. The hindsight bias was confirmed and participants judged the river as muddier when the causality was instructed. These data give practical indications for legal judgments in a court.