Best to Be Last : Serial Position Effects in Legal Decisions in the Field and in the Lab

Experts and workers in many domains make multiple similar but independent decisions in sequence. Previous research has shown that the serial position of the case in the sequence, an irrelevant factor, often influences the decision. Yet, the conditions under which serial position effects emerge remain unclear. Explanations for these effects tend to focus on the role of decision makers’ fatigue, but these effects emerge also when fatigue is unlikely. Here, we highlight the importance of considering decision makers’ motivation to produce consistent sets of decisions. We focus on the legal domain in which many high-stakes decisions are made in sequence. We analyze two field datasets: 386,109 US immigration judges’ decisions on asylum requests and 20,796 jury decisions in 18th century London criminal court. We distinguish between five mechanisms that can drive serial position effects and examine their predictions for these settings. We find that consistent with motivation-based explanations of serial position effects, but inconsistent with fatigue-based explanations, in both settings decisions become more lenient as a function of serial position, an effect that persists over breaks and contrasts previous findings concerning sequential parole hearings. We further find the leniency effect is stronger among more experienced decision makers. To complement the analysis, we run controlled experiments with laypeople and find similar results. Theoretically, we suggest that decisions may become more favorable towards the side that is more likely to put a decision under scrutiny. In many contexts, including legal decisions, this process implies that it is often “best to be last”