Proportionality in Criminal Sentencing: A Cognitive Hypothesis

Research into the cognitive psychology of proportionality—here, the familiar idea that the severity of the punishment should reflect the severity of the crime—can enrich the study of US criminal sentencing and identify new connections between research in law, psychology and philosophy. This article presents a cognitive-psychological model of proportionality and shows how the model helps to illuminate the behaviour of a range of sentencing decision makers. According to this model, the way in which people tend to mentally represent and compute proportionality means that the latter has at least two behaviourally important features: it is both cognitively intuitive and difficult non-arbitrarily to apply to prison sentences, in well-defined senses of those terms. The interaction between these two features helps to account for data points such as the following: (i) why the original US Sentencing Commission tried to, but did not, base the US Sentencing Guidelines on a retributivist rationale; (ii) why sentencing decision makers are likely to have political-rhetorical flexibility in deciding whether to use the concept of proportionality; and (iii) why several federal judges have observed that sentencing decision makers are susceptible to anchoring. Attending to the psychology of proportionality also yields normative implications and suggestions for future research.