And a tooth for a tooth.

I just finished reading a cute little study by Carlsmith, Darley & Robinson (2002), if by little you mean they had over a thousand subjects. I wish I had those resources! Anyway, the authors are trying to tease apart two different motivations for why people punish - "just deserts" theory, which is motivated by moral outrage and the desire for justice, and deterrence theory, which assumes that potential criminals are rational actors and that the goal of punishment is to make crime the less rational option.



This study relies on the assumption (supported by the authors' own validation study) that certain variables will affect people differently based on their motivations. For instance, if subjects are motivated by deterrence, their decisions on how to punish offenders will be influenced by information such as the detection rate for the crime. After all, if there is a low detection rate, the punishments ought to be more severe, to compensate for how tempting a hard-to-detect crime is to commit. Subject should also desire a high-publicity punishment, as this will act as a greater deterrent. Conversely, subjects who only care about criminals getting their "just deserts" shouldn't be influenced by detection rates or publicity. Instead, their decisions to punish should be determined by the magnitude of harm caused by the offense and whether or not there were extenuating circumstances.

Previous studies have shown that people are most likely to offer deterrence as reason for their punishments. However, subjects do not change the severity of their punishments or their attitudes towards them, even when given evidence that deterrence will not work in that case. Accordingly, the authors set out to test how much of an influence deterrence really had. To do so, they designed a series of experiments using narratives of crimes where the above attributes (detection rate, publicity, magnitude of harm and extenuating circumstances) were varied. They found that manipulation of the deterrence variables had no effect, but that increasing the magnitude of harm or decreasing the extenuating circumstances greatly influenced the severity of punishment, even for those subjects who explicitly stated their preference for deterrence over "just deserts" theories of punishment.

One issue that the authors recognize and address is that the scenario of sentencing an individual, apprehended criminal may limit or even take a person out of a deterrence mindset. Accordingly, in their third study, the authors provided a scenario where the subject was still on the lamb. Subjects were asked to allocate resources either to finding and prosecuting the criminal, or to preventing future crimes. Interestingly, while subjects allocated more resources towards preventing future crimes, they still did not behave as predicted. Low detection rates for a type of crime caused subjects to decrease the resources given to crime prevention when, rationally, that's when it would be most needed. Subjects then went on to replicate the previous studies, changing severity of punishment for criminals only for magnitude of harm or extenuating circumstances.

The study treats "just deserts" theory in a straight-forward manner, declining to dive into the complexities of retribution. Are the subjects motivated by a sense of fairness, or by a desire to get even? The authors speak of "moral outrage" and reference a study that looks specifically at the role of anger, but otherwise leave the motivation-within-the-motivation alone. I would be greatly interested to see the considerable resources of these prestigious psychologists turned towards that question.



Carlsmith, K.M., J.M. Darley & P.H. Robinson (2002). Why do we Punish? Deterrence and Just Deserts as Motives for Punishment. Journal of Personality and Social Psychology, 83, 1-16.