Tuesday, January 14, 2014

Does Criminal Law Deter? (Part Two)



(Part One)

This is the second in a two-part series looking at Robinson and Darley’s article “Does Criminal Law Deter? A Behavioural Science Investigation”. It is commonly thought that changes to the substantive criminal law (i.e. the rules about counts as a crime and how much punishment should be attached to the commission of crime) can have a deterrent effect. At least, many policy debates and legislative changes proceed on that assumption. But how plausible is it really?

Robinson and Darley argue that it isn’t. While they accept that a criminal justice system, with conspicuous mechanisms of enforcement, can have a deterrent effect, they argue that it is unlikely that the substantive criminal law adds to that effect. And, certainly, the effects are nowhere near as fine-grained or precise as policy debates would typically have us presume.

As reviewed in part one, their argument for this conclusion is fairly simple. They claim that in order for the substantive criminal law to have a deterrent effect, three conditions must be met: (i) the knowledge condition, according to which potential criminals must know what the law demands; (ii) the immediacy condition, according to which potential criminals must be able to bring that knowledge to bear on their crime-relevant decisions; and (iii) the weighting condition, according to which the perceived costs of crime must outweigh the perceived benefits.

Robinson and Darley think it unlikely that all three of these conditions can be met. This means their argument looks something like this:


  • (1) In order for the substantive rules of criminal law to have a deterrent effect, three conditions must be met: (i) the knowledge condition; (ii) the immediacy condition; and (iii) the weighting condition.
  • (2) It is highly unlikely that the knowledge condition is met.
  • (3) It is highly unlikely that the immediacy condition is met.
  • (4) It is highly unlikely that the weighting condition is met.
  • (5) Therefore, it is highly unlikely that the substantive rules of criminal law have a deterrent effect.


We reviewed the case for premises (2) and (3) the last day. Today we’ll look at the case for premise (4).


1. The Rational Choice Model and the Weighting Condition
The deterrence assumption tends to work with a rationalistic approach to criminal behaviour. That is to say, it tends to presume that criminals make decisions about whether or not to commit a crime based on an analysis of the costs/benefits of the crime. We’ve already looked at ways in which this model of criminal behaviour could be flawed: if the knowledge and immediacy conditions are not met, then potential criminals won’t be able to engage in the kind of cost/benefit analysis required by the deterrence assumption.

Still, there is a distinction to be made between two kinds of rational choice model of criminal behaviour. The first, which focuses on the actual costs and benefits the crime, and the second, which focuses on the perceived costs and benefits. Any model focusing on the former is likely to be well off the mark, since potential offenders may not be able to appreciate the actual costs and benefits. But a model based on the latter could get off the ground, since the perceived costs and benefits are what (presumably) guide any particular decision.

Robinson and Darley’s discussion of the weighting condition focuses on the perceived costs and benefits. They hold that the following inequality is needed if the deterrence assumption is to prove correct:

Perceived Cost of Crime > Perceived Benefit of Crime

Furthermore, and following a suggestion originally put forward by Jeremy Bentham, they argue that the perceived cost will depend on three variables:

Perceived Cost = [Probability of Punishment][Delay of Punishment][Total Amount of Punishment]

In other words, perceived cost is a function of the total amount of punishment, times the probability of being punished, discounted by some delay factor.

Their claim is that behavioural science has revealed that the effect of each of these variables on perceived cost is far more complex and (sometimes) more counterintuitive than is often believed to be the case. They support this by looking at a range of studies. Of course, as they note at the outset, good controlled studies on the effects of each variable on perceived cost are hard to come by: researchers are not permitted to punish research subjects as severely as we punish criminals in the real world. But it is possible to draw some conclusions based on animal studies, experiments involving punishments of moderate intensity (that subjects have consented to) and “natural” experiments.

So let’s look at the evidence.


2. Evidence Relating to the Probability of Punishment
When it comes to assessing the impact of punishment probabilities on behaviour, Robinson and Darley turn to conditioning studies. These are the classic animal-in-a-box experiments, which were so heavily associated with the behaviouralist movement in psychology. The typical set-up in such an experiment is that an animal is trained to perform (or already predisposed to perform) some kind of action (e.g. pressing a button), and this action is then linked to some punishment (e.g. a mild electric shock). In this experimental set-up, it is easy to vary the rate of punishment and see what effect this has on discouraging the action.

Such that have been done on this suggest that once the probability of punishment drops below a certain threshold, it has practically no deterrent effect. For example, in classic studies by Azrin, Holz and Hake it was found that a 10% punishment rate failed to suppress behaviour.

One problem with these studies, however, seems to have been that the punishments were not randomised (i.e. the punishments occurred at regular intervals) and, apparently (I have not confirmed this), studies involving randomised rates of punishment are hard to come by. But, reviewing the few that have been done, Lande found that there was less suppression of behaviour as the probability of punishment declined. Furthermore, he found that there were “response bursts” after punishment. In other words, the experimental subjects engaged in more of the relevant behaviour after having been punished. This may be because they indulged in something akin to the gambler’s fallacy, i.e. they assumed they were much less likely to be punished “the next time round”.

You can imagine where all this is going. Robinson and Darley argue that these studies have worrying implications for the criminal law. Citing actual conviction rates (across all crimes) of 1.3% in the U.S. and single digit punishment rates for even the most serious of crimes, Robinson and Darley suggest that the criminal law may have minimal deterrent effect. This is because the actual punishment rate is below the rate at which it will have a deterrent effect. They also cite anecdotal cases in which a criminal committed a crime just after having been punished, which seems to confirm Lande’s finding of “response bursts”.

So Robinson and Darley seem to support the following argument:


  • (6) If the punishment rate drops below a certain threshold (maybe 10%), the criminal law will not have a deterrent effect and may also have perverse effects (e.g. it may lead to “response bursts”).
  • (7) The actual punishment rate is below this threshold.
  • (8) Therefore, the criminal law will not have a deterrent effect.


There are a several criticisms one could make of this argument. Robinson and Darley only address the most obvious: what if people overestimate the rate of punishment? What if people think the punishment rate is above the relevant threshold? They respond to this critique by suggesting that many potential criminals will suffer from overconfidence bias, and by pointing to David Anderson’s study (discussed in part one) of actual criminals’ attitudes toward punishment. Anderson found that 76% of active criminals and 89% of the most serious offenders either did not think they would be caught or didn’t even consider the possibility of punishment.

I have some other problems with the argument. First, I think it hangs too much on animal conditioning studies. More human data would have been nice (the studies on actual criminals’ attitudes toward punishment are welcome in this respect). Second, the relevant thresholds are little too vague for my liking. And third, I think the argument diverges too much from the original thesis of Robinson and Darley’s article. Their original claim was about the deterrent effect of the substantive criminal law. But this argument really has to do with the effectiveness of the criminal justice system as a whole, not the rules of criminal law. This is surprising given that they originally supported the deterrent effect of the criminal justice system as a whole.


3. Evidence Relating to the Amount of Punishment
One of the assumptions shared by proponents of the deterrence hypothesis is that fine-grained modulation of the total amount of punishment attaching to an offence can make a real difference to how frequently that crime is committed. Thus, for example, increasing the sentence length for theft from five to ten years in prison is thought to make a difference to behaviour. One can see the attraction of this assumption. Simple cost-benefit reasoning tells us that ten years in jail is worse than five years in jail (approximately twice as worse), ergo potential criminals should think twice as hard about committing theft if the sentence is increased to ten years.

As attractive as this reasoning is, there are several problems with it. Again, the all-important factor here is how increases in the duration or amount of punishment are perceived by potential criminals, not what the reality is. Behavioural evidence suggests that these perceptions may be out of line with reality. Robinson and Darley review several strands of evidence in support of this contention.

They start with conditioning studies. The primary conclusion from these studies (they mention a few) is that increases in the severity of punishment do indeed increase deterrence. But there are some interesting nuances. It has been found that animals can adapt to the intensity of punishment. Thus, for example, you could start out giving a pigeon electric shocks below 60 volts and then gradually increase it, even up to 300 volts, and find that the pigeon continued with the behaviour you were trying to deter. This would not be true if you started out punishing at the more intense level.

This doesn’t bode well for the criminal law. It is common for first-time offenders to given more lenient punishments. Indeed, sometimes their punishments are completely suspended. This may create the conditions in which an “adaptation to intensity”-effect can flourish. Furthermore, it’s not just animal studies that support this view. In a famous paper by Brickman and Campbell, it was suggested that human experience of affective changes follows something like a “hedonic treadmill” in which there is gradual adaptation to a new affective baseline. So, for example, what was initially experienced as intensely pleasurable gradually becomes less so as the experiencer adjusts to the new “baseline” level of pleasure.

Robinson and Darley argue that two distinct types of adaptation could occur in the prison environment: (i) neutralisation; and (ii) hardening. The first type of adaptation arises when the prisoner adjusts their affective baseline to cope with what was initially felt to be a highly punitive state. Thus, the punitive effect of, say, prison is neutralised over time. This means that they will continue to experience positive and negative changes to their affective state, but those changes will be relative to the new (lower) baseline. They cite in support of this claim studies showing that the risk of suicide among prisoners is much higher in the first 24 hours of incarceration. “Hardening” is a different process, whereby the prisoner just becomes more immune to changes in their affective environment. Thus, as they go along, they are less affected by positive and negative events. Both of these types of adaptation could undermine the deterrent effect of punishment, particularly imprisonment, for repeat offenders.

Another problem has to do with the discrepancy between remembered pain and the actual duration of a punitive experience. Research by Daniel Kahneman and his colleagues suggests that remembered pain is not simply a direct function of the duration of pain. Instead, it seems to be a function of the most intense pain experienced and the most recent painful experience. The result being that short, but intensely unpleasant, punishment is remembered as being much worse than long, moderately unpleasant, punishment. This lends credence to the deterrent powers of the classic “short, sharp shock” approach to punishment, and detracts somewhat from the contemporary obsession with duration of prison sentence.

The upshot of all this is that there are diminishing deterrent returns to be had by increasing the duration of punishment, and maybe no returns at all to be had from modulating the severity of the punishment in proportion to the gravity of the offence and the offender (due to adaptation effects). This is not to say that there aren’t sound moral reasons for modulating punishment in this manner (proportionality still feels like it is morally justified); but it is to say that such moral reasons are not easily grounded in deterrence.

One criticism of this argument is that it seems to dwell upon the deterrent effect of punishment on those who are undergoing or have undergone it (“special deterrence”) and not on the deterrent effect on the general population. Robinson and Darley wave this objection off by arguing that many of those who commit crimes are repeat offenders. But, unfortunately, that still doesn’t address the criticism. The general population will not have been privy to the kinds of experiences that lead to adaptation effects, so maybe they could be genuinely deterred by increases in the total amount of punishment? The discussion of discounting (below) may provide some response to this criticism.

Robinson and Darley also go on to argue that the social milieu from which many offenders are drawn can affect how they perceive the total amount of punishment. Many are socialised in an environment in which “doing time” is common among their peers, and the potential costs are consequently downplayed. Furthermore, many come from deprived backgrounds and so the costs of punishment may seem much less to them than to someone from a more affluent background. Again, these factors may combine to undermine the deterrent effect.


4. Evidence Relating to the Delay of Punishment
The final factor that affects the perceived cost of punishment is the delay between carrying out the act that is to be punished and the actual administration of punishment. Robinson and Darley are brief on this point since the behavioural evidence seems to be pretty clearcut: a combination of conditioning studies and cognitive psychology experiments indicates that the greater the delay between the act and the punishment, the lesser the deterrent effect.

Perhaps one of the most widely-popularised models of this argues that humans (and other animals) hyperbolically discount the value of future rewards (and losses) relative to more immediate rewards and losses. In other words, they prefer “smaller sooner” rewards to “larger later” rewards. This is thought to account for addictive behaviours like cigarette smoking. Even though people are often aware of the long-term costs of smoking, and the long-term rewards of not-smoking, their internal valuation mechanisms are such that the immediate reward of smoking seems more attractive than the long-term reward of quitting. The diagram below provides a representation of hyperbolic discounting curves for human preferences. Note how the value of the smaller reward exceeds that of the larger reward at a certain point.




The relevance of this to criminal behaviour and punishment should be obvious. Since there is often a significant delay between the commission of a crime and the punishment (if any) of that crime, the short term rewards of the crime will often seem more attractive to a potential criminal than the long-term costs of the punishment. Consequently, the delay undermines the deterrent effect.

I think Robinson and Darley are probably correct about this, however, I can’t help but point out that this, once again, has more to do with the criminal justice system as whole than it does to do with the substantive criminal law. After all, substantive criminal laws tend not to stipulate that there must be a significant delay between the commission of crime and the imposition of punishment.


5. Conclusion
Okay, so that brings us to the end of Robinson and Darley’s argument. To briefly recap, their central thesis is that the substantive criminal law is unlikely to deter criminal behaviour. This is because in order for the substantive law to have a deterrent effect it must satisfy three conditions: (i) the knowledge condition; (ii) the immediacy condition; and (iii) the weighting condition. Drawing from a range of behavioural science research, Robinson and Darley argue that it is unlikely that all three conditions are met.

Their argument is plausible, and brings together some interesting strands in the behavioural science literature, but it still contains points of weakness. The most annoying of which is, perhaps, its tendency to stray from the central thesis — which was supposed to be about the substantive criminal law — into more general concerns about the criminal justice system.

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