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The Supposed Irrationality of Crime February 15, 2007

Posted by Johan in Cognition, Forensic Psychology, Rants.
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I read an interesting article by Stephen Dubner on the infamous silver thief Blane Nordahl. Nordahl is famous for high extreme skill in burglary, marked by meticulous precision and a seemingly uncanny ability to evade authorities, but he is also known for his single-minded penchant for silver. This may sound eccentric, but in reality, it is not a bad idea. As Dubner outlines, silver is hard to trace, and can be extremely valuable if you know what to look for. It also has the advantage of being available downstairs in most homes, thus reducing the risk of waking anyone by coming too close to a bedroom.

The article is well worth a read for sheer entertainment, but I think there is also a wider point, which Dubner touches on here:

If an economist were to analyze Nordahl’s operation, he might well be impressed. Economics is, at root, the study of incentives, and Nordahl had rationally concluded that the incentives for stealing silver easily trumped the incentives to stop. He was essentially a one-man economy, and he had pinpointed a valuable yet abundant commodity. Perhaps most important, Nordahl had found a weakness in the criminal-justice system. Robbery was a shrinking discipline-burglary rates have fallen by half since the early nineteen-eighties-and the jail sentences were light.

A psychiatrist, however, might argue that Nordahl was driven by an irrational compulsion. One former girlfriend of Nordahl’s told me that he was fixated on stealing every night. “He got high off it,” she said. “He liked going into houses when people were sleeping. He said it’s more exciting to go into a house when people are there and get away with it.” Lonnie Mason also described Nordahl’s behavior as an addiction: “This is what he exists for, and it’s all about his infatuation with money.” Mason argues that silver was particularly appealing to Nordahl because it connotes the sort of family that passes along precious things from one generation to the next-a family that was distinctly unlike Nordahl’s own. As Mason sees it, Nordahl remained embittered by his parents’ divorce; he resented his father and became extraordinarily close to his mother.

I would have to side with the economist on that one.

There is a striking assumption, often made in criminology and forensic psychology, that crime is irrational. This notion is best exemplified by the cognitive restructuring programs offered to criminals predominantly in Canada, but increasingly also elsewhere. The idea is that through cognitive therapy, inmates will realize that crime doesn’t pay, and that they only thought crime was a good idea because of faulty thinking. Once they understand the true weighting of the incentives, they will understand that refraining from crime is the best course of action, or so the story goes.

Studies evaluating cognitive restructuring-inspired programs in Canada reported some fairly impressive results a few years back; recidivism appeared to have decreased as a result of the intervention. Unfortunately, these studies were flawed by self-selection: inmates who signed up for the program are likely to have been motivated to change to begin with, and furthermore, inmates who did not complete the program were typically removed from analysis. (Unfortunately my Criminology textbooks are in a cardboard box somewhere in Sweden, but if someone takes strong offense at these assertions, do challenge me and I will find you the source).

The problem with the assumed irrationality of criminal behaviour is of course that crime is irrational for most, but not all of us. For me, going on a silverware burglary spree would almost certainly be a bad idea: if caught, I would lose my place at university, ruin my chances at post-grad education, and so forth. It’s pretty clear that while my meager student loan could certainly benefit from a silver spoon or two, the drawbacks of getting caught would be huge.

Not so for Blane Nordahl. No real education, zero work experience, a host of criminal convictions. When he is released from the 8-year sentence he recently received, his options are essentially either going back to doing the crimes that he is so obviously good at, or start flipping burgers (if he can even get that kind of work). I would argue that it in such a situation, filling out a McDonalds application is the irrational thing to do.

But even for less spectacular criminals, the same principle applies. In grade 9, my civics teacher took the class on a trip to a prison, to see an inmate. The person we spoke to was quite obviously addicted to various substances, and had been going in and out of jail with some regularity for the past 20-30 years. No one involved, himself included, thought anything other than that he would go back to burglaries and carjackings when he came out. Given his current situation, with an expensive substance addiction, no work experience, a criminal record, and not knowing a single person who is not also a criminal, it would not just be irrational to try to get a real job, it would be borderline self-destructive.

The notion that crime is a result of irrational behaviour may hold some weight for impulsive, violent crimes, but the bulk of criminal offences are not like that. Most crimes are committed by habitual criminals, who carry out theft, burglaries, muggings. No amount of cognitive restructuring is going to make them think that 2+2 no longer equals 4.


Subliminal Advertising Made Me Do It February 13, 2007

Posted by Johan in Cognition.
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Psychological research on subliminal perception dates back to the late 19th century. In itself, the finding that stimuli that are not consciously perceived can affect subsequent behaviour did not arouse particular public interest or controversy. This changed in the 1950’s, when James Vickary famously reported increased soda and popcorn sales in a movie theatre, following subliminally presented messages endorsing those products during the course of a movie (Loudon & Della Bitta, 1993). While Vickary’s findings were soon discredited as irreplicable, there was great public concern over the possibility that advertisers could induce people to buy products with advertisements that people could not perceive, and thus not assess critically. This resulted in a number of policy decisions limiting the use of subliminal advertising. In popular books of the time, such as The hidden persuaders (Packard, 1981), originally released in 1957, Vickary’s findings were cited uncritically as evidence of the menacing effects of subliminal advertisements. Decades after the original controversy, Zanot et al (1983) found that in an American sample, almost half the participants knew of subliminal advertising, and out of those who knew about it, 68 percent believed it to be effective. Similar results have been obtained more recently (Rogers & Smith, 1993), which suggests that subliminal advertising remains a cause of public concern.

Yet, what is the empirical evidence that subliminal stimuli actually influence consumer behaviour? As we shall see, it is far from clear that subliminal advertising works.

It is important to make an initial distinction between subliminal communication and subliminal persuasion (De Fleur & Petranoff, 1959). Subliminal communication is a well-established psychological finding. For instance, participants were able to guess at better than chance levels which geometrical symbols had been presented subliminally while they watched a movie (De Fleur & Petranoff, 1959). In this task, there is no conflict between how the participants would normally act, and how they act following exposure to the subliminal stimulus. For subliminal persuasion to be effective, the message must do more than this: it must also persuade the participant to produce the desired behaviour.

The ability of advertisements to produce this persuasion effect was tested early on by De Fleur and Petranoff (1959). Two subliminal messages were broadcasted repeatedly on a local TV station: one advertising a certain product, and another advertising a TV programme, which would follow the movie that the subliminal messages had been inserted into. In addition to this, the effect of coupling the subliminal advertisement with a normal, explicit advertisement was tested. The results were a categorical failure of subliminal advertisement to create any discernable effect. Indeed, explicit advertisements actually fared better when presented without the subliminal message. Even the less demanding message, which simply asked participants to remain tuned to the TV station to watch the following programme, failed to produce any significant effects (De Fleur & Petranoff, 1959).

This failure to find an effect in naturalistic settings has not been unequivocally confirmed in the laboratory. Evidence from experiments indicates that participants prefer subliminally presented shapes and faces over previously unseen shapes and faces (Bornstein, Leone & Galley, 1987). In a mock debate between two confederates, participants would side more frequently with the confederate that they had previously been subliminally exposed to (Bornstein et al, 1987), indicating that in this case, subliminal exposure affected social behaviour (note, however, that this particular study has proved difficult to replicate). Likewise, coupling neutral photos of a person with pleasant or unpleasant subliminal stimuli affected participants’ subsequent ratings of the person (Krosnick, Betz, Jussim & Lynn, 1992). Taken together, these findings show that subliminal messages can affect both attitudes and behaviour, in contrast to the findings of De Fleur and Petranoff (1959). Why might these results conflict?

One factor that distinguishes the aforementioned laboratory studies from De Fleur and Petranoff’s (1959) naturalistic study is familiarity. The TV viewers were exposed to subliminal messages endorsing products and TV programmes that they were most likely already familiar with. By contrast, the experimental paradigm relies on stimuli that the participants have never seen before. The increasing appreciation that participants show for familiar stimuli is known as the mere exposure effect (Zajonc, 1968), and as Bornstein et al (1987) found, it extends to subliminal stimuli. It is conceivable that the mere exposure effect is the mechanism that enables subliminal persuasion. Indeed, subliminal stimuli tend to be too simple to offer any arguments, which would limit the efficacy of other forms of persuasion, but not necessarily the mere exposure effect. As shall be shown next, the known limitations of the mere exposure effect may offer some explanation for the differences between the results of naturalistic and laboratory studies on subliminal persuasion.

In his seminal paper on the mere exposure effect, Zajonc wrote:

“[…] in all of these experiments a pattern of results emerges showing that the frequency manipulation has more pronounced attitude effects for stimuli that are novel, unfamiliar, or unusual than for familiar stimuli.” (1968, p. 18)

Thus, under the assumption that the mere exposure effect enables subliminal persuasion, it is not surprising that novel stimuli, such as those used in the experimental paradigm, generate effects, while familiar stimuli, such as those used in the study by De Fleur and Petranoff (1959), do not. Thus, subliminal persuasion is only likely to be effective for novel stimuli, which limits its usefulness for advertising purposes.

Despite this limitation, one paper offers evidence that subliminal persuasion may sometimes offer a unique advantage over explicit persuasion. In a first experiment, Weisbuch, Mackie and Garcia-Marques (2003) assessed their participants’ agreement with a persuasive message, which was attributed to a person whose photo had previously been primed explicitly or subliminally to the experimental groups. It was found that the experimental groups agreed more strongly with the message than a control group that had not been exposed to the photo, but there was no significant difference between the explicit and the subliminal exposure groups (Weisbuch et al, 2003). In a second experiment, the same procedure was followed, except in this case, participants were given a chance to correct for prior exposure: they were simply asked if they had seen the person in the photo before. This caused the explicit exposure group’s agreement scores to drop to the control group’s level, but interestingly, the subliminal exposure group appeared unaffected by this: their agreement levels were now significantly higher than both the explicit exposure group and the control group (Weisbuch et al, 2003). This implies that subliminal exposure can prevent participants from critically evaluating their reasons for agreeing with a message (Weisbuch et al, 2003). Because the subliminal exposure group were unaware of their prior exposure, they could not correct for the biasing effects of it. This inability to correct for prior exposure could prove beneficial for advertising purposes.
The notion that the mere exposure effect could underlie subliminal persuasion has implications that need to be tested. For instance, because the mere exposure effect operates by familiarity alone, the quality of the subliminally presented argument should not matter, so supposing that arguments differing in quality can be presented briefly enough to be perceived subliminally, a weak argument containing the advertised message should have the same effect as a strong argument containing the advertised message.

Bornstein, R.F., Leone, D.R., & Galley, D.J. (1987). The Generalizability of Subliminal Mere Exposure Effects: Influence of Stimuli Perceived Without Awareness on Social Behaviour. Journal of Personality and Social Psychology, 53, 1070-1079.
De Fleur, M.L., & Petranoff, R.M. (1959). A Televised Test of Subliminal Persuasion. The Public Opinion Quarterly, 23, 168-180.

Krosnick, J.A., Betz, A.L., Jussim, L.J., & Lynn, A.R. (1992). Subliminal Conditioning of Attitudes. Personality and Social Psychology Bulletin, 18, 152-162.

Loudon, D.L., & Della Bitta, A.J. (1993). Consumer behavior. Singapore: McGraw-Hill.

Packard, V. (1981). The hidden persuaders. London: Penguin.

Rogers, M., & Smith, K.H. (1993). Public Perceptions of Subliminal Advertising: Why Practitioners Shouldn’t Ignore this Issue. Journal of Advertising Research, 33, 10-18.

Weisbuch, M., Mackie, D.M., & Garcia-Marques, T. (2003). Prior Source Evidence and Persuasion: Further Evidence for Misattributional Processes. Personality and Social Psychology Bulletin, 29, 691-700.

Zajonc, R.B. (1968). Attitudinal Effects of Mere Exposure. Journal of Personality and Social Psychology Monograph Supplement, 9 (2, Part 2), 1-27.

Zanot, E.J., Pincus, J.D., & Lamp, E.J. (1983). Public Perceptions of Subliminal Advertising. Journal of Advertising, 12, 39-45.

Encephalon 16 is out February 12, 2007

Posted by Johan in Neuroscience, Social Neuroscience.
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Over at Mind Hacks. It’s a good one!

I was particularly impressed by a post on emotion and decision-making from Memoirs of a Postgrad. Paul Baxter outlines Damasio’s Somatic Markers Hypothesis, as described in a review by Bechara et al. At the core of this hypothesis (it’s more of a theory, really) is the notion that emotion is central to decision-making. Thus, even though we subjectively experience the decision-making process as rational and detached, we are to some extent going to be governed by emotional responses to the available courses of action. Damasio finds evidence for this primarily in studies on patients who have suffered lesions to the amygdala, thought to play a central role in emotion regulation, particularly of fear. Aside from the usual symptoms of amygdala lesions (e.g., no skin conductance response to a stimulus that is repeatedly paired with electric shocks, no attempts to escape or otherwise avoid unpleasant situations), Damasio points out that his patients are unable to make even the most basic decisions for themselves.

Baxter’s article linked on to a post on the limits of rational thought at Neurontic, which expands on the Somatic Markers Hypothesis.

Look Around You February 11, 2007

Posted by Johan in Off Topic.
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Because every science blog has to link to it at least once:

This is the video that made me want to become a neuroscientist. I must say, it’s been a bit of a disappointment so far… No probes which induce the feeling that you’re about to sneeze, and I haven’t got to hook up a brain to a telephone and feed it brain flakes once.

Sleep Deprivation and the Hippocampus February 10, 2007

Posted by Johan in Neuroscience, Sleep.
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It is quite striking that we currently have no strong account of the purpose of an activity that we all spend somewhere between a quarter and a third of our lives engaging in: sleep. However, it’s not fair to say that we don’t know why we sleep: sleep has been found to affect a range of behaviours. These various purposes that sleep serves may be exactly the reason why a singular account that explains sleep has not been forthcoming. It’s possible that sleep is necessary for several more-or-less independent processes.

Some “creative” functions of sleep such as physical restoration (implausible, as measurable effects of deprivation only appear after extremely prolonged sleep deprivation) and adaptation (in this view, animals are better off sleeping away down-time when they don’t need to feed, as this keeps them out of harm’s way) have been proposed, but the main functions that appear to have tangible effects in experiments concern development and memory.

According to developmental accounts, REM sleep deprivation in developing organisms results in behavioral problems, decreased brain mass, and neuronal cell death. Researchers that focus on the role of sleep in memory suggest that sleep is essential for consolidating information in long-term memory, possibly with relation to emotional content: A recent paper reported on an experiment where participants read texts with emotional or neutral content, followed by three hours of sleep or waking. When testing recognition four years later (!), the participants who had slept immediately after encoding showed a recognition advantage for the emotional stories, but not for the neutral ones (Wagner et al, 2006). Participants who had been awake following encoding showed no such recognition advantage.

Results obtained by Mirescu et al (2006) exemplifies the possibility that developmental and memory accounts are related. In this study, rats were deprived of sleep while their levels of the hormone corticosterone were either held constant or unmanipulated. Mirescu et al (2006) reported that rats who are deprived of sleep in this manner showed reduced cell proliferation in the hippocampus (which appears to be a critical area for encoding events into long-term memory), but this effect was mediated by corticosterone: rats who had their corticosterone levels held constant did not show inhibited cell proliferation. This suggests that sleep deprivation affects normal functioning of the hippocampus, and that corticosterone may be the causative factor… Although this only pushes the question back to what causes corticosterone levels to increase during sleep deprivation. It would be quite interesting to replicate this study in a developmental framework, with memory tests. Sleep deprived rats with constant corticosterone levels may not show the memory impairments that normally appear in rats who have been subjected to extended sleep deprivation.

By the way, it’s worth emphasising that these rats had had no sleep for 72 hours: no effects appeared for rats that had been deprived of sleep for 24 hours. So if you’re wondering if these results suggest that you should start getting more sleep, the answer is probably going to be no, at least not for this reason.


Mirescu, C., Peters, J.D., Noiman, L., & Gould, E. (2006). Sleep Deprivation Inhibits Adult Neurogenesis in the Hippocampus by Elevating Glucocorticoids. Proceedings of the National Academy of Sciences of the United States of America, 103, 19170-19175.

Wagner, U., Hallschmid, M., Rasch, B., & Born, J. (2006). Brief Sleep after Learning Keeps Emotional Memories Alive for Years. Biological Psychiatry, 60, 788-790

Wikipedia: Theories Regarding the Function of Sleep.