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Prolonged vacation and the dangers of diet soda July 25, 2007

Posted by Johan in Links, Rants, You Make Pearson Cry.

The blog has been idle for long enough for the spam bots to kick in properly – I can only surmise that they specifically target blogs with no recent post since there is less risk of moderation that way.

My vacation is still on, now in Budapest, Hungary. What little time I have for science is spent re-learning high school maths for the GRE and reading up for a literature review on face processing in Schizophrenia.

I was going to post a quick rant about the recently hyped-up story on how diet soda is linked with ‘metabolic syndrome’ (heart disease, diabetes and other consequences of poor eating), just like regular soda. There are some obvious problems with how the media has interpreted the correlational, non-causal relationship between metabolic syndrome and diet soda consumption, e.g., could it be that people who drink a lot of diet soda do so at fast food restaurants and in other contexts where you might eat unhealthy foods?

However, Shelley at Retrospectacle already posted an excellent critique of the study. I really have nothing to add, so go read about it at Retrospectacle instead.


Big brother knows best? Maybe not June 24, 2007

Posted by Johan in Behavioural Genetics, Developmental Psychology, Rants.
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As a big brother, it is tempting to accept the conclusions that Kristensen and Bjerkedal (2007) draw in their recent article in Science. According to these researchers, IQ is associated with birth order, more specifically social birth order. This measure was created by looking at families where the oldest sibling had died, thus leaving what was biologically the middle child as the “social big brother” (note that the IQ data comes from army conscripts, so all the tested siblings were male). Kristensen and Bjerkedal found that even in these families, the older surviving sibling tended to have a slightly higher IQ than the younger sibling, as the figure below shows.

Note that differing ages is not a factor here, since all siblings were tested at the same age. Kristensen and Bjerkedal argue that this supports a social interpretation of the IQ difference in terms of the family environment, rather than a biological account based on the notion that the first-born might have experienced a better pre-natal environment.

This story has made the rounds both in the news and in blogs, and generally there is surprisingly little criticism. I think Kristensen and Bjerkedal fail to consider an alternative explanation for their results.

Consider the factors that go into deciding whether you want to have another child or not. It is likely that you will consider your experiences with the child or children you already have. Parents who are not as satisfied with their current child or children are less likely to have another child, and this is likely to work the same way when deciding to have child number two, three, and on.

Note that I’m assuming here that parents will pick up on a child’s IQ and that this trait will express itself relatively early on, before the parents decide whether to have another child. So the data for the non-smart first-borns aren’t represented accurately in this analysis, since their parents didn’t have more kids as often.

But here’s the catch: each time you procreate, your chances of hitting the jackpot (ie, all Smart Kids) decreases. This follows from basic probability: if the chance of having one Smart Kid with your genes is x, the chance of having two Smart Kids (x²) must be smaller, and the chance of all Smart Kids continues to decline in this fashion. You’re playing with the same chromosomes each time, so it’s reasonable to assume that the probability is constant.

So if the parents consider their luck before deciding to have another kid, and if they count their luck in the number of Smart Kids, you would expect IQ to drop off as it does in the figure above. Parents who have a first Smart Kid are more likely to have a second child, and parents who have two Smart Kids are more likely to have a third. But with each new child, the chance of the jackpot (all Smart Kids) declines.

To summarise: The parents’ decision to have more children is determined in part by the IQ of the existing children, which means that more intelligent children are also more likely to have younger siblings. But conversely, this selection won’t operate on the youngest child, and will operate to a lesser extent on middle children.

With this account of the data, there is nothing particularly surprising about Kristensen and Bjerkedal’s essential finding that the social big brother (ie, the middle sibling) is smarter than the third sibling. You would expect this, given the interaction between the genetic lottery and the parental choice to procreate.

Let me refute one criticism that could be raised against this account: You might think that the younger siblings in families where the first-born died should have about the same IQ as the younger siblings in families where the first-born didn’t die. This is not the case, as a comparison between the black and the green dots in the figure above shows.

Before you conclude anything from that, look in the supplements for the article. You will find that Kristensen and Bjerkedal restricted their dead first-born sample to cases where the first-born was stillborn, or had died before the age of 1. So maybe the first-born simply wasn’t alive for long enough for the parents to base their further procreation decisions on the smartness of this kid. If this is true, the same parental decision-making process that would normally be based on the first-born is now based on the second-born: Smart Kids are more likely to get younger siblings, while not so Smart Kids are less likely to have younger siblings.

It’s worth emphasising that these are subtle effects. The difference in this study was around 3 points (M=100), so while my discussion of Smart Kids and not so Smart Kids above may sound categorical, I’m only trying to make my point salient. Even if my little theory above is correct, IQ is likely to only play a small role in whether parents choose to procreate or not – otherwise, we would see larger effect sizes in studies such as this one.

If nothing else, I think this study highlights the issue of effect sizes in psychology. Is an IQ difference of 3 points worth discussing? What is the relevance of such a small effect? Can it form the basis of policy changes, or advice to parents? Surely not. I’m not even sure if it has theoretical relevance – surely there are factors out there that explain a bigger part of the IQ variability, and where the exact underlying causes are equally unknown. Yet, this study is treated as if it is hugely important. Look at the quotes below from the New York Times, for instance:

Three points on an I.Q. test, experts said, amount to a slight edge that could be meaningful for someone teetering between an A and a B, for instance, or even possibly between admission to an elite liberal-arts college and the state university, some experts said. They said the results are likely to prompt more intensive study into the family dynamics behind such differences.

“I consider this study the most important publication to come out in this field in 70 years; it’s a dream come true,” said Frank J. Sulloway, a psychologist at the Institute of Personality and Social Research at the University of California in Berkeley.

The edge between liberal-arts college or state university? The most important study in the field for the past 70 years? Don’t believe the hype.

Kristensen, P., Bjerkedal, T. (2007). Explaining the Relation Between Birth Order and Intelligence. Science, 316, 1717.

Now I remember why I went abroad to study May 14, 2007

Posted by Johan in Off Topic, Rants.
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The Moralist. Excerpt from Ship of Fools (Brandt, 1498)

There’s a bit of drama in the Swedish news about the psychology department at Gothenburg University (story here, here, and here, for those who speak Swedish). Apparently, the department discovered that one of their undergrads had appeared as a page 3 model in a Swedish lads’ magazine, which caused them to, well, go psychotic.

The department demanded that the student attend psychotherapy with a member of faculty, and that she apologise in front of her entire year. They then barred the student from going on work placement (which all the other students in her year were doing), leaving her to work in the department (presumably photocopying and boiling coffee).

When confronted about this unusual reaction, the head of the department, Erland Hjelmquist, argued that her future position as a therapist would be compromised if she was recognised from the pictures (which is perhaps not entirely unreasonable, although unlikely), but then he said… I’ll just translate the last bit for you: “[her appearing the magazine] raises questions about her way of reflecting on the content of the course, and how one relates to one’s self concept.” (italics added)

Apparently, women who take their clothes off in lads’ mags need therapy, must apologise for shaming themselves, and have damaged self concepts. It is also clear from the Gothenburg U psychology course content that taking your clothes off in a magazine is deeply psychologically damaging and inappropriate (I’d like to see their textbooks!).

I wonder how Dr Hjelmquist would react to the fact that a few U of York undergrads are financing their education by dancing in clubs…

The striking thing is that Sweden is a profoundly atheistic, tolerant country. We pride ourselves on having liberal laws on abortion, gay rights, and other social issues. Yet, there is a moralistic undercurrent. A student in a lads’ mag causes an outrage, much like it would at a Christian university in the US or at a private school in the UK, but the outrage is not fueled by religious values – instead it’s fueled by some kind of misguided authoritarian feminist dogma.

This woman isn’t being ostracized for her sins, she is ostracized for contributing to the patriarchal objectifying of women. According to this dogma, any woman who sells her body, dances in a club, or poses for pictures is probably a victim of sexual abuse, and is only doing what she does because she is self-destructive and has a low self-esteem (ie, her self concept is off). This is why the student needs therapy – to address the underlying trauma that must have caused her to behave this way.

Still, it’s most likely that the people in the Gothenburg psychology department who dealt with this would be deeply offended if anyone dared call them moralistic or conservative. It’s curious that the outcome of a profoundly leftist, progressive ideology is in fact the very same intolerance that you normally expect to find on the far right.

Finally, a disclaimer: I am a feminist. In no way am I saying that feminism by definition is an authoritarian dogma. Feminism is a belief in the equal value of men and women, and its corollary is that society should reflect this equality. The authoritarian dogma I outline above has, by that definition, little to do with feminism.

The Weight of Recovered Memories March 7, 2007

Posted by Johan in Developmental Psychology, Rants.
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In a current trial in Portsmouth, a sailor has accused another sailor of rape, after recovering memories of the event in therapy. The sailor recovered these memories a few weeks after the events allegedly took place, with the help of a technique called Eye Movement Desensitisation and Reprocessing (EMDR). As I understand it, EMDR is based on psychoanalytic ideas about traumatic memories being insufficiently or inappropriately processed, and stored in an isolated network – a fancy re-writing of the concept of Freudian repression, you might argue. The exact method of therapy goes something like this:

[…] the client attends to the disturbing memory in multiple brief sets of about 15-30 seconds while simultaneously focusing on the dual attention stimulus (e.g., therapist-directed lateral eye movements, alternate hand-tapping, or bilateral auditory tones). Following each set of such dual attention, the client is asked what associative information was elicited during the procedure. This new material usually becomes the focus of the next set.

Almost sounds plausible, until you realise that it’s actually good old free association, given a fancy new outfit.

The striking thing about the BBC story is that apparently, courts are still considering testimony from people who claim recovered memories, after all the controversy. Part of the reason why psychoanalysts are able to insist that the possibility of recovered memories is an open question is that the basic premise is very hard to test. Most recovered memories are not of the kind that are easily corroborated. It would probably be unethical to subject people to traumatic experiences and later check if they have repressed the memory of it.

Still, a paper by Clancy et al (2000) suggests that to at least some extent, impressionability plays a role in these cases. Clancy et al recruited 4 groups of participants: One group reported recovered memories of sexual abuse as children, another group believed they had been victimised but had no memories, a group that had been victimised and had always remembered, and finally a group with no memories of sexual abuse. The participants performed a task where they were presented with lists of semantically associated words, after which recognition for these words was measured. Crucially, the recognition test contained several items that were semantically related to the items in the lists, but had not actually been presented previously.

The group who claimed to have recovered memories of sexual abuse had the highest false alarm rate, that is, they were more inclined than the other groups to develop an illusory memory of having seen the related words before. It need not be spelled out that the implications are pretty damning for those who believe that false memories are generally genuine.

However, it’s still worth emphasising that group level data are not necessarily applicable to the individual. While the results by Clancy et al suggest that individuals with recovered memories appear to be more suggestible than others, this does not necessarily hold true for all cases. There have been cases where recovered memories have been corroborated by other evidence quite convincingly, most famously perhaps the case of Ross Cheit, a professor of political science at Brown University who recovered memories of sexual abuse as a child. Cheit was able to confront his attacker and obtain a confession, which he then used to prosecute his tormentor, almost 30 years after the events took place (for a full account, see Shacter, 1997).

So to conclude: while it would be unreasonable to reject recovered memories outright, we do have a problem if they are given more weight than other testimony, and problems of suggestibility have to be considered. Due to the nature of memory recovery therapy, where the patient is often helped by the therapist to produce an elaborate and consistent story, testimony may appear stronger than it would otherwise.

Therapists focusing on this area are most certainly quacks, regardless. It’s noteworthy that Cheit, the classic example of the reality of recovered memories, had his own realisation spontaneously, without seeing a therapist.


Clancy, S.A., Schacter, D.L., McNally, R.J., & Pitman, R.K. (2000). False Recognition in Women Reporting Recovered Memories of Sexual Abuse. Psychological Science, 11, 26-31.

Shacter, D.L. (1997). Searching for Memory: The Brain, the Mind, and the Past. New York: Basic Books.


Apparently the sailor was convicted.

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.