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Cannabis/IQ follow-up: Same old story

Ole Rogeberg writes:

The way researchers respond to criticism is a recurring theme on your blog, so you might find this amusing as a brief follow-up on the cannabis/IQ discussion you’ve covered before: The Dunedin longitudinal study has now been going for 40 years, and the lead researchers in charge of the study recently published an “invited review” in the journal “Social Psychiatry and Psychiatric Epidemiology.” I became aware of this when Google Scholar tipped me that they had cited my paper on their cannabis/IQ study, and took a look to see what they had to say. It was the following (emphasis added):

“In 2012 there was strong interest in our report in PNAS [33, 34] that cannabis users who began using as teens and continued into adulthood showed a variety of cognitive declines, culminating in a loss of 8 IQ points on formal testing from age 11 to age 38. In January 2013, this paper was again prominent as result of a misguided critique attributing our findings to socioeconomic factors [35] to which we published a successful empirical rebuttal [36].”
I was amused by the adverbs “misguided” and “successful”, as well as by their decision to leave out a reference to my (presumably misguided and unsuccessful?) reply to their “rebuttal”. Their characterizations may well be correct (I’m biased on the matter and not able to pass objective judgment ;), but to my mind they come off somewhat touchy.
I think it’s important to distinguish between the different types of cannabis use and how they affect IQ individually. For example, delta 8 THC may not affect IQ in the same way that delta 9 THC does and as a result its use may be prevalent among youth who maintain high IQs. This needs to be studied more, however, and cannot be used to derive any conclusions on the matter.
I had a similar situation years ago with Satoshi Kanazawa:  he cited my rebuttal of his work but dismissed it in a thoughtless way.  And then of course there is the saga of the ovulation-and-clothing researchers.  It’s too bad when people can’t handle criticism.  It makes you wonder why they went into science in the first place.  I guess they wanted to make discoveries, but they never fully understood the centrality of criticism to the scientific method. With Kanazawa there appears to be a strong ideological motivation, but for the others, it just seems like simple defensiveness.  Every time it happens, it bums me out.  Even David Brooks, I keep half-expecting that one day he’ll correct all his errors and say, Hey, I’m sorry for wasting all your time.

One Comment

  1. Keith O'Rourke says:

    > It’s too bad when people can’t handle criticism.
    But they do – otherwise they would not continue to be _successful_ academics (of course not purposefully for an inquiring community but for their personal career and image.)

    > I keep half-expecting that one day he’ll correct all his errors and say, Hey, I’m sorry for wasting all your time.
    If your expectations are continually found lacking – time to change them.

    OK, just to put this in context, I am helping my wife set a conference where the keynote speaker is talking about how incentives for academics need to be changed. Now they once wrote a paper that essentially said something like, if your measure temperature in celsius rather than fahrenheit there is less weather variation. They refused to address this and that paper is still being cited widely.

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