The title of the article in no way reflects the outcome of the research. The study compared measured IQ to a <i>decision to smoke pot</i>. There is no control group, and the study is retrospective.<p>A reader may ask how this result could arise by something other than a cause-effect relationship? Maybe people find themselves under peer pressure to (a) smoke pot, and (b) reject the value of scholarly activities. Someone might answer that IQ is predetermined, that it doesn't have any environmental component. But that idea has been falsified in animal studies, studies that show the development of new brain cells in animals that live in stimulating environments.<p>There are any number of factors that might lead an individual to simultaneously choose to smoke pot and avoid activities that might improve his IQ -- socioeconomic, genetic, and so forth. The only way to control for these things is to design a truly scientific study that <i>tells</i> experimental subjects whether they will smoke pot, rather than <i>asking</i> whether they do. But such a study would be unethical, which is why there's no science in this field of study.<p>This study is much like thousands of studies I've read over about 35 years, and all of them suffer from the same flaw -- they aren't science. Correlation is not causation.<p>The linked study represents psychology at work -- science in name only.
I suspect many will be skeptical of this research as it's almost become an article of faith that pot smoking is harmless and all criticism to the contrary is merely party-pooping oppression.<p>One of the things that often concerns me about Silicon Valley in recent years has been the trend of many startups where pot smoking is part of the established culture of the company. I don't think it's a majority, but it's certainly more than I'd realized previously and it certainly seems to be a more recent trend.<p>I'm not a vehement prohibitionist by any means. However, I've been burned by a co-founder showing up stoned to a key meeting with an investor who'd committed a 6-figure sum out of his own pocket to get the company to where it was. That was a problem.<p>Maybe it's just me aging - I am not a big drinker nowadays, after going through the same college years everyone else did where drinking was involved in so much social activity - but over the years I've arrived at the belief that much of the time wasted stoned, by folks convinced this is making them more creative, is time that could be put to better use.<p>Feel free to do what you want to do, sure. But reminding people that there are negative consequences is never a bad thing.
I was surprised to find out that this study finding comes from a long-running longitudinal study<p><a href="http://dunedinstudy.otago.ac.nz/news/dunedin-study-theme-leaders-win-us1-million-klaus-j-jacobs-research-prize-for-productive-youth-development" rel="nofollow">http://dunedinstudy.otago.ac.nz/news/dunedin-study-theme-lea...</a><p>that has produced some other path-breaking research papers on child development. In other words, while this study is not the last word on the subject of the headline here, it is conducted by researchers who are used to scholarly controversy and having other researchers check their work. So I'll be curious to check the underlying journal article (for which I have yet to see a citation in any of the several news reports about this today).