Between his best-selling books, The 4-Hour Workweek, The 4-Hour Chef, and the 4-Hour Body, as well as a podcast, an iTunes TV show, and numerous high-paying speaking and consulting gigs, Tim Ferris has made a lucrative business out of teaching people ‘accelerated learning’, but does the purported efficacy of accelerated learning hold up to scrutiny?

Here is an audio excerpt from The 4-hour Chef posted on Tim’s blog in which he discusses some of his techniques for accelerated learning. 16 minutes into the podcast he describes how taking a ‘nootropic’ allowed him to get a perfect score at Princeton on a Mandarin test after only a few minutes of study ‘skimming the pages of the study material as quickly as he could turn them and retaining everything’. The major problem here is that this is not a scientific study, rather a single anecdotal example, and one that doesn’t control for a multitude of factors. Assuming this story is even true, photographic memory has more to do with having a very high IQ and or ‘savant abilities’ (which are still a mystery to scientists) than purported efficacy of ‘mind drugs’. You would need a randomized trial that controls for IQ, and I imagine under such conditions individuals with mediocre IQs would perform more poorly on learning and memory tasks than more intelligent test participants, regardless of dosage. I also suspect in a randomized, double blind study there would be little improvement across all intelligence levels, that is statistically significant from a placebo.

Many of these drugs are just stimulants, but being stimulated doesn’t necessarily boost learning performance where it matters most (retention, recall, and speed).

From lifehacker: How Effective Are Nootropics and “Smart” Drugs?

In fact, in a 2014 systematic review of 11 different studies, published in the journal Nutrition Review, researchers found that use of caffeine in combination with L-theanine promoted alertness, task switching, and attention. The reviewers note the effects are most pronounced during the first two hours post-dose, and they also point out that caffeine is the major player here, since larger caffeine doses were found to have more of an effect than larger doses of L-theanine.

But alertness is not the same as actual learning and retention.

And from thehustle.co, Nootropics: What Happened When I Went 30 Days On Smart Drugs?,the modest results didn’t justify paying $50 a month.

It’s hard to know how much of the gains are attributable to nootropics, versus just practice and repetition.

As you can probably tell, I’m skeptical that learning ability can be taught or improved, whether it’s Tim Ferris and his books and podcasts on accelerated learning, Kevin Trudeau and ‘speed reading’, or Cal Newport and his ‘college guides’. As is almost always the case, the people writing these guides have vastly superiors IQs (and individual success is generalized as being applicable to the entire population, when in reality such success is attributable to IQ, not ‘special techniques’). Newport, for example, getting a PHD in a hard science at a relatively young age from a prestigious university. The reality is, because working memory is a component of IQ, less intelligent people typically learn slowly and retain little, and there are no ‘hacks’ or drugs that can change this, sorry (or at least none that meet the rigor to be published in a reputable journal). If these drugs worked, everyone would be using them, especially in our super-competitive economy where every point of IQ translates to money…they would be as ubiquitous as shoes. The military would be buying nootropics by the crateload to get recruits to speed. Same for schools…there would be no need forhours of homework every week and years of classes…just pop some nootopics and get a perfect score after flipping through the book a few minutes (as Tim supposedly did). It would be awesome if it worked…years of schooling could condensed into weeks and the economy would get such a huge boost in productivity that Type 1 civilization status would be attainable in years, not centuries.

‘Speed reading’ and other forms of brain training also likely doesn’t work. You can read faster and retain more, but only if you’re smarter (again, a function of IQ), and what is considered speed reading is often just skimming. Studies have shown that comprehension deteriorates at reading speeds higher than 500 words/minute. The reason why speed reading courses can purport success is because they have readers take quizzes to recall stuff they read, but such quizzes don’t test for comprehension, which is not the same as recall. For example, a speed reading course may have the reader read a passage about trains and then have the reader take a quiz recall what the passage is about, among multiple choices that are obviously wrong. The differences between recall and comprehension are explained in more detail here. But even rote recall, such as digit span, is positively correlated with IQ.

Additionally, the specific type of skill one is trying to acquire also matters. Tim frequently cites mastery of swimming, cooking, dancing, and martial arts as examples of accelerated learning, but many of these skills involve ‘muscle memory’ and ‘fluid learning’, not necessarily raw intellect. Psychologists distinguish between ‘crystallized intelligence’ and ‘fluid intelligence’ – the former involves memorization of past experiences and knowledge (vocabulary, math concepts, etc.); the latter involves processing new information, such as pattern recognition. Tim’s techniques may be more amenable to the latter, not the former. Trying to apply accelerated learning to quantum mechanics would probably be a huge failure for most people, whereas much more success would be had with cooking or dance.

In the podcast Tim cites other stories and examples of his success, but oddly enough there are a dearth of stories from actual normal people who have had success, as is almost always the case with these self-improvement gurus.