I have to agree with you, I generally find those link-bite "everything you blabla is wrong" titles rather offensive. It a) does not say anything about the content of the article, b) actually insults the reader in a blatant way and c) is a very cheap, offensive and apparently "hip" way of ruthlessly longing for click-throughs. I do not understand how titles like those keep getting up-votes and I feel quite sorry for authors writing good/ok articles and their bosses choosing horrible headings. I am sorry for the "off-topic" rant but it reached a tipping point for me.

Well, clearly titles like this one sell a lot more..

Not understanding the mechanism makes this kind of research very haphazard. For example, his tennis example reflects something that many players already believe, namely that active interference from the conscious mind detracts from learning. (This dates at least back to the 1970s and Timothy Gallwey's "Inner Game of Tennis*.) What strikes me is that the author's mixture of activities would certainly serve the same goal of diverting conscious attention away from the skill being learned. Furthermore, constant conscious attention and reliance on short-term memory would always go hand-in-hand. So the article's observation about mixing activities, your observation about short-term memory, and the widespread folklore about avoiding conscious interference with learning could all have the same mechanism. Until we find the mechanism, we're stuck trying to recreate superficial aspects of these scenarios without understanding why they sometimes produce results. It's the very definition of cargo cult learning.

Ah, is that a reference to Feynman? You criticism is valid but the work being done in the area is certainly not of the phlogiston type. In fact, your criticism applies to much of modern medicine where the systems are so complicated and little understood that we can only catalogue observations, look for statistical correlations, construct simple models, study animal models and back hypothesis with little more than logic and statistical arguments/tests. But things are improving thanks to computers, the ability to solve complex non-linear systems numerically is allowing more mathematical models to be developed for fundamentals. But a unified theory of biological systems is a very long ways away. As more fundamental understanding is developed, the best that can be done is inductive inference. As long as there is good design of experiments, meaningful data being collected and studied and peer review, it is not cargo cult science.

As for your criticism. Spaced repetition is well backed by experiments and centuries of observation and fits with our growing understanding of memory - see Long term potentiation and PKMZeta.

Contextual interference is more tricky as it is not fully understood but it is also long studied. Unlike cargo cult, various hypotheses are being offered, tested and refined. For example, the short-term long term memory observation is based on the observation that in tests of recall, stroke patients with impaired short term memory (regardless of method) and those using the varied examples method performed better after 24h+ than those using blocked practice with functional working memory. The hypothesis being that the constructs active in long term recall are more exercised using the varied examples method, leading to better long term performance. Another hypothesis is that increasing the complexity by interleaving examples increases the challenge level and hence engagement and motivational/reward circuits parts of the brain important for learning. In addition, interleaving examples forces a more general model to be learned, encouraging generalization instead of just short term memorization.

The comparison to machine learning (they use ANNs) is: when the examples do not reflect the distribution from which they are coming from, then the learned model is less general. And in particular, when a new set of examples with different properties is trained on it interferes negatively with already learned material. In the paper they give examples of similar occurrences in rats and humans.

Finally, it is important to note that randomly interleaving examples is not useful when trying to figure something out - where short term memory is key. The observation is that contextual interference disappears for complex tasks, this is because the information requires more complex processing and integration in working memory. The ability to hold more information and more complex models in working memory correlates strongly with the ability to understand things. Interfering with this process leads to poor performance short and long term. As the material is familiarized, compressed and basic models are composed, difficulty reduces. It is here that interleaving becomes important.

The practical implications are when practicing drill exercises, rather than blocking the material according to similarity, interleave the material so a less biased model is formed and the material is more challenging to keep focus. When designing exercises break them up into the core simple, defining examples and interleave these while gradually increasing the difficulty by composing more difficult models from the simpler material and continuing to interleaving these with the simpler basis examples set.

That's quite a lot of conjecture about the mechanisms behind what is observed in the research, but how far do the research findings themselves take us? For example, I've read about how spaced repetition affects verbal and visual recall tasks, but has its effect on motor coordination been studied at all? It's a big leap to generalize from verbal and visual recall tasks to motor coordination tasks, yet here we have an article about a researcher who studies recall of telephone numbers and such, and the article blithely advises readers to apply his research results to learning a tennis stroke. That's a terrible application of science.

I could be wrong, but the article only mentions research on recall. The conclusions reported by the article match research results on recall. The article features one researcher, who happens to study recall. Now, if you think it's common sense that research on recall says little or nothing about hitting tennis balls or dancing the Viennese waltz, then how are you supposed to read the article? Science writing elides a lot for the sake of brevity and breeziness, but I have a hard time trusting that the author knew about research justifying the same conclusions in the case of tennis and dancing and decided that instead of mentioning how broadly the findings had been confirmed, he would lead his readers to believe that it's all based on one narrow path of research. (Also, I don't think it's a very good defense of science writing to say that an author didn't make a mistake in reasoning, he only encouraged his readers to do so.)

Oh, no I did not think much of the article. I had already encountered these concepts earlier. My examples are not based on the article but on research I have consumed. I pasted some links in my first post. Yes, this has been long studied for motor tasks. Actually much of the research on the matter is based on motor learning.

From what I recall, spaced repetition works best for simple motor tasks, and less well for skills of increasing complexity - say operating a traffic control tower.