Epistemic Spot Check: The Role of Deliberate Practice in the Acquisition of Expert Performance

Epistemic spot checks typically consist of references from a book, selected by my interest level, checked against either the book’s source or my own research. This one is a little different that I’m focusing on a single paragraph in a single paper. Specifically as part of a larger review I read Ericsson, Krampe, and Tesch-Römer’s 1993 paper, The Role of Deliberate Practice in the Acquisition of Expert Performance (PDF), in an attempt to gain information about how long human beings can productivity do thought work over a time period.

This paper is important because if you ask people how much thought work can be done in a day, if they have an answer and a citation at all, it will be “4 hours a day” and “Cal Newport’s Deep Work“. The Ericsson paper is in turn Newport’s source. So to the extent people’s beliefs are based on anything, they’re based on this paper.

In fact I’m not even reviewing the whole paper, just this one relevant paragraph: 

When individuals, especially children, start practicing in a given domain, the amount of practice is an hour or less per day (Bloom, 1985b). Similarly, laboratory studies of extended practice limit practice to about 1 hr for 3-5 days a week (e.g., Chase & Ericsson, 1982; Schneider & Shiffrin, 1977; Seibel, 1963). A number of training studies in real life have compared the efficiency of practice durations ranging from 1 -8 hr per day. These studies show essentially no benefit from durations exceeding 4 hr per day and reduced benefits from practice exceeding 2 hr (Welford, 1968; Woodworth & Schlosberg, 1954). Many studies of the acquisition of typing skill (Baddeley & Longman, 1978; Dvorak et al.. 1936) and other perceptual motor skills (Henshaw & Holman, 1930) indicate that the effective duration of deliberate practice may be closer to 1 hr per day. Pirolli and J. R. Anderson (1985) found no increased learning from doubling the number of training trials per session in their extended training study. The findings of these studies can be generalized to situations in which training is extended over long periods of time such as weeks, months, and years

Let’s go through each sentence in order. I’ve used each quote as a section header, with the citations underneath it in bold.

“When individuals, especially children, start practicing in a given domain, the amount of practice is an hour or less per day”

 Generalizations about talent development, Bloom (1985)

“Typically the initial lessons were given in swimming and piano for about an hour each week, while the mathematics was taught about four hours each week…In addition some learning tasks (or homework) were assigned to be practiced and perfected before the next lesson.” (p513)

“…[D]uring the week the [piano] teacher expected the child to practice about an hour a day.” with descriptions of practice but no quantification given for swimming and math (p515).

The quote seems to me to be a simplification. “Expected an hour a day” is not the same as “did practice an hour or less per day.”

“…laboratory studies of extended practice limit practice to about 1 hr for 3-5 days a week”

Skill and working memory, Chase & Ericsson (1982)

This study focused strictly on memorizing digits, which I don’t consider to be that close to thought work.

Controlled and automatic human information processing: I. Detection, search, and attention. Schneider, W., & Shiffrin, R. M. (1977)

This study had 8 people in it and was essentially an identification and reaction time trial.

Discrimination reaction time for a 1,023-alternative task, Seibel, R. (1963)

3 subjects. This was a reaction time test, not thought work. No mention of duration studying.

 

“These studies show essentially no benefit from durations exceeding 4 hr per day and reduced benefits from practice exceeding 2 hr”

Fundamentals of Skill, Welford (1968)

In a book with no page number given, I skipped this one.

Experimental Psychology, Woodworth & Schlosberg (1954)

This too is a book with no page number, but it was available online (thanks, archive.org) and I made an educated guess that the relevant chapter was “Economy in Learning and Performance”. Most of this chapter focused on recitation, which I don’t consider sufficiently relevant.

p800: “Almost any book on applied psychology will tell you that the hourly work output is higher in an eight-hour day than a ten-hour day.”(no source)

Offers this graph as demonstration that only monotonous work has diminishing returns.

Screen Shot 2019-05-16 at 9.08.22 PM.png

 

p812: An interesting army study showing that students given telegraphy training for 4 hours/day  (and spending 4 on other topics) learned as much as students studying 7 hours/day. This one seems genuinely relevant, although not enough to tell us where peak performance lies, just that four hours are better than seven. Additionally, the students weren’t loafing around for the excess three hours: they were learning other things. So this is about how long you can study a particular subject, not total learning capacity in a day.

Many studies of the acquisition of typing skill (Baddeley & Longman, 1978; Dvorak et al.. 1936) and other perceptual motor skills (Henshaw & Holman, 1930) indicate that the effective duration of deliberate practice may be closer to 1 hr per day

The Influence of Length and Frequency of Training Session on the Rate of Learning to Type, Baddeley & Longman (1978)

“Four groups of postmen were trained to type alpha-numeric code material using a conventional typewriter keyboard. Training was based on sessions lasting for one or two hours occurring once or twice per day. Learning was most efficient in the group given one session of one hour per day, and least efficient in the group trained for two 2-hour sessions. Retention was tested after one, three or nine months, and indicated a loss in speed of about 30%. Again the group trained for two daily sessions of two hours performed most poorly.It is suggested that where operationally feasible, keyboard training should be distributed over time rather than massed”

 

Typewriting behavior; psychology applied to teaching and learning typewriting, Dvorak et al (1936)

Inaccessible book.

The Role of Practice in Fact Retrieval, Pirolli & Anderson (1985)

“We found that fact retrieval speeds up as a power function of days of practice but that the number of daily repetitions beyond four produced little or no impact on reaction time”

Conclusion

Many of the studies were criminally small, and typically focused on singular, monotonous tasks like responding to patterns of light or memorizing digits.  The precision of these studies is greatly exaggerated. There’s no reason to believe Ericsson, Krampe, and Tesch-Römer’s conclusion that the correct number of hours for deliberate practice is 3.5, much less the commonly repeated factoid that humans can do good work for 4 hours/day.

 

[This post supported by Patreon].

Kencko Fruit Powder: Better Than Anything I’m Actually Going to do

Sometimes the modern economy really delivers.

As longtime readers know, I have two strikes against me when it comes to food: it requires both chewing and digesting. Chewing is painful for me due to nerve damage in my jaw. Digesting… well some of the problems with digestion are caused by insufficient stomach acid, but those are easily treated with a pill. I still have problems when I take the pills and no one knows why. So I eat a lot of things that require minimal chewing and are easy to digest. This set of things has very little overlap with the set of things my nutritionist wants me to eat, such as produce. I eat some fruits and veggies, especially in the summer, but not nearly enough.

Enter Kencko.

 

 

Kencko produces small packets of powderized fruits and vegetables. This requires no chewing and substantially less digestion. They taste fine. Not amazing, but fine. You could probably make them taste better by adding sugar or honey. Because they’re produced by freeze drying, they’re better nutritionally than other preserved fruit. Not as good as fresh, but, in the words of my nutritionist, “better than anything you’re actually going to do.” 

Nutritionists are hit-or-miss, so I double checked the nutrition claim myself. Based on a rushed review (primary source), I find that freeze drying has some nutritional loss, exact amount depending on the nutrient, but within the range that could conceivably counterbalanced by the increased digestibility of powder (this also means the sugar hits faster), and also the fact that I’m eating them at all. I suspect the biggest loss is the absence of probiotic flora in the sterilized powder packets.

There’s the issue of price. I was originally going to apologize for the price, chalk it up to convenience, and plead necessity for myself, but it turns out the packets are not that expensive relative to comparables. Ordered in the largest size, Kencko is $3.07/ounce. I spent 45 minutes finding prices for other freeze dried fruit powders, and that’s as good as you can do short of wholesale (spreadsheet). There are cheaper powders, but they’re inevitably something other than freeze-dried.

How about compared to actual fruit? It takes .44 lbs of fruit to produce one 20 g Kencko packet (price: $2.16-$3.30, depending on quantity ordered). According to this USDA report (chart on page 3), .5 lbs is $0.66-$0.90 cents worth of apples, $2.16 worth of blueberries, or $2.10-$2.85 worth of cherries. Note that those are advertised prices, so probably less than what you’d pay on average and certainly less than what you’d pay out of season, and for conventional produce rather than the organics Kencko uses. Kencko is definitely more expensive than in-season, on-sale produce, but not ridiculously so. Plus it never goes bad so you’re not paying for produce you throw away.

The worst thing I will say about Kencko is that their mixer bottle sucks. It mixes less well and is harder to clean than a Blender Bottle (affiliate link), buy one of those or use a spoon.

Obviously if you can just eat a vegetable you should do that. But if you find that untenable for some reason, Kencko is a reasonable way to turn money into consumed produce. This is an incredibly good trade for me and I’m really happy it exists.

[Kencko has not paid me for this post and I’m not in contact with them beyond ordering the product and following them on Twitter.]