# The Comprehension Curve

**Tl;Dr:** You might comprehend and learn more quickly by *slowing down* your reading, rather than by *speeding it up.* This post is mainly about laying down some terminology that I think is conceptually clarifying in thinking about learning, comprehension and reading speed.

**Speed Reading**

According to Google Trends, interest in speed reading has been on a pretty steady decline since 2004. It briefly became more popular in March 2014, perhaps due to an [Atlantic article](https://www.theatlantic.com/health/archive/2014/03/is-speed-reading-possible/284326/) published that month, on the speed reading app Spritz.

![](https://39669.cdn.cke-cs.com/rQvD3VnunXZu34m86e5f/images/282a6ffbd1f2eb15767786fa6b5a2c611e8ed2b53923581b.JPG)

Nevertheless, when a person starts thinking about "learning how to learn," speed reading is one of the natural things to investigate. Am I reading fast enough? What's the maximum possible words per minute at which I could still comprehend the material? Couldn't I compensate for low comprehension just by reading much, much faster? So they Google "speed reading," and resurrect the conversation.

The fundamental idea of speed reading is that by reducing wasted motion in the physical eye movements involved in reading, people can dramatically increase the number of words per minute (WPM) that they can read, without sacrificing comprehension. Speed reading advocates point to evidence that speed readers show no statistically significant difference from normal readers in performance on comprehension tests. For such research to be meaningful, it needs to be executed with care. This care is generally lacking, as I describe below.

Speed reading is most obviously helpful under a narrow set of conditions:

1.  The document you have to read is your only source of the information.
2.  The information it contains is easy for you to comprehend.
3.  You still need to read the document for some reason.

Real-world examples might include a lawyer reading boilerplate, a teacher reading the essays of young students, or a businessperson reading memos. Another might be a student who wants to honestly be able to say they read the Scarlet Letter, but who doesn't care about the book very much and plans to study for the test using CliffNotes.

One of the nice things about reading speed is that it's easy to quantify. You can paste text into an app like [Spreeder](https://www.spreeder.com/app.php) and set the speed as fast as you'd like to go.

But if you primarily want to *comprehend quickly*, rather than merely *read quickly*, then it's not fundamentally your reading speed, but your comprehension rate, that you want to maximize.

**The Comprehension Curve**

Unfortunately, comprehension is hard to quantify. Despite this challenge, we can think about its relationship with reading speed conceptually in terms of the Comprehension Curve.

![](https://39669.cdn.cke-cs.com/rQvD3VnunXZu34m86e5f/images/4c45ef8d386022d1fe5107494d276cf9b5f0a9c26530aea1.png)

The Comprehension Curve is analogous to the [Laffer Curve](https://en.wikipedia.org/wiki/Laffer_curve). Briefly, the concept of the Laffer curve is that if the government taxes at 0% or 100%, it will receive no revenue, either because it will take none of people's money, or because nobody will be willing to work. Thus, the ideal rate of taxation to maximize revenue is somewhere in between. If the current tax rate is higher than the ideal tax rate, the government could in principle cut taxes while increasing tax revenue.

The point of the Comprehension Curve is that each person, for a certain text at a certain time, has an ideal *reading* speed  that maximizes their *comprehension* rate. If a person was reading faster than their ideal reading speed, they could comprehend more quickly by reading more slowly. Of course, it's hard to know whether an individual is reading faster, slower, or right at their ideal rate, just as it's hard to determine the ideal tax rate to maximize tax revenue. However, we can make some plausible assumptions, given below, to help us think about this problem in more depth.

The vertical axis on the Comprehension Curve needs some unpacking. "Comprehension rate" has four important pieces of nuance:

1.  It refers to **comprehension**, not learning in general. Comprehension is hard to define, but think of it as that first step in importing words from the page (or from an oral speech, a picture, graph, or sensation) into your mind. It's that form of learning that you can achieve at the same time as you read/listen/pay attention. By contrast, learning can also refer to long-term retention, ability to apply a concept to solve a problem, physical technique gained through practice, and real-world experience. Comprehension is just the first step in learning from a text, presentation, or demonstration, or other similar experience, where the material is transduced from the page into the mind.
2.  It refers to the **rate** of comprehension, not an amount. A student at the start of their study session has comprehended only a small amount, but may be comprehending at a fast rate.
3.  Comprehension rate is **personal and contextual**, not with reference to some human average or theoretical limit. Comprehension rate is specific to a particular text, reader, environment, level of background knowledge, and level of reading skill.

The Comprehension Curve lets us see that "speed reading" starts with the assumption that most people, most of the time, are on the left side of the Comprehension Curve. If true, then they could increase their rate of comprehension by reading faster.

But the **personal and contextual** nature of reading suggests that in many cases, this is not a plausible assumption. If a person hears that the average reader has a 250 WPM reading speed, and that skilled speed readers can go 1,000 WPM, then tries to paste a dense biology textbook into a speed-reading app, they might run into problems.

Compounding this practical problem, some speed reading advocates suggest to novices that they should continue practicing speed reading, *despite* their (initial) lack of comprehension. For example, an article on MindTools.com states:

"You will probably find that you retain very little information at first, but, as you train your brain and you become more comfortable with the technique, your comprehension should improve."

It's OK to accept a temporary setback in order to train in a more powerful method. For example, a pianist who learned poor technique as a child might temporarily play worse as they work to master a better technique. But this is only a useful tradeoff if the technique  is indeed more powerful once mastered.

If people who are trying to comprehend at a faster rate turn out to be in the middle or on the right side of the Comprehension Curve, then even mastery of speed reading will harm their comprehension. Even if they're on the left-hand side, if they overshoot their ideal reading speed, their comprehension rate will suffer.

Training people to accept and ignore a harm, under the assumption that it's a temporary harm, is a dangerous, if sometimes necessary, message.

**The Natural Pace Hypothesis And The Difficulty With Comprehension Tests**

Does it seem plausible that we could dramatically increase our reading speed from our natural pace and attain a higher comprehension rate? After all, don't people naturally find a pace that optimal for their own brain and needs? Let's call this the "natural pace hypothesis."

If we accept the natural pace hypothesis, then it's an unlikely hypothesis that altering a person's reading speed could improve their comprehension, or whatever other outcome they're optimizing for. We therefore need a lot of strong evidence to make us accept it.

Alternatively, it might be more plausible to assume that people habitually read at a fixed rate, regardless of the subject matter or their level of familiarity. Perhaps they always read at a pace of 250 words per minute, no matter whether they're reading a novel, an Ikea manual, or a math proof, out of sheer habit. If so, they might benefit by calibrating their reading speed to the specific text, but it's not clear that speeding up their reading is generally the right move on the Comprehension Curve.

A third possibility, though, is that people read at a pace that they learned as children. As experienced readers, they can dramatically increase their reading speed, yet remain generally stuck at that deeply ingrained, childhood pace. For that reason, we can assume that most people, most of the time, have an ideal reading speed that's faster than their habitual one. If so, that would make speed reading seem like a more plausibly useful general intervention.

One way that speed reading advocates claim to test the hypothesis that speed reading does not interfere with comprehension is by administering comprehension tests to speed readers and normal readers, and comparing the results. If the speed readers do at least as well as the normal readers, then speed reading hasn't harmed their comprehension. Even if speed reader comprehension is worse than that of normal readers, it may be made up for by the sheer amount they're able to take in.

Rayner, et al provide an [excellent review](https://journals.sagepub.com/doi/full/10.1177/1529100615623267) both of the technique of speed reading and the flaws in many of these comprehension tests.

In addition to looking at real research, it's useful to think of what an ideal study, and interpretation of the evidence it provides, would look like.

"Speed reading" can be defined across three orders of magnitude. If the average pace is 250 WPM, is "speed reading" 500 WPM? 2,500 WPM? [25,000 WPM](https://ntrs.nasa.gov/citations/20000011599)? When we have study results, we shouldn't extrapolate too much from them to other types of texts, learners, or reading speeds. For that reason, claims that "studies show speed reading \[does/does not\] work" should be treated with skepticism.

But more importantly, what do we make of it when a study shows that we find no significant difference between speed readers and normal readers, for a given technique, text, and reading speed?

We could interpret this in two ways:

1.  The studied approach to speed reading allows faster reading with no loss of comprehension. Speed reading works!
2.  The comprehension test was too hard, or it wasn't hard enough.

As an example of a too-easy test, imagine that the text is a children's book, and the questions are asking about the basics of character and plot. If this test is given to proficient adult readers, they might be able to pick everything up based on a quick scan.

An example of a too-hard test would be having a group of chemistry students read a passage on the derivation of the [Michaelis-Menten equation](https://en.wikipedia.org/wiki/Michaelis%E2%80%93Menten_kinetics). If the comprehension test questions ask them to extend and apply that equation to difficult word problems, it may be that both of them would have such a hard time that neither group was able to answer the questions correctly.

To do a good comprehension test, you'd need to find a good operationalization for "normal" and "speed" reading. Perhaps you could establish a "normal range" of reading speeds by asking a group of subjects to read the text once, at their own speed, and to then determine the interquartile range - the range between the top 75% and bottom 25% of reading speeds.

Then you'd establish a corpus of texts that all reliably produce the same "normal range," and test to see whether or not individual people tend to read all texts from this corpus at around the same speed.

Once you had a corpus of such texts, you might expose speed readers to them, presenting some texts at "normal range" speeds, and others at the speed reading rate you're testing. If the speed reading rate produced significantly different comprehension than the normal rate, this would be evidence of whether or not speed reading would be beneficial for most people, *at that speed* and *for similar texts.*

**From "Speed Reading" To "Eye Technique" and "Mental Technique"**

If you read the Rayner review, you'll notice that speed reading technique partially focuses on refining one's physical eye movements.

*   Fixations: how often and how long the eyes fix in place.
*   Saccades: how far the eyes move between fixations.
*   Regressions: how often the eye travels to an earlier point in the text.

What if we referred to the collection of techniques meant to optimize these motions not as "speed reading" but as "eye technique?"

After all, if these techniques represent improved eye technique, this improvement need not be in terms of reading speed. It could be, for example, that a reader with excellent eye technique reads at exactly the same speed as the average population, yet has improved comprehension nonetheless. Perhaps their more carefully coordinated eye motions enhance the visual clarity of the text itself, or otherwise help the reader identify and focus on the most important words.

So it may be that the eye techniques that are normally referred to as "speed reading" are useful to learn, even if the "natural pace hypothesis" is correct and most people read at their ideal reading speed.

Another way of stating this is that advocates and detractors of "speed reading" tend to conflate two hypotheses:

1.  Practice with a particular set of eye techniques can be useful to readers.
2.  Rate of comprehension is bottlenecked by words read per minute.

Even if reading speed is not the bottleneck to faster comprehension rates for most people, better eye technique might still be helpful for other reasons.

Beyond "eye technique,"  Abram Demski points out in the comments that speed readers also focus on bypassing the inner monologue when reading. They encourage readers to avoiding hearing the words on the page in their head, and instead to practice translating words on the page directly into concepts in the mind. We can call this a form of "mental technique."

The theory behind this particular mental technique is that it avoids the delay of translating text into inner speech, and inner speech into concepts. This is plausible, but there could be other forms of mental technique, with other compelling justifications. No matter which mental technique is chosen, it need not be put to use to increase reading speed. It could probably also be used at normal reading speed in order perhaps to improve comprehension rate.

In the case of this "audio cortex bypass" mental technique, it could be that the bypass helps people engage other, more useful faculties of mind for supporting comprehension. Perhaps if people don't hear the *word* "normal distribution" when they read it in a statistics textbook, they'll instead *visualize* a normal distribution, which would give them genuinely useful information to work with that hearing the words simply does not.

However, it might also turn out that "audio cortex bypass" enhances reading speed, but harms comprehension, either through moving the reader too far to the right on the Comprehension Curve, or by interfering with a useful faculty of mind for comprehension. I have anecdotally found that engaging my audio cortex in a particular way dramatically enhances my comprehension, which I will describe in more detail in a future post.

This is mere anecdote. But the real problem here is that speed reading advocates assume that "audio cortex bypass" is the right way to go, and scientists dutifully test it. Neither of them seem to step back and reconsider how we might plausibly improve comprehension rates through improved reading techniques, be they eye techniques, mental techniques, or some other technique entirely.

**Where's The Comprehension Bottleneck?**

Thinking in terms of a "comprehension bottleneck" can point to what we really want to know. Is the average person's *natural* approach to reading for comprehension - their eye technique, speed, cognitive reflection - their *ideal* approach as well? In other words, can the rate of comprehension be improved through better technique? And if so, what is the limiting factor, or bottleneck? If we aren't achieving our personal maximum comprehension rate, what aspect of poor technique is holding us back?

A multi-step chemical reaction can only proceed at the rate of its slowest component reaction. It also has a theoretical maximum, determined by the rate of diffusion. Likewise, comprehension can only proceed at the rate of the slowest component technique: health-promotion and focusing technique, material-selection technique, environment-setup technique, eye technique, mental technique, attention-maintaining technique. It also has a theoretical maximum for an individual, determined by the physiology of their brain.

![](https://39669.cdn.cke-cs.com/rQvD3VnunXZu34m86e5f/images/1dfb8b86aa1cfcf20005935bcc2438e3d19214edf714c725.png)

Again, what I refer to above as *mental technique* is the set of voluntary thought-behaviors that that are under conscious control: our ability to visualize and activate our sensory imagination, our inner monologue, our memory.

An individual interested in experimenting with finding and improving the technique that is their comprehension bottleneck might best approach this by having a rich set of techniques with which to experiment.

Some techniques are addressed by specialists, such as psychiatrists who can prescribe medication for ADHD. Other professional specialties that seem like they would be useful are deeply unconventional. How often does a professional researcher consult with a reading teacher to see if their technique can be improved? By contrast, even highly accomplished musicians continue to work with music teachers throughout their career.

What book or professional would a "professional reader" - a lawyer, journalist, scientist, anybody in a knowledge profession - turn to in order to assess and improve the broad range of techniques that factor into their comprehension bottleneck? The problem is fractured into bits, each dealt with either by a different professional or with no expert attention at all.

Finally, it seems valuable to contextualize comprehension as one possible learning bottleneck. A person might, for example, achieve a very fast rate of comprehension when they read a textbook, yet fail to remember almost any of it a year later. If their goal is long-term retention, then improving their rate of comprehension is not the bottleneck for their learning.

Yet there could be a relationship between these facets of learning. For example, a faster rate of comprehension would mean that a student could devote more time to reviewing previously-learned concepts, which might improve long-term retention. Likewise, better comprehension might improve performance on applied work, such as labs or problem sets, or improve motivation. Being able to think clearly about the difference and relationship between comprehension and learning, and to view learning as a decomposable set of processes, akin to chemical reactions, each with a technical limiting factor and theoretical maximum rate, seems like the correct approach.

In this state of insufficiency, the goal of this article is to bring some conceptual clarity to the subject of reading speed and comprehension. The most important concepts are the "comprehension rate," the Comprehension Curve, the comprehension and learning bottlenecks, and the revisionist concept of "eye technique" and "mental technique" as part of a set of linked reading comprehension techniques.

*Thanks especially to Abram Demski for thoughtful comments.*