Ian Leslie’s “Curious”: Book Review, Notes + Analysis

Poor Ash’s Almanack > Book Reviews > Effective Thinking > Psychology

Overall Rating: ★★★★★ (5/7) (solid for its category)

Per-Hour Learning Potential / Utility: ★★★★★ (5/7)

Readability: ★★★★★★ (6/7)

Challenge Level: 1/5 (None) | 190 pages ex-notes (256 official)

Blurb/Description: What is curiosity, why does it matter, and how can we cultivate it?

Summary: This is a hard book to summarize in the sense that it’s a bit all over the place.  The premise:

Pure curiosity is unique to human beings... It’s only people, as far as we know, who look up at the stars and wonder what they are. - John Lloyd via Ian Leslie Click To Tweet

The book contains some psychology, some sociology, some evolutionary biology, some history – parts of it are extremely interesting and useful.

Highlights: The bit about babies on page 25 is actually hugely insightful.  Leslie (pictured at right) presents a lot of valuable information and thoughts, especially in the first half of the book.

Lowlights: Leslie’s implicit argument that all knowledge is equally valuable (it’s not), and his well-intentioned but (very) misguided sort-of defense of memorization-based education.  Also, the second half of the book drops off rapidly in terms of utility, especially toward the end – it is sort of interesting but not useful.  

Mental Model / ART Thinking Points: status quo bias, novelty-seeking, trait adaptivitynonlinearityutilityempathyconfirmation biasoverconfidenceprobabilistic thinkingculturememory,opportunity coststructural problem solving

You should buy a copy of Curious if: you want an interesting exploration of a topic that isn’t discussed nearly as much as it should be.

Reading Tips: Focus more on the first half of the book and skim the back half.  Don’t take Leslie’s natterings about memorization and celebration of “useless’ knowledge seriously.

Pairs Well With:

The Seven Sins of Memory by Daniel Schacter ( 7SOM review + notes) or  The Design of Everyday Things by Don Norman ( DOET review + notes).  Great rebuttals to Leslie’s brutally misguided defense of memorization-based education: if things mean anything, we don’t need to memorize them.

The Genius of Birds by Jennifer Ackerman ( Bird review + notes).  It turns out that some birds display behavior that is (sort of) curious – which is sometimes  adaptive, sometimes not.  A lovely book.

Other Minds by Peter Godfrey-Smith ( OthM review + notes).  A wonderful exploration of octopuscognition – it turns out octopi are curious, too!

Reread Value: 2/5 (Low)

More Detailed Notes + Analysis (SPOILERS BELOW):

IMPORTANT: the below commentary DOES NOT SUBSTITUTE for READING THE BOOK.  Full stop. This commentary is NOT a comprehensive summary of the lessons of the book, or intended to be comprehensive.  It was primarily created for my own personal reference.

Much of the below will be utterly incomprehensible if you have not read the book, or if you do not have the book on hand to reference.  Even if it was comprehensive, you would be depriving yourself of the vast majority of the learning opportunity by only reading the “Cliff Notes.”  Do so at your own peril.

I provide these notes and analysis for five use cases.  First, they may help you decide which books you should put on your shelf, based on a quick review of some of the ideas discussed.  

Second, as I discuss in the memory mental model, time-delayed re-encoding strengthens memory, and notes can also serve as a “cue” to enhance recall.  However, taking notes is a time consuming process that many busy students and professionals opt out of, so hopefully these notes can serve as a starting point to which you can append your own thoughts, marginalia, insights, etc.

Third, perhaps most importantly of all, I contextualize authors’ points with points from other books that either serve to strengthen, or weaken, the arguments made.  I also point out how specific examples tie in to specific mental models, which you are encouraged to read, thereby enriching your understanding and accelerating your learning.  Combining two and three, I recommend that you read these notes while the book’s still fresh in your mind – after a few days, perhaps.

Fourth, they will hopefully serve as a “discovery mechanism” for further related reading.

Fifth and finally, they will hopefully serve as an index for you to return to at a future point in time, to identify sections of the book worth rereading to help you better address current challenges and opportunities in your life – or to reinterpret and reimagine elements of the book in a light you didn’t see previously because you weren’t familiar with all the other models or books discussed in the third use case.

The premise of Ian Leslie’s Curious, via British television producer John Lloyd in his pitch of the “QI” program to the BBC:

“ever since Darwin, we have had to come to terms with the fact that we share with our primate cousins the same three basic drives: food, sex, and shelter.  But humans possess something else: a fourth drive. ‘Pure curiosity,’ said Lloyd, ‘is unique to human beings.

When animals snuffle around in bushes, it’s because they’re looking for the three other things.  It’s only people, as far as we know, who look up at the stars and wonder what they are.’”

It’s not 100% clear to me that this is true, at least in the sense that to the extent that curiosity is related to sensation-seeking or novelty-seeking, other species can engage in it as well.  Jennifer Ackerman’s The Genius of Birds (Bird review + notes) and Peter Godfrey-Smith’s “ Other Minds (OthM review + notes) both describe behavior in birds and octopi (octopuses), respectively, that looks a lot like curiosity to me.

Anyway.  Curiosity, per Leslie:

assumes all rules are provisional, subject to the laceration of a smart question nobody has yet thought to ask.”  

In other words, it’s sort of the negation of status quo bias.  Leslie echoes the Thiel-ian view that we’re in a stagnation period without major innovation besides the Internet.

Leslie provides a scale for measuring “need for cognition,” a measure of curiosity – (I’m probably a medium score, insofar as I really enjoy thinking and cognition but at least at this point in my life, have little tolerance for things that are interesting but not useful).  Leslie differentiates between simply seeking out information and “effortful” deeper inquiry.

I do think it’s worth noting here that need for cognition is adaptive in a manner that’s dose-dependent.  What do I mean by that?  As I explore in the  nonlinearity model, many people with a high “need for cognition” and desire for intellectual stimulation are drawn to investing as a career, and some of this is definitely necessary and valuable.

Too much, however, can be bad: a lot of investors fall down the trap of solving hard problems for the sake of solving hard problems – jumping over ten-foot hurdles when there are half-foot ones nearby – when there’s no  utility in doing so.  As Buffett/Munger would put it,

“There are no points for difficulty.”

So, something to think about.

Leslie also differentiates between simple “diversive” curiosity – attraction to everything novel (the phenomenon Buzzfeed/Twitter plays off) – vs. deeper “epistemic” curiosity, a “quest for knowledge and understanding.”  

He also mentions  empathic” curiosity – a “genuine” attempt to put yourself in someone else’s shoes. (See the empathy model.)  He argues that DC has always been with us, while the two ECs (I’ll call them EpC and EmC for short) started flourishing only post the printing press and Industrial Revolution.  If nothing else, curiosity seems to drive better mental performance as you age – a 2013 Chicago study found that lifelong readers slowed mental decline by one-third (explains how Munger’s so sharp at 92, I guess!)

Diversive curiosity isn’t just distracting, but can also be dangerous (Leslie cites incidents of children playing with guns they find).  Epistemic curiosity is interesting (an example of homo sapiens “misbehaving” – see Thaler’s Misbehaving – M review + notes – because, as Leslie puts it:

we take risks to achieve knowledge that has no immediate use or benefit… economists find this hard to explain…

it’s also hard to understand from an evolutionary standpoint.”  

would also question this based on my understanding of trait adaptivity.  Going back to Ackerman’s The Genius of Birds (Bird review + notes) – she consistently references the  tradeoff between fear (margin of safety) and bravery (which can lead to novelty-seeking).  For example, she mentions that it tends to be the braver, more fearless sparrows that push the boundaries of their territory… as she explores, sparrows now rule the world.

So, from an evolutionary biology perspective, I think it’s perfectly possible that our desire to seek out information evolved because it was generally adaptive, and one of the side effects – “epiphenomena,” as Dr. Matthew Walker describes the heat of lightbulbs in Why We Sleep (Sleep review + notes) – is that we occasionally acquire information that isn’t  useful.

So anyway.  Leslie continues with a hypothesis that our brains evolved to give us the capacity to make “speculative investments” in knowledge that might or might not pay off – but more information in general was good, especially if we traveled through unfamiliar territory.

There’s also a good quote on culture:

Culture freed humans from the limitations of biology… we became the only species to acquire guidance on how to live from the accumulated knowledge of our ancestors, rather than just from their DNA. - Mark Pagel via Ian Leslie Click To Tweet

Again, not sure this is totally true – Ackerman notes in The Genius of Birds (Bird review + notes) that there is some evidence on the presence of culture in birds – but it’s a reasonable enough premise, directionally.  See Laurence Gonzales’s Deep Survival (DpSv review + notes), among other books, that examine how powerful our culture is… and just how helpless we are without it.

Leslie cites the evolutionary biology theory as commonly understood: that our extended period of infancy/adolescence relative to other species allows us to learn and acquire culture.  There’s also a mention of a study I don’t think I’ve seen before – curious babies are more likely to go on to academic success.  Leslie characterizes curiosity development as a composite of innate cognitive intelligence and encouragement from parents (i.e. responses to pointing, questions, etc).

I don’t know where to stick this quote from page 25, but I always find it hilarious:

 “babies [who were told a cup is a shoe] were much less likely to engage in pointing…

it is sobering to think that even at an early age, infants are capable of telling whether or not you’re an idiot – a judgment that, when you think about it, demands substantial cognitive and social abilities.”  

Leslie goes on to cite research by psychologist Michelle Chouinard that found children posed “more than a hundred questions every hour” – two thirds of which were “designed to elicit information” – thus, Chouinard concludes question-asking “is a central part of what it means to be a child.”

At about age three, kids start asking how and why questions versus what and where questions (and these “explanatory” questions get asked 25x/hour).  

We get less curious as we age because we’ve accumulated more knowledge and our brains get more set neurologically – adults tend to err more toward “exploitation” of existing knowledge rather than “exploration” (i.e. adding to it) per Leslie.

Leslie delves into an explanation of the circumstances under which we experience curiosity – one promising theory is the “information gap,” i.e we are curious when something is a “medium” surprise but not a low or high one – lows aren’t worth investigating; highs are uninteresting (like opera details if you know nothing about opera).  He notes, on confirmation bias, search satisficing, overconfidence, and non- probabilistic thinking:

When people assume they have the answers, they become blithely uncurious about alternatives. - Ian Leslie Click To Tweet

See also pages 169 – 170 of Groopman’s “ How Doctors Think ( HDT review + notes), which talk about doctors’ tendency to do this; Groopman’s whole book explores how doctors often underestimate  multicausality 

Anyway, regarding knowledge, what Leslie says is certainly true in my experience – I’m not sure I’d dimensionalize it using “surprise,” but my desire to know more is usually strongest in fields where I have enough knowledge to be conversational, but I know I’m lacking in depth.  

At a certain point, it levels off (i.e. I have little curiosity about learning more deeply about specific portions of finance, for instance,) and at the opposite end, I do find it hard to break into totally new fields (because I usually have no idea where to start).  

For our purposes, an interesting practical application of this is that “survey” books like “The Lessons of History” (LessH review + notes) can actually be super useful in, at least, getting you over that initial hump and providing a jumping-off point for further research or giving you a “hook” into the topic.

Leslie also notes that “curiosity is underwritten by love” – an example of a bottleneck – when you’re anxious or insecure, you don’t have the cognitive resources to be curious.

Again, see Ackerman’s “ The Genius of Birds – Bird review + notes – where she explores how many of the highly intelligent birds, like crows, had circumstances that made them at less threat from predators.  Talking about one of the most intelligent bird species in the world, Ackerman notes on pages 76 – 77 of GoB, for example, that thanks to their island paradise with no natural predators:

 “[New Caledonian] crows are free from the burden of vigilance – in other words, they have the time and ease of mind to tinker with sticks and barbed leaves […] without looking up.”

Ackerman also explores, in the book, how the quality of birds’ songs may be linked to their early-life nutrition; birds that faced privation during their early days in the nest might be less able to learn their songs and sing them as well.

Per Leslie, curiosity also plays into good storytelling; he notes that skillful presenters manipulate the “information gap” to keep audiences hooked.   

This is definitely true: a lot of well-written nonfiction books, like Gregory Zuckerman’s The Frackers (Frk review + notes), Charles Duhigg’s The Power of Habit (PoH review + notes), or Brad Stone’s The Upstarts (TUS review + notes), tend to use an A/B storytelling style where they are weaving multiple threads at once, such that you have to keep turning the pages to conclude not just one, but all of them…

Per Leslie, the difference between “puzzles” vs. “mysteries” is that they are “what” vs. “why” questions – puzzles are more contained; mysteries are more unbounded, and continue to be fascinating for longer (vs. a cop show no longer being interesting once the perp is caught).  

Leslie, several times, makes the point that we better remember things which are more difficult to learn (for the underlying psychological mechanisms, Schacter’s “Seven Sins of Memory” –7SOM review + notes – which goes into some depth on elaboration and encoding.)  

Leslie seems to be directionally negative on technology – while he calls Wikipedia an “amazing tool,” he also seems to have some nostalgia for the fact that it used to be harder to find information – here and elsewhere, I think he’s focused more on the downside than on the positives – for example, me and all my friends constantly go down wikipedia rabbit holes (and this is not a unique experience, google it.)  He does eventually (pg 72) call the Internet the “best-ever resource for the curious mind.”

There’s a cute quip at the bottom of page 60 about Twitter – Saint Augustine wrote “of being distracted from his prayers by his curiosity about a passing lizard or a spider catching flies (luckily for him, he never had to cope with Twitter.)”  Cal Newport would dig (see “ Deep Work” – DpWk review + notes – for an antidote to the distraction era.)  Leslie references the Renaissance – cross-reference Greenblatt’s Swerve here for more details…

One of Leslie’s stronger points is the discussion of how stories stimulate our “empathic curiosity” – I’m a bit biased (being fond of both reading and writing fiction), but I think this is something that’s often overlooked, although it has to be literary rather than plot-driven to be of value.

Leslie also discusses the idea of serendipity and the “winner-takes-all” dynamics of curiosity in the age of the Internet – what he terms “cognitive polarization” – he quotes a Redditor at the top of page 84, answering a posed question about what would be hardest to explain to someone from the 1950s:

I possess a device, in my pocket, that is capable of accessing the entirety of information known to man. I use it to look at pictures of cats and get into arguments with strangers. - a Reddit user, via Ian Leslie Click To Tweet

Leslie posits that education levels are positively correlated with curiosity at both the parental and child level.  There may be a feedback mechanism here as a prerequisite for some of these sorts of curiosity is intelligence, and the research notes that education is one of the few things that can reliably boost IQ – see Stuart Ritchie’s “intelligence” ( Intel review + notes) for more here.

Separately (and usefully), Leslie proposes a “you idiot” test – when you’re asking a question, if you could append “you idiot” to the end, don’t ask – you’re not actually being curious, just a self-promoting jerk…

There is an interesting anecdote of Sugata Mitra on pgs 105 – 108 – I haven’t watched the Ted Talk yet but need to at some point – basically, he left computers in the middle of third world India, and kids learned to use them…

At this point, Leslie transitions into a well-intentioned but brutally misguided (and, in my view, entirely incorrect) defense of memorization-based education paradigms.  

As a caveat here, he doesn’t really wholly specify what his own point of view is – or exactly what the “progressives” he’s in disagreement with are promoting – so I could be going down a rabbit hole.  

Nonetheless, Leslie makes the rather sensible point that given that memory is associative, you do need to have some facts and figures in your head to even be curious enough to learn.

But it’s a GIANT leap from there to the idea that memorization should be incentivized in education.  First of all, this is a worry that has existed (and been disproven) for millennia; see an excellent takedown of this line of thinking on pages 285 – 288 of Don Norman’s god-level The Design of Everyday Things (DOET review + notes).  As Norman notes there:

“Socrates complained about the impact of books, arguing that reliance on written material would diminish not only memory but the very need to think, to debate, to learn through discussion […] but over the years […] human intelligence has certainly not diminished […] does the fact that I can no longer remember my own phone number indicate my growing feebleness?  

No, on the contrary, it unleashes the mind from the petty tyranny of tending to the trivial and allows it to concentrate on the important and the critical. […] the power of the unaided mind is highly overrated.

[…] Human intelligence is highly flexible and adaptive, superb at inventing procedures and objects that overcome its own limits. The real powers come from designing external aids that enhance cognitive abilities.”

And, I mean, this is the exact point of cultureStructural problem solving.  Reductio ad absurdum, Leslie’s arguing that we should rely on our brute strength to build houses rather than using power tools and prefabricated parts from machines.  Our culture has effectively outsourced our memory.  (I make similar arguments about The Knowledge vs. GPS in the trait adaptivity mental model, in the memory interaction.)

Second, let me use an analogy from my undergraduate education in biochemistry.  A typical test question in a bio class looked something like this:

Which enzyme catalyzes the transformation of succinyl-CoA to succinate in the citric acid cycle?

  1. succinyl-coA synthetase
  2. Succinyl dehydrogenase
  3. Succinate synthetase
  4. Succinate dehydrogenase
  5. Succinylase

This calls to mind Richard Feynman’s classic discussion of the name of a bird  – “when you know all the names of that bird in every language, you know nothing about the bird… names don’t constitute knowledge.” Utility.

It is quite possible that my professors tried to teach us about more important things, but, remembering the power of incentives, if all you test for is names and dates and other such nonsense, that’s all your students are going to remember.  Full stop.

Indeed, through my own autodidactic adult learning, I have not found rote memorization to be usefulwhatsoever in any way.  For example, I encountered the Robinson-Patman Act in Marc Levinson’s The Great A&P and have no clue which year it was passed (sometime in the 1930s, I think) and it doesn’t matter… much more interesting is the why (“you either die a hero or live long enough to see yourself become the villain”) and the what was the impact … in fact, I don’t even really need to know that it was called the Robinson-Patman Act; just generally knowing “there was a law that made price discrimination illegal” would be a sufficient-enough approximation.

Moreover, when reading the Seven Sins of Memory, does it matter who did which study at whichuniversity?  Not unless I’m going to go deeply contextualize that (to figure out potential political pressures, history of their research – etc) – and let’s face it, I’m not.  In fact, unless an individual study is particularly relevant, that’s not even important… it’s more important just to remember the takeaway: i.e. that memory works on an associative basis – or so on.

The problem with Leslie’s argument is that it runs counter to my experience as a highly driven student – memorization-based education not only sapped my desire to learn and my interest in any given topic, but it also literally inhibited me from learning.  You hear this from a lot of smart people, ranging from modern entrepreneurs to historical luminaries like Charles Darwin.  Darwin, in his own words, from “ The Autobiography of Charles Darwin ( ABCD review + notes):

“nothing could have been worse for the development of my mind than Dr. Butler’s school, as it was strictly classical… much attention was paid to learning by heart the lessons of the previous day…

but this exercise was utterly useless, for every verse was forgotten in forty-eight hours.”  

Darwin, of course, was never considered a great student, and he went on to be one of the most influential scientists in history.

In areas like history or biology, for example, it wasn’t until I started studying them on my own (and focusing much more on the WHYs and HOWs than the WHOs and WHENs and WHEREs) that I learned anything interesting or useful. 

Ordinary Men” (OrdM review + notes) or Swerve are great examples within the field of history – it sure isn’t the date or person that’s important, but rather the why.  Ultimately, I wonder if much of the memorization paradigm is driven more by a human desire for immortality – a fear that if we don’t remember who did whatwhen, we ourselves will be forgotten by the future…

Finally, given the data presented in 7SOM – i.e., that to memorize something, you really have to dwell on it and pay attention and repeat it over time – there’s a huge opportunity cost to memorization even on the non- incentives layer – i.e., that you’re wasting time memorizing dates and names rather than critically analyzing the more important stuff.

So, memorization is dumb.  Don’t do it. Listen to Norman and use your brain for higher-value tasks.

Screed over.  Back to Curious:the other thing Leslie really gets wrong (at least implicitly) is a failure to categorize information in any way.  Especially with the later discussion of the “Boring” conference (wherein attendees present on illustrious topics like the best way to insert toast into a generic toaster), Leslie seems to launch a quasi-populist celebration of knowledge for its own sake regardless of utility – there is a (weak) supporting argument of the benefits of serendipity.

I think Peter Thiel does a much better job on similar lines in Zero to One when he discusses, for example, the dichotomy between secrets about people and natural secrets.

Leslie presents absolutely no framework for directing curiosity in a useful way, which contrasts with Thomas Kuhn’s solid (if long-winded) arguments in The Structure of Scientific Revolutions (Kuhn review + notes) about why paradigms are actually necessary for progress, even if they’re wrong – summarized nicely on page 109 of that book:

“paradigms provide scientists not only with a map but also with some of the directions essential for map-making.  

In learning a paradigm the scientist acquires theory, methods, and standards together.”


Then again, there’s various quotes from Ben Franklin overviewed in Isaacson’s biography “Benjamin Franklin: An American Life” (BfAAL review – not worth reading).  Franklin’s beliefs on science and the utility thereof, per Isaacson:

“science should be pursued initially for pure fascination and curiosity, and then practical uses would eventually flow from what was discovered.”  

On balloons: while he saw no immediate purpose, he thought they might

“pave the way to some discoveries in natural philosophy of which at present we have no conception… important consequences that no one can foresee.”  

Another quote:

“what is the use of a newborn baby?”


“It does not seem to me a good reason to decline prosecuting a new experiment which apparently increases the power of man over matter until we can see to what use that power may be applied.  

When we have learned to manage it, we may hope some time or other to find uses for it, as men have done for magnetism or electricity, of which the first experiments were mere matters of amusement.”

Back to Leslie.  There is a nice line on page 145:

“highly curious people, who have carefully cultivated their long-term memories, live in a kind of augmented reality; everything they see is overlaid with additional layers of meaning and possibility.”

Well, again, only if what you’ve overlaid your mind with is useful.  A lot of knowledge simply isn’tuseful.  If we’re talking mental models, then yes, absolutely – as I’ve been putting together PAA, I’ve noticed more and more, on a daily basis, anything someone says I can reference some research on.

The rest of the book is not super noteworthy… a few things he mentioned – first, he recommends being both broad and deep, a “foxhog,” calling Darwin, Munger, and Nate Silver examples thereof.  Second, he emphasizes the importance of asking “why” (ironically, given the earlier comment about memorization, which is the anti-why.) He cites Ben Franklin and Peter Thiel as intellectually curious people… and talks about Csikszentmihaly’s “flow” as well as referencing David Foster Wallace’s “This Is Water” speech (a good one) as an example of empathic curiosity… but honestly, I didn’t get much out of the last parts of the book.

First Read: 2015

Last Read: 2017

Number of Times Read: 2

Planning to Read Again?: no


Review Date: summer 2017

Notes Date: summer 2017