one of fiction's most popular characters,

having been portrayed by over 200 actors

on the screen over the years

and having served as the inspiration for other characters

such as Batman and Adrian Monk.

And it's no wonder why we're so fascinated with him.

Yes, his stories contain lots of mystery and adventure,

but he's also a character who can make logical deductions from the most scant evidence,

and we find that inherently fascinating.

We find characters who are hyper-intelligent to be really interesting.

And what's better about Sherlock Holmes,

he's not superhuman, he is human.

Which leads me to the point of this video,

because if you're anything like me,

you've probably gone beyond simple fascination with the character at one point or another

and thought to yourself, how can I think like Sherlock Holmes?

You know, without all the sociopathic tendencies

and the substance abuses, just the good parts.

Well that is what I want to explore in this video,

and by the end of it you're going to understand three of the core mental strategies

that Holmes brought to his cases,

deep observation, skepticism, and probabilistic thinking.

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The first strategy on my list

is also probably the most famous one;

Holmes is a keen observer of his environment.

He doesn't just casually see or perceive his environment

like the rest of us; he observes it with scrutiny,

taking it all in and storing away details

that other people may miss it entirely or forget it quickly.

This well trained power of observation

allows him to tie together all those small details

in order to make conclusions.

And this is a skill that's useful

not just in detective work, but in almost any field.

So here's how you can build this skill for yourself.

First, be an active participant

in whatever's going on in your life.

Try to be as present-minded as you can.

When you're having a conversation with somebody else,

try to listen actively.

Try to formulate questions in your head

to dig into what they're saying.

And when you're traveling around

or going about your business, don't be staring at your phone

or otherwise dividing up your attention.

Try to be present minded and observe your environment.

Like many other cognitive skills,

observation is a habit that can be strengthened over time.

The author W.I.B. Beveridge puts it really well

in his book The Art of Scientific Investigation:

Training in observation follows the same principles as training in any activity。

"At first, one must do things consciously and laboriously,

but with practice the activities gradually become automatic

and unconscious, and a habit is established."

Right now, most of us aren't very well trained in the art of observation.

We divide up our attention; we multitask.

So again, if you want to get better at this,

be as present-minded as you can.

And to get specific, I do want to give you

one little challenge to take away from this video.

Next time you sit down to eat,

next time you sit down at a table,

don't take out your phone at all.

Not only will this force you to be

present-minded and not dividing your attention

with your phone and whoever's at the table,

but it'll also force you to make conversation

so that you'll be building your social skills as well.

Now, aside from mindfulness, there's one other

critical piece to building those observational skills,

and that's to gain experience in whatever field that you want be

really perceptive and observational in.

Experts naturally pick out details

that are relevant to them in situations and environments

that the average person just isn't going to see.

Think about how a,

actually I can't say this word, what is it?

Traceur.

Yeah that, somebody who practices the art of parkour

would look at the average urban environment

versus how a normal pedestrian would look at it.

While you and I would just see

roads and sidewalks and buildings and other people,

somebody who's an expert in parkour

is going to see a lot more, naturally.

They're going to see the most efficient way

to get from Point A to Point B,

whether it's ducking under a railing

or vaulting over something, climbing up a wall.

And you and I are just not going to see that.

Now, this tip is pretty related

to another quality that Sherlock Holmes emphasizes a lot,

a background knowledge across many different fields

that's both deep, and most importantly,

according to Holmes himself, well curated.

This is a concept that Holmes calls the "brain-attic,"

and here's how he describes it in A Study in Scarlet:

"I consider that a man's brain

originally is like a little, empty attic,

and you have to stock it with such furniture as you choose.

A fool takes in all lumber of every sort that he comes across,

so that the knowledge which might be useful to him gets crowded out,

or at best is jumbled up with a lot of other things,

so that he has difficulty in laying his hands upon it.

Now, the skillful workman is very careful indeed

as to what he takes into his brain-attic."

Now, I don't think you need to be paranoid about taking in the wrong things,

as the brain is pretty elastic

and you're really not going to "fill it up" as such.

But you do want to make sure that you're focusing

on the most important things for the majority of your time.

Most of us have that one person in our life

that's a master of useless trivia,

but hasn't really put a whole lot of time

into developing a useful skill.

Don't be that person.

Put the majority of your time and energy and focus

into gaining useful information.

And when you do, learn actively;

take notes, summarize what you learn,

and try to put it into practice as soon as you can.

Additionally, you want to be exploring

lots of other subjects that are somehow related to your main subject.

Doing this will form lots of additional neural connections

and build a really deep web of information in your brain.

And memories that have lots of different connections

are both more likely to be retrieved

and more likely to be combined with the problem at hand

to come up with a creative solution.

As the famous investor and partner of Warren Buffet Charlie Munger said,

"The first rule is that you can't really know anything

if you just remember isolated facts"and try and bang them back.

If the facts don't hang together on a lattice-work of theory,

you don't have them in a usable form."

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The second mental strategy of Sherlock Holmes

that we're going to cover today is skepticism.

The Athenian playwright Euripides once wrote that

"Man's most valuable trait is a judicious sense of what not to believe."

And Sherlock Holmes brings a natural skepticism

to every case that he faces.

He listens to his clients or observes the details

of a case or a crime scene deeply and scientifically,

but he also compares what he's seen and observed

to his current model of reality and all of his background knowledge.

But on the other hand, as studies have found,

most of us can't help but instinctively believe what we hear right when we hear it,

especially if we're put in stressful situations or we're put under time pressure.

Not only that, but our brains also rely

on lots of different little cognitive biases and heuristics, mental shortcuts

that are very useful in many different situations,

especially as the human species evolved,

but that can also lead to incorrect decision-making and bad thinking.

For instance, we tend to weight

the information that is available to us much too heavily,

that's called the availability heuristic.

We also tend to believe things

if we know a lot of other people believe them,

the bandwagon effect.

And we also rely heavily on stereotypes.

In fact, a recent study in The Journal of Criminology,

which I think Holmes probably would have read,

found that certain physical traits are correlated with sentencing decisions.

This being despite the fact that logically,

we all know that our physical appearance

has nothing to do with whether or not we committed a crime.

And that isn't even the half of it.

Environmental factors that you wouldn't expect

also have the ability to really influence our decision-making.

For instance, prospective students

that visit a college campus on a cloudy day

are more likely to enroll in that college

than if they did on a sunny day.

And people who are affected by seasonal affective disorder

tend to make more risk-averse decisions with their money

during the winter months than they do during the summer months.

Now with all these natural flaws in our thinking,

how can we actually think objectively?

One powerful strategy comes from the author Maria Konnikova,

who wrote the book Mastermind: How to Think Like Sherlock Holmes,

which was, as you might guess,

one of the big inspirations for this video.

Her advice is to actively work

on noticing what is priming your thoughts

and influencing your decisions.

As she states in the book, "A prime stops being a prime

"once we're aware of its existence.

Bring any attention at all to the priming mechanism，

and you'll likely find the effect go down to zero.

When we're aware of the reason for our action,

it stops influencing us."

And as we'll add on to that piece of advice,

make sure that when you come to a conclusion,

you can point to the logical deduction

or the observable evidence that caused it.

If you can't, then it's a good sign

that you're relying on one of those cognitive biases

and that you should probably work through the problem a little bit more deliberately again.

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Finally, Sherlock Holmes' ability to make deductions and solve cases

hinges on his ability to think in terms of probabilities.

What is most likely to happen?

When Holmes is working on a case, he thinks

like a scientist, and he uses the scientific method,

forming hypotheses as he goes along

and testing them against new data as it's discovered.

And since that data is almost never 100% conclusive,

he generates many different hypotheses,

and then he tries to figure out which one is the most likely candidate.

Now, this probabilistic thinking is also called inductive reasoning.

While deductive reasoning uses certainty and sound logic

to reach conclusions that are 100% true,

inductive reasoning asks what is the mostly likely answer,

given the facts?

And again, since most complex problems in life

usually rely on incomplete information,

you need to be able to use inductive reasoning

just as much as you need to be able to use deductive reasoning.

Now if you want to see this probabilistic thinking in action

one of the Holmes stories, "The Sign of Four," has a great example.

It starts when Dr. Watson hands Holmes a pocket watch

and asks what he can deduce from it.

After looking the watch over for a few seconds,

Holmes replies with quite a lot of information, actually.

That the watch was originally owned by Watson's father,

then passed down to his elder brother.

Also that his older brother had certain periods of his life

that were prosperous, but spent most of it in poverty

and probably ended up dying of alcoholism.

Now, this deduction turns out to be extremely accurate,

and at first Watson is offended,

thinking that Holmes had actually dug into his personal life