Can week-old pizza cause 
psychedelic hallucinations?

Does coffee makes you smarter

or does it just make you 
do dumb stuff faster?

Like much much of psychology itself,

questions like this can seem pretty intuitive.

I mean, people may not be the easiest 
organisms to understand, but...

You're a person, right?

So you must be qualified to draw, like,
some conclusions about other people,

and what makes them tick.

But it's important to realize that 
your intuition isn't always right.

In fact, sometimes it is exactly wrong,

and we tend to grossly underestimate 
the dangers of false intuition.

If you have some idea about a person and
their behavior that turns out to be right,

that reinforces your trust in your intuition.

Like if I warned my buddy Bob

against eating the deep-dish pizza 
that's been in the fridge for the past week,

but he eats it anyway and
soon starts to wig out,

I'm gonna say: "Dude, I told you so!"

But if I'm wrong, and he's totally fine,

I'll probably won't even
think about it ever again.

This is known as hindsight bias, 
or the "I-knew-it-all-along" phenomenon.

This doesn't mean that common sense is wrong,

it just mean that our intuitive sense

more easily describes what JUST happened 
than what WILL happen in the future.

Another reason you can't 
blindly trust your intuition

is your natural tendency toward overconfidence.

Sometimes, you just really, really 
feel like you're right about people

when actually, you're really, really wrong!

We've all been there...

We also tend to perceive order in random events,

which can lead to false assumptions.

For example, if you flip a coin five times,

you have equal chances of getting all tails 
as you do getting alternating heads and tails,

but we see the series of five tails 
as something unusual, as a streak,

and thus, giving that result some kind of 
meaning that it very definitely does not have.

That is why we have the methods and safeguards

of psychological research and experimentation,

and the glorious process of scientific inquiry.

They help us to get around these problems

and basically, save the study of our 
minds from the stupidity of our minds.

So I hope that it won't be a spoiler if I 
tell you now that pizza won't make you trip,

and coffee doesn't make you smart. Sorry.

[on-screen animations and 
ribbons of science sentences]

Title screen says "Episode 2: 
Research & Experimentation."

In most ways, psychological research

is no different than in the 
other scientific discipline.

Like, step one is always figuring out how to 
ask general questions about your subject,

and turn them into measurable, 
testable propositions.

This is called "operationalizing" your questions.

So you know how the scientific method works.

It starts with a question and a theory.

And I don't mean theory in the 
sense of like, a hunch that says

"a quad-shot of espresso 
makes you think better."

Instead, in science, a theory is what explains 
and organizes lots of different observations

and predicts outcomes.

And when you come up 
with a testable prediction,

that's your hypothesis.

Once your theory and hypothesis are in place

you need a clear and common 
language to report them with.

So, for example,
defining exactly what you mean

by "thinking better" with 
your espresso hypothesis

would allow other researchers 
to replicate the experiment.

And replication is key.

You can watch a person exhibit 
a certain behavior once,

and it won't prove very much.

But if you keep getting consistent results 
even as you change subjects or situations,

you're probably onto something.

This is a problem with one popular
type of psychological research:

case studies, which take an 
in-depth look at one individual.

Case studies can sometimes be misleading,

because by their nature, 
they can't be replicated;

so, they run the risk of over-generalizing.

Still, they're good at showing 
us what CAN happen,

and end up framing questions for more 
extensive and generalizable studies.

They're also often memorable

and a great story-telling device psychologists
use to observe and describe behavior.

Like, say, the smell of coffee makes 
Carl suddenly anxious and irritable.

That obviously doesn't mean that it 
has the same effect on everyone.

In fact, Carl has terrible memories
associated with that smell,

and so his case is actually quite rare.

Poor Carl... :(

But, you will still have to look at lots of

other cases to determine that conclusively.

Another popular method of psychological 
research is naturalistic observation,

where researchers simply watch 
behavior in a natural environment,

whether that's chimps poking 
anthills in the jungle,

kids clowning in a classroom, 
or drunk dudes yelling at soccer games.

The idea is to let the subjects 
just "do their thing"

without trying to manipulate 
or control the situation.

So yeah, basically just spying on people.

Like case studies, naturalistic observations 
are great at describing behavior,

but they're very limited in explaining it.

Psychologists can also collect behavioral
data using surveys or interviews,

asking people to report 
their opinions and behaviors.

Sexuality researcher Alfred Kinsey
famously used this technique

when he surveyed thousands of men 
and women on their sexual history

and published his findings.

in a pair of revolutionary texts: 
"Sexual Behavior in the Human Male"

and "Sexual Behavior in the Human Female."

Surveys are a great way to access people's

consciously held attitudes and beliefs,

but how to ask the questions can be tricky;
subtle word choices can influence results.

For example, more forceful 
words like "ban" or "censor"

may elicit different reactions
than "limit" or "not allow."

Asking: "Do you believe in space aliens?" 
is a much different question than

"Do you think that there is intelligent 
life somewhere else in the universe?"

It's the same question, but in the first, 
the subject may assume that you mean

"aliens visiting the Earth 
and making crop circles

and abducting people and poking them."

And if how you phrase surveys is important,

so is who you ask.

I could ask a room full of students at a pacifist 
club what they think about arms control,

but the results wouldn't be a representative 
measure of where the students stand,

because there's a pretty clear
sampling bias at work here.

To fairly represent a population,
I'd need to give a random sample

where all members of the target group

(in this case, students) had an equal chance
of being selected to answer the question.

So, once you've described behavior

with surveys, case studies, 
or naturalistic observation,

you can start making sense out of it 
and even predict future behavior.

One way to do that is to look at

how one trait or behavior is related 
to another or how they correlate.

So let's get back to my buddy Bob,

who seems to think that his refrigerator
is actually some kind of time machine

that can preserve food indefinitely.

Let's say that Bob is just tucked into 
a lunch of questionable leftovers...

Pizza that may very well have 
had a little bit of fungus on it...

But he was hungry. And lazy.
And so he doused it in sriracha.

Suddenly, he starts seeing things.

Green armadillos with laser-beam-eyes.

From here we can deduce that eating 
unknown fungus predicts hallucination.

That's a correlation; 
but correlation is not causation.

Yes, it makes sense that eating questionable 
fungus would cause hallucinations,

but it's possible that Bob was already 
on the verge of a psychotic episode

and those fuzzy left-overs were actually benign!

Or, they could be an entirely 
different factor involved,

like maybe he hadn't slept in 72 hours

or had an intense migraine coming on,

and one of those factors 
caused his hallucinations.

It's tempting to draw 
conclusions from correlations,

but it's super important to remember

that correlations predict the POSSIBILITY 
of a cause-and-effect relationships;

they can not prove them.

So we've talked about how to describe 
behavior without manipulating it,

and how to make connections and 
predictions from those findings,

but that can only take you so far.

To really get to the bottom of 
cause-and-effect behaviors,

you're gonna have to start experimenting.

Experiments allow investigators
to isolate different effects

by manipulating an independent variable

and keeping all other variables constant
(or as constant as you can).

This means that they need at least two groups:

the experimental group, which is 
gonna get "messed with";

and the control group, which is 
not going to get "messed with".

Just as surveys use random samples,

experimental researchers need to 
randomly assign participants to each group

to minimize potential confounding variables 
or outside factors that may skew the results.

You don't want all grumpy teenagers in one group

and wealthy Japanese servers
in the other; they gotta mingle.

Sometimes one or both groups are not
informed about what's actually being tested.

For example, researchers can test
how substances affect people

by comparing their effects to
placebos, or inert substances.

And often, the researchers themselves

don't know which group is experimental
and which is control,

so they don't unintentionally influence
the results through their own behavior.

In which case, it's called...

You guessed it! A double-blind procedure.

So let's put these ideas into practice
in our own little experiment.

Like all good work, it starts with a question.

So the other day, my friend 
Bernice and I were debating.

We were debating coffee 
and its effect on the brain.

Personally, she's convinced that coffee 
helps her focus and think better,

but I get all jittery, like a caged meerkat 
and can't focus on anything.

And because we know that over-confidence 
can lead to belief that are not true,

we decided to do some critical thinking.

So let's figure out our question:

"Do humans solve problems 
faster when given caffeine?"

Now we've got to boil that down 
into a testable prediction.

Remember: Keep it clear, simple, and 
eloquent so that it can be replicated.

"Caffeine makes me smarter" 
is not a great hypothesis.

A better one would be, say...

"Adults humans given caffeine will navigate 
a maze faster than humans not given caffeine."

The caffeine dosage is your independent
variable (the thing that you can change).

So, you'll need some coffee.

Your result or dependent variable--

(the thing that depends on 
the thing that you can change),

is going to be the speed at which the 
subject navigates this giant corn maze.

Go out on the street, wrangle up a 
bunch of different kinds of people,

and randomly assign them 
into three different groups.

Also at this point, the American 
Psychological Association suggests

that you acquire everyone's 
informed consent to participate.

You don't want to force anyone
to be in your experiment,

no matter how cool you think it is.

So the control group gets 
a placebo (in this case, decaf).

Experimental group 1 gets 
a low dose of caffeine,

which we'll define at 100mg

(just an eye opener, 
like a cup of coffee's worth).

Experimental group 2 gets 500 mg

(more than a quad-shot of espresso
dumped in a Red Bull).

Once you dose everyone, 
turn them loose in the maze

and wait at the other end with a stopwatch.

All that's left is to measure your 
results from the three different groups

and compare them, just to see if 
there were any conclusive results.

If the highly-dosed folks got through it

twice as fast as the low dose, placebo groups

then Bernice's hypothesis was correct

and she can rub my face in it, 
saying she was right all along,

but really, that would just be 
the warm flush of hindsight bias

telling her something she didn't 
really know until we tested it.

Then, because we've used clear 
language in defining our parameters,

other curious minds can easily 
replicate this experiment and

we can eventually pool all the data together,

and have something solid to say about what
that macchiato was doing to your cognition.

Or at least the speed at which 
you can run through a maze.

Science!

Probably the best tool that you have
for understanding other people.

Thanks for watching this episode
of Crash Course Psychology!

If you've paid attention,

you've learned how to apply the scientific
method to psychological research

through case studies, naturalistic observation, 
surveys and interviews, and experimentation.

You've also learned about different 
kinds of bias in experimentation,

and how research practices help us avoid them.

Thanks specially to our Subbable subscribers,

who make this and all of Crash Course possible.

If you'd like to contribute to help us keep 
Crash Course going and also get awesome perks,

like an autographed science poster or 
even be animated into an upcoming episode

go to subbable.com/crashcourse to find out how.

[Host reads the credits]