There are lots of different ways that we can
come to understand things about the world.
Typically we rely on our own insight and experience,
and what others tell us, and this is fine
most of the time.
However it can also lead to serious mistakes
because these everyday methods are sometimes
prone to bias.
Let’s take the example of psychic ability.
Some people claim to have a psychic ability
to predict crime or uncover who the perpetrator
of a particular crime is.
When these claims are looked at more carefully,
however, we often find that a psychic might
make any number of predictions about crimes.
However, they then only publicize the predictions
that turn out to be true.
So what looks like an uncanny ability to predict
the unpredictable might just be down to chance,
as they only highlight those outcomes that
happen to be confirmed.
Richard Wiseman of the University of Hertfordshire
and colleagues conducted an experiment in
which they asked psychics to make predictions
about some real life crimes.
They found that the proportions of accurate
predictions were no better than chance.
However, tellingly, the psychics involved
in the study appeared to believe they had
successfully demonstrated their psychic powers.
One even went on national television claiming
that the experiment proved that he did have
psychic powers, despite the opposite being
the case.
Wiseman argued that people might get this
false impression of success because of the
tendency to forget about all of the inaccurate
predictions while at the same time highlighting
and elaborating on predictions that turned
out, by chance, to be correct.
That is to say – the psychics here aren’t
necessarily charlatans in the sense that they
genuinely appeared to believe in their own
powers.
So, how can we strip away the sort of biases
that can mislead us regarding the truth of
what’s going on?
One answer is that we can employ the scientific
method.
The scientific method is just about observing
things in a systematic way.
So how can we do this?
First, we would bring in some independent
observers.
Second, we would make sure that we completely
controlled everything about the situation
that we could.
Third, we would run lots and lots of trials.
Fourth, we would use statistical techniques
to test our predictions about what it is that
we are studying.
We don't just focus on those outcomes that
support our predictions, we look at all of
the outcomes and use statistics to tell us
whether any differences we observe are likely
to be due to chance alone or some other factor.
We then publicly report our methods and results
after peer review so that other researchers
can critically analyse what we’ve done,
in order to identify any flaws or alternative
explanations for our findings.
And then, ideally, we'd repeat the whole process
lots of times under different contexts and
with different researchers.
This is called replication.
Fundamentally, the scientific method is a
much more reliable way of determining what’s
likely to be true about the world than relying
on our own experiences, anecdotal evidence,
and the like.
There are drawbacks to using the scientific
method of course: it’s expensive, it’s
time consuming, and it’s not always possible
to control things to the degree required.
However, if we’re dealing with issues where
knowing the truth of the matter really matters
– for example, where the truth could mean
the difference between a dangerous criminal
being captured or not being captured, or someone
going to prison or not going to prison
– then it’s worth seeing what the scientific
method can tell us.
And that’s what this course is about.
We’ll be reviewing a range of behavioural
studies published in the scientific literature
to see what they can tell us about how we
should run our criminal justice systems.
And what we’ll discover is that sometimes
what even criminal justice professionals believe
to be true, a belief that could be based on
decades of personal experience, can turn out
to be wrong.
