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.