University of Huddersfield
University of Huddersfield investigative psychology lecturer Dr Chris Street is making breakthroughs that are leading towards a clearer understanding of how humans tell lies and how their deceptions can be detected.
For more than 30 years it has been said that we should trust our hunches and
unconscious knowledge of body language.
Yet his work, described in a new journal article, shows that we would be better off consciously relying on a single "cue," such as whether or not a person is plainly thinking hard.
Yet his work, described in a new journal article, shows that we would be better off consciously relying on a single "cue," such as whether or not a person is plainly thinking hard.
But gathering reliable research data is a tricky proposition. To
begin with, a set of lies and truths need to be collected. Ideally,
participants should not be aware that they are taking part in experiments that
are dealing with the subject of truth and lies.
So Dr. Street and his colleague devised an ingenious and well-intentioned deception of their own that involved hiring a film studio in London and persuading passers-by to be interviewed for a "documentary" on tourism.
They were told by research assistants placed outside the studio
that the film makers were running out of time and asked if, in addition to
describing genuine travel experiences, they would talk about places they had
not actually visited. Inside the studio, the speakers were then interviewed by
a director who -- they supposed -- was unaware that they had agreed to lie on
film.
"The idea was that they were lying to someone that they
could potentially deceive. They were lying on behalf of another person, but the
lie was spontaneous and told with an intention to mislead," said Dr.
Street.
The sequence of filmed interviews that resulted from the experiment
constitutes a valuable body of material that is being made available to other
researchers in what is still the relatively new field of human lie detection.
For more than 30 years, the standard approach to tapping the
unconscious has been to use the "indirect lie detection" method.
"People are asked to rate some behaviour that is indirectly
related to deception," explained Dr. Street. "For example, does the
speaker appear to be thinking hard or not? The researcher then converts all
thinking-hard judgments into lie judgments and all not-thinking-hard judgments
into truth judgments."
The fact that these indirect judgments give better accuracy than
asking people to directly and explicitly rate statements as truth or lies has
been taken as evidence that people have innate, unconscious knowledge about
human deception.
Dr Street and his co-researcher and author Dr Daniel
Richardson, of University College London, have developed a different
explanation, which they explore in their new article in the Journal of
Experimental Psychology: Applied.
"Indirect lie detection does not access implicit knowledge,
but simply focuses the perceiver on more useful cues," write the authors.
It is an argument that could have real-world significance, in the training of
interrogators, for example.
"There has been a push in the literature suggesting that
indirect lie detection works and the reason is that it is unconscious -- so
people should not be making reasoned judgments but relying on their gut
feeling," said Dr. Street.
"But if our account is correct, that is a
very bad way to go."
He readily concedes that human lie detection -- while a
fascinating subject -- requires a great deal more research and is a long way
from infallibility.
"Typical accuracy rates are around 54%, reaching up to
around 60% with training. So there is unlikely to be a one-size-fits-all
strategy that gives us accuracy rates anything like what we would want in a
legal setting. The field needs to start considering how to improve clues to
deception, how to prevent raters from using less reliable clues, and to better
understand how information about the current context plays into that judgment.
"We often think of nonverbal behaviour when we think of
deception," continued Dr Street. "But it would be better to focus on
the content of the tale people are selling us, and asking if it is consistent
with other facts we know. But even then there is a large amount of room for
error."
If human lie detection has a long way to go and there is
probably a cap on the accuracy that can be achieved, could the polygraph
machine fill the gap? No, asserts Dr Street, adding that the British
Psychological Society is one body that has dismissed the polygraph as a tool
that will never be useful.
It purports to work by detecting anxiety.
"But are liars
more anxious than truth tellers?" said Dr Street. "The reality is no,
because often the reason we lie is that to tell the truth would be very
difficult and more anxiety-provoking than a lie."
