The unexpected effect on inmates of
changing to LED lighting
most of its effect straight down as well as
being cheaper to run and maintain. The interior
lights were being changed for purely financial
reasons. It was after they had been fitted that
it was noticed that there had been changes in
the level of vandalism and anti-social behaviour.
We decided it was worth investigating.
CR What was the aim of the research and
what did you set out to establish?
CW There had definitely been a change in the
level of behaviour at the prison. We wanted to
establish if there was a direct link between the
installation of new lighting in the cells at the
prison and a drop in aggression and vandalism
that occurred at the same time. We wanted to
discover if there were any other factors that
may have been responsible and if the effect
was temporary. It was a win-win situation as
there are good financial and environmental
reasons for the change and as the units are
made at HMP Dovegate, another SERCO
prison, it generated work for the inmates
there too.
Chris Welford is a business
psychologist and he has worked
extensively within SERCO prisons.
His original role was in assessing
and coaching senior managers and
during one of these interviews the
conversation touched on the effects
of light on the behaviour of people
in prison. This eventually led to Serco
commissioning research looking into
the effect of lighting on the behaviour
of inmates. It was done at HMP & YOI
Ashfield, an establishment that had
already been scheduled to have its
lighting upgraded to LED units. The
research didn’t prove conclusively
that there was a direct relationship
between the behaviour of inmates and
different lighting conditions but the
initial research proved so worthwhile
that it has paved the way for more
extensive study.
CR Were there any other behavioural
changes within the cells?
CW Yes, the inmates’ attempts to modify the
output of the lights reduced significantly. There
were less DIY diffusers and paper shades being
fitted and little or no or crayoning over the
fittings.
CR How did you go about establishing if
there was a real connection between the light
output from the LED units and the change in
behaviour and it was not just a coincidence?
CW We conducted a literature review
for research that had been published on
light levels and behaviour. We also searched
for any evidence that the observed change
in behaviour was anything more than a
coincidence; perhaps as a result of prisoners
CR What work was done to the lights at
HMP and YOI Ashfield and what was noticed?
CW For economic and social reasons the
exterior and interior lights were changed to
LED units. The social reasons were because
the nearby inhabitants were being subjected to
excess levels of light pollution by the security
lights that surrounded the prison. They were
originally of the halogen type that gave out
a large ball like area of yellow light, much of
which is reflected upwards. The new LED
exterior lighting has the benefits of directing
the Custodial Review
Page 22
realising that something positive was being
done for them, feeling less negative about
their environment and therefore treating the
new lights with some increased respect. Our
search found that there has been a reasonable
amount of information published over the last
20 years that suggests a connection between
light and behaviour. This convinced us to look
into the matter more thoroughly.
CR Was the colour temperature of light that
was being emitted by the LED looked into?
As a photographer I know that the colour
temperature can affect a picture to make it
look warm or cold.
CW Some work was done along those lines,
but ours was not a controlled experiment in
the respect that we had a range of cells with
the LEDs emitting different types of light or
lux levels. All we had was one set of cells with
the new LED lights fitted and one with the
old halogen type of light so we were unable
to research any difference in the lux or the
colour temperature. The research we had
found in our literature review suggested that
there was an effect on behaviour if the light
used were in the bluer end of the spectrum
when it created a more dynamic atmosphere
or the red end it creates a more relaxing
effect. One interesting piece of information
we found was that people who have insomnia
should not use computers or iPads late at
night as the light they produce is from the blue
end of the spectrum and this makes the brain
more active.
CR What about the type of inmate that you
were working with, did you establish if that
made a difference?
CW When we interviewed the inmates many
of them could not recall what the lights were
like before they were changed; indeed because
of the turnover of the population many of
them were not at the prison beforehand. So
we were unable to determine if there was an
effect regarding age or any other factors. The
conclusion we came to was that the change in
light had an effect that was beneficial, however
as Ashfield is a YOI with a fairly transient
population, it was not considered conclusive
and that we really needed a more stable
population to enable us to find out if it was the
light making the difference.
CR What did you do about discounting
other reasons for changes in behaviour?
CW I went into this study thinking that there
was probably another reason for the change in
behaviour, what we call a Hawthorne effect where being simply being studied or observed
is the trigger that changes behaviour. However
these were not found to be so. We are left
with very convincing reasons that it was the
type of light that created the change in the
levels of aggression and vandalism.
CR What are the plans to take this forward?
CW We now need to look at the effects
in a larger and more stable population so
we have determined that the next thing to
do is to track the changes in vandalism and
anti-social behaviour in an adult prison with
a low turnover of inmates. Another plan is to
look at the effect at the therapeutic prison in
Dovegate and see if the lighting change has any
effect on the inmates there; paying particular
attention to mood. This will be possible to
do as the lighting is already scheduled to be
changed for economic and environmental
reasons, so it would be an ideal opportunity
and environment to more accurately observe
any effect on behaviour. If we change the lights
one wing at a time it will give us the chance to
observe and record any changes to behaviour
and how long it lasts. LED lighting is due to
go into the rest of the Serco estate as well, so
we could end up with some substantial and
empirical evidence.
CR It lacks real scientific credibility though
doesn’t it?
CW Correct. It’s not approaching the
results expected from a double blind placebo
controlled test. But if we have results from
the attack figures and vandalism records, plus
interviews carried out before and after, and
then at regular intervals over the next months
it will give some very strong indicators. As the
main reason that the LEDs are being fitted is
economic and environmental, the result of this
research does not have to been seen in terms
Page 23
of success or failure. If it’s shown to be more
than a coincidence it creates an interesting
hypothesis that could be improved upon. In
the social science world this type of process is
called phenomenological. It not truly empirical
but it will provide a way of measuring the
effect of something of this nature and so is
quite important. If the change in the light
source results in lower expense due to
changes in mood then this is something we are
very interested in as it has both an economic
and a social benefit. We see opportunities for a
longitudinal study.
CR What about the future for this, as
there seems to be an effect that is beneficial
is it worth getting a university to do a
research project to discover the nuts and
bolts behind it?
CW Serco has a very pragmatic culture and
is not one wedded to copious amounts of blue
sky research just for the sake of it. I believe
there is value in investigating this further and
that some additional work would be beneficial
both to the company and the wider world.
Thank you for talking to the Review.
the Custodial Review