Outdoor Lighting and Crime - Amper

DCPC (2001, p 14) discussed the observed attractiveness of urban centres with extended
shopping hours and entertainment facilities, but missed the point that bright lighting appears
to play an important or even essential role in the existence of this attractiveness. The
combined effects of pleasure, arousal and dominance influence behaviour in particular
environments (Mehrabian and Russell 1974). Mehrabian (1976) believed that lighting was a
chief factor in the impact of the environment on individuals, and put this in the context of an
inverted ‘U’ curve like the Yerkes-Dodson curve for human performance as a function of
arousal. This carries an implication that sufficiently high absolute or relative levels of light
may become unpleasant and repellent, and degrade visual performance, as is already well
known.
Summers and Hebert (2001) found that moderate extra lighting of specific merchandise
displays in shops did reliably affect customer behaviour in ways that appeared good for
business. The positive effect of light on trade has been known at least qualitatively for a long
time, and, reasonably, the lighting industry has prospered in meeting this need. Philips (2002)
recommended shop interior illuminances of 300 to 500 lux, with spotlighting for specific
displays. In the case of a jewellery shop,
“[An] entrance illuminated with a relatively high lighting level will serve to attract
customers from a distance”,
and for a shoe shop,
“Well-designed lighting creates shop-windows that sell. Potential customers will be
attracted to the window and then, it is hoped, persuaded to enter the shop. The main
obstacle to achieving this is the reflections in the window caused by bright daylight.
The task of providing enough brightness in the window is made particularly difficult
because of the mostly dark colours of the merchandise”.
Rarely is there any appropriate dimming of the window display lighting at night (not to be
confused with switching the display lighting off for part of the dark hours). Lit shop windows
tend to be overbright at night if facing directly on to a street or other outdoor area.
The business world is also quite open about the key role of lighting in the profitability of
shopping malls. For example, Horner (2002) described how an existing shopping mall lit
internally to about 40 lux (“a dingy look”) was given an unstated increase of illumination. In
the next two years, there was a one-third increase in traffic flow, sales increased 38%, fewer
elderly citizens had slip and fall accidents and insurance premiums were reduced, and the
result was a 19 percent increase in profit. Horner claimed that relighting of a car park at
another shopping mall had reduced vandalism and made the area safer.
Presuming that the trials were uncontrolled, descriptions like this raise an issue about current
business development practices. Little credence would be given in scientific work to
experiments lacking adequate controls and without competent statistical analysis of
probabilities of the results arising by chance. The results of such poor scientific practices are
demand lights to make things safer. It could be that no real crime has yet arrived…
but fear has nevertheless reached a "tipping point" and street lighting is demanded…
Crime and lighting arrive together, not in causative way ... the lighting doesn't cause
the crime ... but they arrive in unison and the two feed on one another just as an
epidemic is caused not only by germs, but by germs mixed with bad health habits.”
(Nusbaum 2001)
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