Untitled - Journal of Lighting Engineering

Heli NIKUNEN, Marjukka PUOLAKKA, A RANTAKALLIO, K KORPELA, Liisa HALONEN
inadequate.’ The pleasantness of the
lighting environment with the following
statement: ‘The lighting in the area is very
pleasant – very unpleasant.’ Finally,
perceived safety was assessed via the
following statement: ‘The feeling of safety
produced by the lighting is very good –
very weak.’ We evaluated the statements
using 7-point Likert scales. Also, though we
measured perceived restorativeness, the
results are not reported here. Besides
responding to the statements, the subjects
were also free to comment on the lighting
environment in their own words if they
wished to do so.
The perceived glare was measured by
having the subject walk one pole length and
look straight ahead as they normally would
do. The perceived glare, measured on a
0-3 scale (0= no glare, 3=very strong glare),
was written down in a graph by an assistant
who walked slightly behind the subject. A
sorter scale was used in order to make the
evaluation task easier.
We used single-item scales rather than
multi-item scales for the measurements as a
way of limiting the evaluation time. During
the cold and dark season it would have been
difficult to get willing subjects to
participate in a lengthy outdoor study.
3.4 Procedures
We conducted the experiments at the
beginning of November 2011, starting
around 6-7 PM, so that it was completely
dark. There was no snow on the ground and
the tests and measurements were carried out
in dry weather. There was still some foliage
on the trees and on the ground.
First, the participants were informed
about the test site locations and the contents
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of the test forms, which they filled in
themselves. The background data of the
subjects were recorded close to the test area
in order for their eyes to have time to adapt
to the lighting situation. The subjects could
walk freely around the test areas, but the
desired evaluation direction was indicated
on the test maps, and verbal reminders of
this were also given during the test. The
evaluation direction was chosen so that the
visual background was as similar as
possible between the test areas.
In Roihuvuori, the mean test duration
was approximately 40 minutes and half of
the subjects (14 out of 29) conducted the
test in reverse order (Area C first). In
Herttoniemi, the mean test duration was
approximately 25 minutes and all of the
subjects conducted the test in the same
order (D first). This was done to prevent the
subjects from perceiving the areas against
an undesired background prior to the study,
which may have affected the results. After
participating in the test, the subjects were
compensated with two film tickets.
3.5 Data processing
When examining multicollinearity, we
noted that Pearson’s product-moment
correlations did not exceed 0.9. The highest
significant value was 0.61. The Shapiro-
Wilk test indicated that some of the factors
were not normally distributed. Normality
corrections were performed, but they did
not result in normal distributions.
Therefore, the significant relationships
revealed by the linear regression analyses
were checked using the Spearman
correlation as well. Independent analyses
were performed because it was considered
important to get area-specific results.
Ingineria Iluminatului 2012; 14, 2: 33-46