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of the senses of subjects in the real world. However,
the requirements in terms of participants and landscape
samples may create some insurmountable practical diffi-
culties and arouse interest for environmental surrogates.
Simple photographs (Ryan, 1998; Nasar and Lin, 2003;
Bulut and Yilmaz, 2009), scanned and altered pho-
tographs (Wilson et al., 1995), colour slides (Herzog,
1985; Gregory and Davis, 1993; Le Lay et al., 2008),
360
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panoramic views (Meitner, 2004), visual simula-
tions (Kubota, 1997; Junker and Buchecker, 2008) and
specially-drawn sketches (House and Fordham, 1997)
have more or less frequently been used as visual media
for waterscape assessment.
Photographs are two-dimensional images, the con-
tent of which does not integrally convey 'the temporal
variety and visually dynamic qualities of many real-
world nature scenes - e.g., such as moving water surfaces,
wind-blown vegetation, and changes associated with
seasons' (Ulrich, 1981, p. 551). Therefore, numerous
studies have addressed the validity of photographs as a
medium for presentation of the environment. Although
surrogates may provoke perceptual distortion, individ-
ual responses to an actual physical setting are strongly
and positively correlated to responses based on a com-
prehensive photograph of the same scene (Shafer and
Richards, 1974; Daniel and Boster, 1976; Shuttleworth,
1980; Stewart et al., 1984; Nassauer, 1987; Trent et al.,
1987; Zube et al., 1987; Brown et al., 1988; Stamps, 1990;
Palmer and Hoffman, 2001). A meta-analysis of 11 papers
yielded 'a combined correlation of 0.86 between prefer-
ences obtained
in situ
and preferences obtained through
photographs' (Stamps, 1900, p. 907).
The great advantages of photo-based perceptual eval-
uation are the equivalence of presentation conditions
to respondents (Shuttleworth, 1980), the low costs of
(re)production and the easy access to and manipula-
tions of the media (Huang, 2004), the possibility to
present many identical landscapes to sample groups of
participants (Gregory and Davis, 1993). 'The selection of
particular stimulus photographs is critical for the eval-
uation of any hypothesis about the nature of people's
landscape preferences' (Wilson et al., 1995, p. 53). Scien-
tists, and not participants, choose what is presented: they
take the photographs or at least select them. However,
the reality is so complex that individual appreciations of
the same view may derive from very different criteria. To
reduce the bias of the observer and assess the importance
of a specific feature, commonly-used measures of central
tendency can be calculated using scores that are attributed
to a scene. As nothing forces the analyst to consider each of
the scenes individually, he may also distinguish different
groups of photographs according to defined criteria.
The investigator has to take into account several con-
straints. First, photographs have to depict most of the
variety in the outdoor scenes (Shafer and Richards, 1974).
The slides are taken from the ground, without using tele-
photo lenses (Shafer and Brush, 1977). They should show
an eye-level front view of the studied object, 'normally
from an obvious viewpoint such as a riverside track, stop-
bank, or bridge parapet' (Mosley, 1989, p. 6). They are
taken in clear weather and under similar lighting and sun
angle conditions, using the same film and camera (Ulrich,
1981; Mosley, 1989). Lack of sunlight lowers scenic beauty
(Brown and Daniel, 1991). No effort must be made to
compose scenes. Aesthetically spectacular scenes must be
avoided (Ulrich, 1981). No animals or people should be
visible, and human influences should be minimal in any of
the pictures (Ulrich, 1981; Herzog, 1985). The riverscape
structures presented by the photographs must be similar
in order to weaken the effect of factors such as depth of
field, perspective, or relative importance of background.
It can be asked to what extent photographs are needed
in studies on environmental perception and evaluation?
No protocol has been fixed at this time and stimu-
lus samples may vary considerably between 5 and 240
views, depending on the authors and the objects stud-
ied (Table 18.3). In order to diminish the specificity of
each scene and to test precise hypotheses, it is neces-
sary to present a reasonable number of photographs for
each type of riverscape and to calculate the mean of
the scores obtained. Two is a minimum, 4 to 5 should
provide a good set for a given riverscape type, allowing
for the assessment of the respective importance of the
intra- and the inter-types of variability. This being said,
Shafer and Brush (1977) suggested 'that 20 photographs
probably would be adequate for any one management
area' (p. 250). More than this makes the interview long
and fastidious, and the order of submission of the pho-
tographs may influence the perception ranking. Twenty
photos is a good compromise, thus indicating that not
more than 4 to 5 types of scenes can be tested in a
given survey.
18.3.2 Theattitudescales
There is no general agreement on the metrics used for
photo-questionnaires (Table 18.3). Many scales are com-
monly used in works of social psychology. Landscape
evaluation is often based on bi-polar scales built width
adjectives such as 'exciting', 'sad', or 'ugly'. Participants
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