Landscape Preference and Perception

Introduction

Factors in landscape preference

Need for public preference input to landscape evaluations

Preference versus measurement techniques

Paradigms in landscape evaluations

Evolutionary concepts

Socio-demographic factors in landscape preference

Theory behind the influence of socio-demographic characteristics

Familiarity

Age

Consensus

The ability of landscape architects to predict public preference

Medium of presentation

Photographs as landscape surrogates

Perceptual distortions

Validity of photographic simulation

Panoramic verses regular prints - framing

Results of experiments into photographic surrogates of landscapes

Experiment of Shuttleworth, 1980a

Experiment of Kroh and Gimblett, 1992

Experiment of Stamps, 1992

Best method of photographic simulation

Abstraction of computer generated images

Other visual and non-visual effects

Non-visual effects

Labels in the landscape

Sound and motion

Looking time - a null indicator

Visual effects

Complexity

Mystery

Focality, ground texture and depth

Prospect and refuge

Effects of and preferences for landscapes

Landscape descriptor dimensions

Preference predictors

Characteristics of high and low preference natural landscapes

View classification experiment

The difference between what people like and what they look at

Personal Construct Theory

Geographic information systems and cognitive criteria

Measurement of cognitive criteria using GIS

References

Introduction

"It has been assumed pretty generally that the Greeks and Romans had little attraction for the beauties of rugged nature. On the contrary, it has been argued that the appreciation of the majesty of the mountains and the grandeur of the sea of wholly of modern origin, a development of northern romanticism. Thus a fundamental difference has been assumed to exist between the ancient and modern attitude toward nature" (Hyde, 1915).

In any given landscape evaluation there will be a mixture of these factors internal and external to the observer. In some circumstances the former may dominate the response, in others the latter may dominate. In other words, in some circumstances beauty will reside more in landscape and in others the eye of the beholder will be more critical in influencing landscape judgements (Dearden, 1987).

Factors in landscape preference

There are five general factors of design elements for assessing landscape preference: the characteristics of the observers; the medium selected for presentation; the response format; the relevant environmental attributes of the settings; the nature of the transaction with the specific setting (Hetherington et al, 1993). The first two of these are also mentioned by Tips and Savasdisara (1986) as being the two basic factors of influence: the interviewed subjects and uses their characteristics, such as age, sex, familiarity with landscapes, nationality or occupation; the characteristics and the origin of the rated landscape scenes and the dimensions of the medium used for presentations. These factors are described in the sections on socio-demographic influences and on the medium of presentation.

Need for public preference input to landscape evaluations

The sampling of both landscapes and people is equally vital to adequate research in landscape perception; it would be misleading to sample one systematically while ignoring the sampling of the other (Shuttleworth, 1980a). A large number of studies explain preference responses solely as a function of of the physical components of natural and man-made landscapes. Many ignore in their analysis the fact that preferences are expressed by people and that people with different backgrounds and experiences probably have unique preferences (Lyons, 1983).

A variety of cultural, social and demographic factors have been shown to be factors in the environmental and aesthetic preferences of the general public (Anderson, 1981; Lyons, 1983). It would also appear possible that landscape appreciation is linked more to perceptions of the subtleties of landscape and the interaction between elements than to the presence or absence of single or readily observable landscape attributes (Penning-Rowsell, 1982).

Professionals in the field of design and environmental planning are seen to have a more sensitive appreciation of landscape quality and are also thought to be able to articulate their feelings more expressively (Dearden, 1981b).Citizen interest is thought by some to be lacking in landscape evaluations because of the inherently subjective and somewhat intangible nature of the problem. However researchers who have used the public in landscape assessments have found them to be highly motivated, interested in the topic and willing to donate their time irrespective of social, economic and educational backgrounds (Dearden, 1981b).

Preference versus measurement techniques

Measurement approaches to visual landscape quality assessment relies on the reduction of the landscape to its constituent components which are allocated points according to the relative contribution of each to landscape quality. Preference approaches make no attempt to single out landscape components or to allocate them points. Instead, it is the total appearance of the tract that is judged. Aside from philosophic arguments against the reductionist approach implicit in measurement methods, preference methods are likely to prove more valid (Dearden, 1981b).

Aesthetic response is defined as preference or like-dislike affect in association with pleasurable feelings and neurophysiological activity elicited by visual encounter with an environment (Ulrich, 1986).

Psychophysical models strive to bridge the gap between the landscape emphasis of the ecological and formal approaches and the observer-emphasis of the psychophysical and phenomenological approaches. They often involve large samples of both landscapes and observers, and try to establish statistical relationships between observer preferences and landscape characteristics. They have proved quite successful in accounting for variance between different landscape traits in terms of landscape characteristics (Dearden, 1987).

There is little danger that one assessment approach will be settled upon to the exclusion of all others. The diversity of assessment methods which continue to emerge will testify to that. If any theory should come to dominate the field it will do so by reflecting and explaining all the various ideas, perceptions, and methods which are possible, rather than by expecting all aesthetic experience to conform to a particular model or rationale (Ribe, 1982).

Paradigms in landscape evaluations

A paradigm is defined as (Chambers, 1992):

"a basic theory, a conceptual framework within which scientific theories are constructed".

Four general paradigms of landscape perception research are noted by Zube et al (1982). They are the expert, the psychophysical, the cognitive and the experiential paradigms.

Expert paradigm

Involving evaluation of landscape quality by skilled and trained observers. Wise resource management techniques are assumed to have intrinsic aesthetic effects.

Psychophysical paradigm

Involving assessment through testing the general public or selected population's evaluations of landscape aesthetic qualities or of specific landscape properties. External landscape properties are assumed to bear a correlational relationship to observer evaluations and behaviour.

Cognitive paradigm

Involves a search for human meaning associated with landscapes or landscape properties, information is received by the human observer, and in conjunction with past experience, future expectation, and sociocultural conditioning, lends meaning to landscape.

Experiential paradigm

considers landscape values to be based on the experience of the human-landscape interaction, whereby both are shaping and being shaped in the interactive process.

The cognitive paradigm differs from both the expert and psychophysical paradigms in providing a theoretical foundation for landscape perception, by attempting to explain why people prefer different landscapes. It attempts to bridge the gap between subjectivity and objectivity by using a theoretical model from which assumptions can be made and tested using empirical techniques (Kroh and Gimblett, 1992).

The discussion of landscape perception paradigms and disciplines demonstrates a difference between journals having theoretical and applications orientations. Geographic journals tend to emphasise the experiential approach to landscape perception, while the behavioural and recreation journals concentrate on cognitive and psychophysical approaches; the management and applications journals, particularly within forestry and landscape, place heavy emphasis first on expert and subsequently on psychophysical approaches. This might suggest that landscape managers, planners and designers have little interest in theoretical literature, especially in the experiential and cognitive paradigms, and particularly if it is lacking in suggestions of practical use (Zube et al, 1982).

Evolutionary concepts

Man's origins necessitated that he became a highly visual animal, and that an ability to handle large quantities of visual landscape information has been essential for our species' long term survival (Ulrich, 1977). Evolutionary history has left its mark on contemporary humans in the form of strong biases concerning perception and preference. People should prefer landscape scenes having qualities which aid in making sense of the information present (Ulrich, 1977).

If a given scene has attributes which facilitate its comprehension, then a creature who likes to acquire large amounts of knowledge should favour the scene. To be preferred, therefore, a scene should not only present information, but it should also be identifiable and easily grasped. A scene that is ambiguous and resists identification, or which places very high processing demands on the observer, should be less preferred.

Socio-demographic factors in landscape perception

Many different social and demographic factors have been shown to influence the perception of landscape. Age and familiarity are noted a being of high influence and are discussed later. Land Use Consultants (1971) noted the following association and factors as influential to the perception of landscape: an awareness of historical/cultural associations; well known names; home environment, cultural environment; education; experience of other landscapes; knowledge of landscape; familiarity of landscape; role (e.g. on holiday); position relative to landscape; and immediate state of mind.

Previous experience of landscapes

Previous experience of landscapes has a "profound influence" on human perception and preference, according to Balling and Falk (1982), who state that landscape preference is undoubtably not simply a function of some innate preference. Purcell (1992) comments that humans experience each new or previously encountered landscape within the context of mental models of previous landscape experience.

Gender

Gender is a trait which reflects the amount and nature of societal learning, which may affect landscape preference. It is also an important social differentiator of people's attitudes toward the natural world (Lyons, 1983). Indeed, Hull and Stewart (1995) showed that men and women look at different objects while walking, with men more likely to be viewing the ground, topography and ephemeral objects.

Education

Another important social differentiator is education (Lyons, 1983) - in a study by Balling and Falk (1982) college students had more favourable attitudes towards wilderness than secondary school students. Education can also be linked to the perception of crowding in a recreational landscape. Glyptis (1991) found that higher educated people were less tolerant of crowding than those with less education. However, this was not found in a study based on a loch and forest landscape (Wherrett, 1994) where higher educated people were more likely to accept a higher level or crowding.

Environmental awareness

It has been suggested that there is an environmentally aware public and an environmentally unaware public, who possess quite different perceptions (Dearden, 1981b). The former are often members of environmental organisations, a factor which has been shown to indicate a variation in attitude towards natural landscapes (Harvey, 1995).

Cross cultural differences

Zube and Pitt (1981) looked at cross-cultural differences. They found that many native and non-native groups showed preferences for landscapes similar to their home environments. The differences between native and non-native groups was larger than that between American and British subject groups. However, it would appear that the similarities across cultures in terms of perception and cognition are much more impressive than the differences (Ulrich, 1977).

Theory behind the influence of socio-demographic characteristics

There is now considerable evidence that a domain of knowledge such as that associated with landscapes or more generally outdoor scenes is represented in memory by mental structures (referred to as knowledge structures) containing two types of knowledge. The first is based on the overlap in the attributes of or the family resemblances between all the previously experienced instances of that domain of knowledge. The second type of knowledge organises memory for large numbers of individual instances, that is memories about experience of particular instances and events. Generic knowledge structures contain default values for relevant attributes and relationships (Purcell, 1992).

At the perceptual level, a landscape might be represented in terms of colours, shapes and textures at a number of scales; at more abstract levels information about topography, naturalness or degree of man-induced change could be represented, while at the most abstract level meanings associated with the word landscape or the types of activities that could occur in landscapes would be represented (Purcell, 1992).

Results show that when asked to make a judgement of the typicality of a landscape, respondents use a relatively abstract set of attributes which can result in similar ranges of typicality being found independent of the geographic location of the landscapes being assessed (Purcell, 1992).

Familiarity

Knowledge and familiarity of a landscape are noted as factors affecting perceptions of landscapes (Land Use Consultants, 1971). If familiarity with landscape influences perception, and if there are clearcut regional differences, then generic landscape models may not be viable (Wellman and Buhyoff, 1980). Several studies have looked at this factor (e.g. Lyons, 1983; Wellman and Buhyoff, 1983) with differing results.

The study of Wellman and Buhyoff (1980) showed that the subjects did not demonstrate greater visual preference for a particular regional landscape even if they were informed beforehand of the geographic differences. Also, the subjects from widely different geographic regions evaluated the landscapes, in terms of preference, in essentially the same manner, suggesting that regional familiarity may not be a serious problem for landscape preference researchers (Wellman and Buhyoff, 1980).

On the other hand, the study of Lyons (1983) which examined preferences of college students from different regional biomes, showed that preferences were highest for the most familiar biome. The subjects from coniferous forest areas showed a significantly higher preference for living in nontropical, forested landscapes than did the desert dwellers. These findings support the hypothesis that a person's landscape preference is strongly influenced by his or her residential experience in different biomes (Lyons, 1983).

As an example, Balling and Falk (1982) showed that foresters, who were the most familiar of their study groups with a range of natural environments, showed the highest preference among the adult groups for each of the biomes.

The risk and uncertainty connotations of some natural settings are important ingredients of natural landscape preferences. Moreover the `alarming, deterring' or `stimulating, exciting' character of certain landscape features depends in personal capacity for accepting risk or challenge (Bernaldez et al, 1987).

Age

Age-related differences in landscape preference can be seen in the studies of Lyons (1983), Bernaldez et al (1987) and Balling and Falk (1982). Balling and Falk (1982) found significant age related changes in the preference for landscapes that differ in terms of floristic organisation and that underlying preference can be modified by experiences across the life span.

In the study of Lyons (1983) preference scores for vegetational biomes decreased for young children, then stabilised or rose for college-aged and adult subjects, dropping again for elderly subjects. The coefficient of variation around the age group mean tended to decrease with age; young children as a group were more enthusiastic and less consistent in assessing landscapes than were older subjects (Lyons, 1983). The differences in preference could have resulted from the way that different ages used the rating scale.

Multi-variate analysis of the preference responses of children to landscape photographs allowed the identification of three independent preference dimensions: the 1st and 3rd dimensions (illuminated vs shadowed; rough, harsh us bland, smooth texture or relief) were considered as forms of a more general risk/uncertainty factor often influencing landscape preference. Younger children (11 years old) showed less preference for both shadowed, less illuminated scenes (1st dimension) and harsh, rough scenes with aggressive forms (3rd dimension) than older children (16 years old). There were no significant differences for the 2nd dimension (landscape diversity) (Bernaldez et al, 1987).

Consensus

Landscape preference studies should not rely exclusively on general rankings of preference, but should also consider other trends of variation and eventually compare individual patterns of selection. If only consensus aspects are examined (e.g. group preference rank), idiosyncratic features remain ignored. The partition of the total variation between consensus scales and other trends of variation will probably depend on the degree of sociocultural homogeneity of the group of respondents (Abello et al, 1986).

The subjects' variance in the relative evaluation of appraisal characteristics may have very different origins. It may be related to sociocultural or psychological factors that affect landscape preference as described by a number of authors (Abello et al, 1986).

To evaluate levels of consensus the `modal percentage' is determined, being the proportion of respondents giving the modal evaluative rating (Penning-Rowsell, 1982).

Reasons for the real variation in consensus levels remain elusive. Evidence suggests little overall correlation between perceived attractiveness and consensus levels, although the more `extreme' evaluations rarely attract majority support. Consensus does not increase with greater familiarity. Indeed those admitting less knowledge of local landscapes show greater consensus in their generally cautious and conservative evaluations. Those with the greatest landscape knowledge are more critical of its various qualities so that their responses show greater variance. The degree of consensus on evaluation therefore generally declines with increasing landscape familiarity, although not always sufficiently to be statistically significant given the available sample sizes (Penning-Rowsell, 1982).

The ability of landscape architects to predict public preference

The purpose of the research was to ascertain whether landscape architects could determine the rank order of a series of landscapes as they were preferred by another group of subjects, based on knowledge of what this group had said they liked and did not like about the landscapes (Buhyoff et al, 1978).

The results showed that a group of landscape architects, given general information as to what a sample of people like and don't like about a set of photographs, can come quite close to reproducing the client group's rank orderings of those photographs (Buhyoff et al, 1978). Planners may be able to assess people's preferences by asking them what they do and do not like about landscapes, but they cannot and should not rely on their own preferences in planning for people (Buhyoff et al, 1978). It is desirable for planners to make some assessment of people's expectations and preferences rather than relying on their own judgement (Buhyoff et al, 1978).

Medium of presentation

A prevalent though unstated assumption throughout much of the empirical research in environmental preference is that the more closely experimental conditions represent `real-life' experiences, the more accurately the results will reflect `real-life' responses to the studied environment (Hetherington et al, 1993). However, there is the question of whether people do respond the same to a real landscape as to a simulation (Kroh and Gimblett, 1992).

Photographs as landscape surrogates

The use of pictures as surrogates for real landscape has often raised objections in the sense that photographs are less complex, less multi-dimensional, and offer less interaction than do real scenes (Abello et al, 1986). Pocock (1982) states that however good the simulated landscape may be, " it does not obscure the fact that a photograph is totally unable to convey the life of the scene: unable to discriminate: it merely records everything at one instant".

The use of photographs in recent work concerned with environmental aesthetics, perception and preferences has been commonplace, because photographs can be used with greater economy, speed and control than can real-world situations. This approach follows the long tradition in psychological studies and experimental aesthetics of using stimulus substitutes (Shuttleworth, 1980a). However, photographs are useful in landscape management decisions only if respondents rank pictures in approximately the same order as they rank the actual scenes (Shafer and Brush, 1977). A number of researchers have reported high correlations between photo-based judgements and on-site judgements of scenic beauty (Hetherington et al, 1993). Shafer and Brush (1977) found that respondents reacted essentially the same way to both the scene and the photograph.

Perceptual distortions

It must be remembered that when a surrogate environmental display such as a photograph is used, perceptual distortions can and do occur. The most obvious source of variation between photographs of a view and the view as seen on the ground is caused simply by the fact that the two may differ in content. The eye takes in a much larger field of vision than the camera, having a very wide lateral cone of vision. This deficiency can be overcome with the use of panoramic photographs (Shuttleworth, 1980a) which are now far less costly than they were some 15 years ago.

There is a need to provide constancy scaling and perspective resolution aids in photographs if they are to allow the viewer to perceive accurately objects as the same solid visual shapes, with their characteristic properties of colour, shape and distance, as perceived in the original (Shuttleworth, 1980a).

A fundamental source of perceptual distortion lies in the differing physical nature of views and photographs. The view consists of three-dimensional objects, stationary or moving, at various distances in space, whereas the photograph is merely a two-dimensional image of that reality obtained by the projection of the view through a more or less complex optical system. It must be remembered that retinal images, although the result of "seeing" as commonly understood, occur merely as one link in the chain of events which constitutes the process of seeing (Shuttleworth, 1980a).

Validity of photographic simulation

Several authors have tested the validity of using photographs as simulations of real landscapes. Thayer et al (1976) tested the model of Shafer et al (1969) and found it to be a valid predictor of perceived landscape beauty in photographs; Stamps (1990) conducted a meta-analysis of papers discussing preferences obtained in situ and preferences obtained through photographs, resulting in a combined correlation of 0.86; the conclusion reached by Dunn (1976) was that photographs may be used to accurately represent landscapes.

However, not all authors agree with this result. Kroh and Gimblett (1992) found that people do not respond similarly to an on-site landscape experience and a simulation and that classifications drawn from field experience differ from laboratory ones because of the impact of multi-sensory stimuli. The utility of the validity research is limited to the static environment, because the represented landscapes did not contain any prominently dynamic elements (Hetherington et al, 1993) and thus the preference measured is that of the static landscape (Kroh and Gimblett, 1992). It has been concluded that the static surrogate (colour slides) do not sufficiently preserve dynamic environmental features, while the dynamic surrogate (video) produces flow-related differences in ratings of scenic beauty.

Shuttleworth (1980a) looked at eight investigations of the validity of photographic surrogates. All the studies provide evidence that scenic quality evaluations based on photographs are similar to ratings made by different observers in the field, and provide some tentative evidence that not only overall responses but also the details of those responses are similar. The simulations were found to be more limited when used with a feature checklist for assessing the effect of specific landscape features on scenic quality. They concluded that photographic simulation proved most reliable in dealing with the overall perception of the landscape, but less reliable when dealing with perception of detail elements and characteristics in the landscape (Shuttleworth, 1980a).

Panoramic verses regular prints - framing

Although the retinal image is the physiological basis for seeing, it is not the image experienced by the viewer. Therefore, despite the intrinsic similarity of photographs to retinal images, photographic simulations should not be attempts to mimic "peculiarities of the retinal image" (Nassauer, 1983; Shuttleworth, 1980a).

People may frame selected views in field experience just as a photographer does in shooting a photograph. That a photographer would select the same frame, or isolate the same landscape elements, as every other viewer of a given landscape seems unlikely (Nassauer, 1983).When a great deal of the landscape is included in the photographic frame, the viewer may scan the photograph much as she/he might scan the landscape, selecting from a range of stimuli those that are important. Narrower, more select frames may enhance the distancing effect of photographs (Nassauer, 1983). The elements included in the photograph will be limited by the horizontal range of the view, and by the frame selected by the photographer.

Analysis of the data suggests that, under some conditions, panoramic slide sets elicit responses different from responses to wide-angle slides (Nassauer, 1983). In the study of Nassauer (1983) panoramic slide sets received significantly higher ratings than wide-angle slides for scenic landscapes displaying dominant horizontal landscape form. This framing effect is apparently operational only in scenic landscapes. In non-scenic landscapes, viewer reaction to compositional factors like framing may be relatively less important than reaction to landscape content (Nassauer, 1983).

Results of experiments into photographic surrogates of landscapes

Experiment of Shuttleworth, 1980a

The results of this experiment showed that there were no differences between the verbal response patterns and the overall evaluations of scenic quality of randomly chosen subgroups of respondents viewing the scenes in the field. The results indicated that there were very few differences of significance between the reactions to and perceptions of the landscapes either when viewed in the field or as photographs. The results also suggest that black and white photographs tended to induce more extreme and more highly differentiated responses than colour photographs, and that the latter related more closely to field responses (Shuttleworth, 1980a).

Experiment of Kroh and Gimblett, 1992

While a preference for actual versus simulated experience is evident, the rank order of scenes showed little correlation between site and laboratory. The laboratory test data exhibited a much lower level of content words and a higher measure of diversity than the field data. The limited use of content words indicates that landscape simulations were less evocative of sensory awareness. The higher levels of diversity indicate that, while sensory stimuli were limited, it was more difficult for respondents to form consensus on each scene (Kroh and Gimblett, 1992). The content analysis of on-site data exhibits a richer vocabulary more expressive of a simulating experience. Although more content words were found, the measure of diversity was lower than for the laboratory and relatively consistent for all scenes (Kroh and Gimblett, 1992).

Experiment of Stamps, 1992

Stamps (1992) tried to find out if people could distinguish alterations from reality in photographs. In the study only 14% of the responses were correct identifications of photographic alteration. It was found that the effects of simulation on judgements of environmental preference are in the order of 5 to 10% of preference variance (Stamps, 1993).

Best method of photographic simulation

The landscapes must be depicted by colour photographs, to maintain a potentially important source of landscape variety in the study (Shuttleworth, 1980a) - colour clearly gives the viewer more information about the landscape than a black and white image (Nassauer, 1983).

Different photographic framing choices can elicit different viewer responses to a landscape. Framing formats that create large images with broad horizontal ranges may be superior for simulating field experience. Panoramic slide sets can achieve this effect (Nassauer, 1983). Shuttleworth (1980a) stated that the landscapes must be depicted by wide-angle photographs to provide the lateral and foreground context in each of the views without apparent distortion of the actual scale relationships that are found in the direct perception of landscapes. It is suggested by Nassauer (1983) that conventions should be developed for making framing decisions.

Abstraction of computer generated images

Researchers have represented outdoor scenes with a spectrum of computer graphical techniques including: simple perspective line drawings, perspective block diagrams in which a grid of distorted squares gives the perception of terrain, highly realistic representations which account for shadows, texture of grass and forests and the effects of haze and clouds on visibility (Killeen and Buhyoff, 1983).

Significant but moderately strong association was found between the artist's sketches and both the original slides and the computer-drawn lines. No statistically significant association exists between the slides and the computer-generated drawings (Killeen and Buhyoff, 1983).

The level of abstraction can significantly alter the views on ranking a set of abstract representations of landscapes. Therefore, when using modern tools, such as computer plotter drawings to facilitate the study of particular factors influencing landscape preference, such as topography, presence of vegetation, human influences etc. care should be taken to abstract from reality along dimensions that do not interact strongly with the factor studied (Tips and Savasdisara, 1986). Abstraction is not inherently bad, but achieving less abstract mappings is desirable, because it is likely to yield more universally understandable Visualisations (Bishop and Karadagli, 1996).

It has been demonstrated that there are differences in the perceptual effectiveness of computer simulations among different types of computer generated images. Image processing elicited the most similar responses to real images. Wire frames, the most abstracted images, yielded the most different responses. Surface model and COMB images showed a modest similarity to real images, although they were somewhat abstracted (Oh, 1994).

Wire frame simulations have a lack of colour and detail. Surface model simulations can be `artificial and cartoonish' and have insufficient detail for sky, vegetation and landscape structures. Combinations of surface model images and scanned photo images (COMB) also have insufficient detail. Image processing simulations, however, give a very credible simulation (Oh, 1994). In fact only image processing among the four methods was successful in separating the visual attractiveness of one landscape from another in simulations (Oh, 1994).

Other visual and non-visual effects

Landscape perceptual preference involves much more than a visual evaluation of a static scene. Human preference for landscape is directly linked to the nature of people as multi-sensory beings. The verbal descriptions given by respondents in this research indicate that tactile, dynamic features significantly contribute to preference (Kroh and Gimblett, 1992). Although the evaluation may be based primarily on the visual aspects of the setting, other aspects, such as sound and smell also contribute to landscape perception (Balling and Falk, 1982). The effects that are looked at here include labelling of the landscapes, sound and motion, looking time (relating to viewing slides), complexity, mystery and prospect and refuge. Some of these factors cannot be used in a surrogate landscape study, in particular sound and motion require different media of presentation than the standard photograph or slide.

Non-visual effects

Labels in the landscape

The influence on aesthetic values of the names of land areas has been explored by Anderson (1981). The results of analysis of variance on the Scenic Beauty Estimation (as described in Schroeder and Daniel, 1981) or SBE scores for each slide demonstrate that scenic quality judgements were affected by the land use designations, as well as by the appearance of the slides. The wilderness area and national park labels consistently elevated evaluations of landscape quality, while the leased grazing range and commercial timber stand labels consistently reduced observers' judgements of attractiveness (Anderson, 1981).

These results may imply that for relatively high scenic quality landscapes, an enhancing label can improve aesthetic value, while a detracting label will have only a slight effect of an attractive scene but a much stronger negative effect on a relatively ugly landscape (Anderson, 1981).

One explanation for this is that the labels induce expectations of different levels of scenic quality in the landscape. When the appearance of the landscape confirms these expectations, the effect of the names is more pronounced than when the actual scene is not congruent with the expectation (Anderson, 1981). Implied naturalness and economic connotations resulting from the labels also affect scenic quality rankings.

Sound and motion

Acoustic impacts on aesthetic evaluations of different settings have been addressed in only a handful of studies. This lack of research may reflect a consensus among researchers that visual features of a setting are paramount in determining aesthetic response to it (Anderson et al, 1983).

Sound and the interaction of sound and site is highly significant in explaining variance in a study by Anderson et al (1983). They found that there is an interaction between acoustic and other features of a setting that modifies the effect of different sounds in determining the quality of the setting. Sounds that, in the abstract might be regarded as enhancing improved wooded, natural, and heavily vegetated urban settings, but not built up sites such as city centres (Anderson et al, 1983).

The results of Hetherington et al (1993) indicate that both sound and motion influence judgements of scenic beauty. Motion without sound produces similar results to the static digitised image condition, while the motion with sound and the original video results suggested a consistent polynomial relationship between perceived scenic beauty and flow. The static surrogate (slides or photographs) does not sufficiently preserve dynamic environmental features, while the dynamic surrogate (video) preserves flow related differences in ratings of scenic beauty (Hetherington et al, 1993).

Looking time - a null indicator

It was hypothesised that differences would be found in preferences for landscapes in direct proportion to the time spent looking at visual representation of those landscapes (Wade, 1982). However, the linear relationship between average looking time and the average preference rank showed that as preference for landscapes used increases, time spent looking at them tends to decrease. Through talking with some of the subjects, the investigator learned that the subjects looked at some of the slides longer because they were more interested in or curious about the landscape than in actually showing a preference for it as a scenic vista. A few subjects, nevertheless, ranked them fairly high because of the contrast they presented in colour and texture. Some slides were ranked low because the landscapes had too much open area (Wade, 1982). The main conclusion from the study was that there is no relationship between looking time and preference rank.

Visual effects

Complexity

It has been found that individuals tend to prefer complex natural landscapes over less complex ones; complexity has been shown to be an important predictor in landscape preference evaluation. The hypothesis that individuals generally prefer natural environments of high complexity is supported by the results of Shutte and Malouff (1986). Orland et al (1995) used a computer model in an attempt to simulate human preference based on complexity and scenic beauty.

Computer measures of complexity included colour, edges, fractal dimension, standard deviation, entropy, huffman encoding and run-length encoding. These six measures constituted the computer complexity measure, this was used to look at preferences for pine forest images. In the preference results old growth forest received the highest ratings for beauty and complexity and the new growth forest received the lowest. This contradicts the computer measures, which showed that the new forest images contained the highest degree of complexity and the old growth forest the least (Orland et al, 1995),

While the computer measures appear to be valid in measuring what they purport to measure, it is unsure what ought to be measured to capture the visual differences that trigger human subjective responses. It is disturbing that while perceived complexity seems so consistently related to perceived beauty, the measure bears no relationship to the image-based physical measurement. It is possible that in the absence of a commonly used conception of scenic complexity the human respondents are simply doing what they are used to - rating their underlying preference for the scene (Orland et al, 1995).

Complexity affects not only the amount of information in a landscape scene, but also the time and effort required to process the display. Results have consistently indicated that preference and complexity are related in a hyperbolic manner. High preference is associated with a moderate level of complexity, while low preference tends to be linked with the extremes of either low or high complexity (Ulrich, 1977). However, research has shown that human perception is characterised by a bias favouring patterned information; under certain conditions, high complexity displays can evoke high preference (Ulrich, 1977).

Mystery

Mystery is defined as the "degree to which you can gain more information by proceeding further into the scene" (Lynch and Gimblett, 1992). Mystery has been found to be a consistently perceived attribute of landscapes. The following structural relationships have been found to be important (Lynch and Gimblett, 1992):

o perception of mystery decreases with perceived distance;

o the perception of mystery declines as perceived screening declines;

o as perceived spatial definition increases, the perception of mystery increases;

o perceived physical access increases the perception of mystery.

While mystery alone does not have total influence in the overall preference for landscape, it has been shown to be a major contributor (Lynch and Gimblett, 1992). Mystery contributes some ambiguity and uncertainty to visual displays; therefore, certain instances of high mystery should have a negative effect on aesthetic preference (Ulrich, 1977).

The compositional qualities of landscape relevant to mystery include: distance from forest stands; edge diversity; and absorptive or reflective qualities such as those inherent in water features. Four landscape variables of mystery are spatial definition, physical accessibility, distance of view and partial screening (Lynch and Gimblett, 1992). These are defined as follows:

• Partial screening is defined as the degree to which views of the larger landscape are visually obstructed or obscured;
• Distance of view is measured from the viewer to the nearest forest stand;
• Spatial definition is the degree to which landscape elements surround the observer;
• Physical accessibility is defined by an apparent means of moving through or into the landscape as a result of fine textured surfaces in the foreground plane.

Focality, ground texture and depth

Focality refers to the degree to which a scene contains a focal point, or area that attracts the viewer's attention. Focality is produced when lines, textures, landform contours, and other patterns direct the viewer's attention to a specific part of the scene (Ulrich, 1977).

Irregular textures present the viewer with unordered high complexity. Such displays should evoke low preference responses because they resist rapid and efficient comprehension. Surfaces that have even textures, or areas of textural homogeneity, should be accorded higher preference since the complexity is ordered (Ulrich, 1977).

Ground textural gradient is important in distance perception. A uniform, even texture preserves the sense of "continuous" ground surface which is necessary if distance is to be accurately perceived. Rough, irregular textures may disrupt a sense of continuous ground surface, thereby resulting in spatial ambiguities, lower legibility, and reduced preference (Ulrich, 1977).

If depth could not be perceived, landscape features would stand ambiguously in two dimensions; depth is linked to legibility through its effects on the scale of landscape elements (Ulrich, 1977).

Prospect and refuge

Prospect and refuge is concerned with the openness or enclosure of views and observation points. A study by Nasar et al (1983) examined this effect in terms of the effects on male and female subjects. Subjects rated the more open views as safer than the enclosed ones, with females assessing the safety lower than males. The preference score for females was higher from the protected location than the unprotected one, while the opposite was true for males (Nasar et al, 1983).

The observer's context (in this case location and sex) seemed to influence emotional response. The open view was judged as safer than the closed one, and this effect was more pronounced from an open observation point than from a protected one. This effect did not carry over to environmental preference, and males (unlike females) liked the setting with less refuge (Nasar et al, 1983).

Effects of and preferences for landscapes

A recent study examined post-surgical recovery data for patients in a suburban Pennsylvania hospital to determine whether assignment to a room with a window view of a natural setting might have therapeutic influences. These patients had significantly shorter hospital stays, less complications, higher morale and less pain killers. These findings strongly suggest that the view of trees had comparatively therapeutic influences of the patients (Ulrich, 1986).

Landscape descriptor dimensions

Hull and Buhyoff (1983) and Gobster and Chenoweth (1989) have divided landscape dimension into 2 or 3 types; the former use cognitive/psychological and physical/biometric measures, while the latter also use artistic measures.

Most terms can be classified as belonging to one of three "descriptor types": physical; artistic; and psychological. (Gobster and Chenoweth, 1989).

Physical descriptors relate to the external dimensions of the environment - what is "out there" versus what is "in the head". They have been used in expert assessments and in psychophysical studies of aesthetic preference.

Artistic descriptors refer to the formal or abstract, compositional dimensions of the landscape. Examples include unity, variety, vividness, line, colour, texture, contrast, harmony and integrity. They might be thought of as "higher order" constructs of physical landscape dimension - some argue that they have greater aesthetic relevance than basic physical dimensions; others argue that they discount the importance of detail, motion, ephemeral effects, and the emotional and expressive dimensions of landscapes.

Psychological descriptors refer to the psychological impacts that a landscape may have on those who observe or experience it. Studies of this dimension have been criticised because they do not relate to landscape dimensions which can be perceived or managed (Gobster and Chenoweth, 1989).

In contrast to studies of the physical and artistic dimensions of landscapes related to aesthetic quality, studies employing psychological descriptors tend to be less place oriented. Instead, the focus has been more on the outcomes of people's interactions with landscapes, and on the relationships between various psychological dimensions (Gobster and Chenoweth, 1989).

Typically, landscape dimensions fall into one of two general categories: cognitive and psychological constructs or physical and biometric measures. Cognitive dimensions are often studied in attempts to better understand and explain an observer's perceptions of aesthetic quality. Physical dimensions, on the other hand, are by nature more quantifiable and hence are often used to predict perceived aesthetic quality (Hull and Buhyoff, 1983). Complexity can be considered as a cognitive dimension with potentially measurable physical attributes (Hull and Buhyoff, 1983).

Preference predictors

The results of Calvin et al (1972) suggest that there may be two major dimensions which people use in their subjective assessments of natural beauty. The first was labelled natural scenic beauty; a basic factor in preference for natural scenery appears to be the location of a scene along a dimension from beautiful to ugly. A second factor in judging landscape scenery appears to be a natural force-natural tranquillity factor. Some scenes are regarded as tranquil, others as powerful.

The subjective quality of the landscape experience appears to be multidimensional. Mood, satisfaction, and scenic beauty appraisals covary over the course of the hiking experience. Because scenic beauty has a physical referent ( the landscape) it is arguably a more objective measure than are measures of mood and satisfaction, which do not have observable, physical referents (Hull and Stewart, 1995).

A distance landscape dimension was found to have a nonmonotonic predictive relationship with perceived scenic beauty. The implication of this nonmonotonicity is simply that the minimum or maximum influence of a landscape dimension can occur at some medium level of the dimension's range rather than at its extremes (Hull and Buhyoff, 1983). An equally important conclusion is that distance proved to be a very good predictor of perceived scenic beauty.

Characteristics of high and low preference natural landscapes

Ulrich (1977) developed a model of visual landscape preference. This model forecasts high preference for scenes with attributes which aid perception and comprehension or which convey an explicit anticipation that additional information can be gained by changing the vantage point. These legibility attributes are complexity, focality, ground surface texture, depth and mystery. A scene should be favoured if (Ulrich, 1977; 1986):

1. complexity, or the number of independently perceived elements in the scene, is moderate to high;

2. the complexity is structured to establish a focal point, and other order or patterning is also present;

3. there is a moderate to high level of depth that is clearly defined;

4. the ground surface has even or uniform length textures that are relatively smooth;

5. a deflected or curving sightline is present, conveying a sense that new landscape information lies immediately beyond the observer's visual bounds;

6. judged threat is negligible or absent.

The most powerful single variable found by Ulrich (1977) was mystery. The presence of this factor heightened attractiveness irrespective of the ranges of the legibility variables. This model illuminated the importance of informational determinants but in order to create a more complete model, statement regarding the effects of colour, water, and ephemeral landscape phenomena, such as clouds and sunsets, should be added (Ulrich, 1977).

View classification experiment

View classification attempted to explain some of the patterns of use on a nature trail and some of the connecting unofficial trails. The classification was fairly subjective, but was based on the amount of trees, water and mountains in a view. The results showed a preference for views enclosed by trees and views in the open countryside. While views of the open loch, pine forest and background mountains did well, views where the forest obscured the loch were not well liked (Wherrett, 1994). It is perhaps the sense of mystery that cannot be explored or a sense of threat which deters people from these views. As noted previously, it is the extreme views which score highly, while those which are merely "average" achieve only an average score.

The difference between what people like and what they look at

The operational definition of Hull and Stewart (1995) of the experience landscape has three parts: the encountered landscape, i.e. the views, people and objects seen; the sequence of which they are encountered; the feelings, thought and other subjective qualities that are experienced concurrently with these views. Three subjective qualities used in the study were mood, satisfaction and scenic beauty appraisal.

Neither scenic views nor ugly views dominated the landscape encountered while hiking. The majority of the encountered landscape is comprised of the more mundane views of the hiking trails, rocks, bushes, and other hikers near the trail - none of which were rated as being exceptionally scenic or ugly. Most attention seems to be directed forward - towards objects near the observer (Hull and Stewart, 1995).

Views containing water or mountains and valleys were rated as being more scenic than views containing ephemeral features, vegetation, or other people. In addition, persons felt significantly more satisfied and more excited when encountering mountains and valleys than when encountering other types of objects (Hull and Stewart, 1995). Results showed that scenic beauty and landscape preference are enhanced by the presence of ephemeral features, distant views, rugged mountains and water (Hull and Stewart, 1995).

In the study, people spent 60% of the time on objects less than 15 meters away, 20% less than 2 meters away and 40% within 5 meters. Attention was less frequently directed to objects in the middle ground (15 to 150 meters). 10% of the views were of objects between 150 and 1km away and more than 20% were of the distant background or horizon (Hull and Stewart, 1995).

The data suggested that the encountered landscape is comprised of views of the following objects: ground (24%), mountains and valleys (20%), trees, bushes, grasses and other vegetation (14%), water features (12%), ephemeral features, such as snow, wildlife and flowers (12%), other people in the landscape (10%) and other (such as signs, sky and views of oneself) (8%) (Hull and Stewart, 1995).

Personal Construct Theory

Personal construct theory (PCT) has a ability to link a person's image and attitude toward a landscape. The benefits of using GIS in presenting the results of perception exercises can be easily seen in the work of Harvey (1995) and others (e.g. Kliskey and Kearsley, 1993; Steinitz, 1990). PCT provides a systematic means of evaluation that relates the constructs used by individuals to a cognitive set which characterises group response to landscape (Fitzgibbon et al, 1985). PCT is based on the theory that "a persons processes are psychologically channelized by the ways in which he anticipates events" (Harvey, 1995).

GIS and cognitive criteria

Researchers in environmental perception have concluded that personal experience of landscape can be classed into four general categories: physiographical characteristics, the presence of specific physical features, cognitive variables and viewer interest (Kliskey and Kearsley, 1993; Baldwin et al, 1996). The work of Baldwin et al (1996) aimed to investigate the cognitive and digital interface of landscape value assessment by examining several elements of landscape experience to facilitate their inclusion in GIS.

Whilst the shapes and forms of the world surface can be modelled within the GIS environment it is not so simple to define the specific boundaries of mountains and valleys, plains and plateaus for digital analysis. The identification of the spatial extent of many classes of landscape feature (such as valley and hill) remains inconsistent between individual approaches. Uncertainty in feature definition arises in part because the same location can be considered part of a number of different features simultaneously. Landscape in the foreground of a view will inevitably be viewed at a contrasting scale to that which makes up a distance horizon (Baldwin et al, 1996).

It is believed that associations between the viewer position and the expected viewer satisfaction may be illustrated, and that the aesthetic experience may be determined from a combination of the texture and pattern of the land cover information as and the digital plan form of the viewshed. It is also believed that there are relationships between the number and shape of the horizons present within a landscape and the pleasure experienced by the viewer (Baldwin et al, 1996).

Measurement of cognitive criteria using GIS

Most GIS operations are deterministic and precise. It is difficult to represent a cognitive environment within a GIS. The paper of Baldwin et al (1996) explored some of the ways in which to use a GIS to subjectively analyse the human perception to landscape.

By identifying specific features and naming them according to their physiographical characteristics, it is suggested that it should be possible to relate cognitive information to such features in an effort to assess the differences in perceived contributions of both micro and macro landscape components within the viewshed. It may also be possible to class the feature as a polygon with an assigned dominance value where the difference in the feature value to that of the surrounding landscape would provide a means of categorising it as integrated, intrusive, dominant etc (Baldwin et al, 1996).

Physiographical characteristics of landscape cognition can be modelled using the technology associated with viewshed analysis. Relief, depth of view, horizon characteristics and shape could all be measured using GIS functionality. It is suggested that cognitive criteria such as drama, mystery and coherence may have measurable surrogates by using the modelled view as a basis for their definition (Baldwin et al, 1996). Some suggestions for such measurements using GIS are described below (Baldwin et al, 1996).

Relief

Relief is an ambiguous concept that is generally considered to be a function of elevation. Using distance and the viewing elevation data in conjunction with relief angles, a measure of relief may be derived which is sensitive to perspective. However, a better indicator of relief is volume (Baldwin et al, 1996).

Depth of view

It is simple to extract a summary depth of view from the viewing angle function. However, the appropriate inclusion and significance of the incorporation of such a measure within landscape value assessment remains unclear. An alternative approach may be to generate an area weighted mean value (from viewer to all points within the viewshed) or a standard deviation component for all such points (Baldwin et al, 1996).

Horizons

Characteristics of each horizon such as their smoothness and the number of times the horizon is broken could also be incorporated which would provide the first steps to producing a measure of horizon dominance and the subsequent description of individual horizon qualities which may affect view quality (Baldwin et al, 1996). Skyline extraction is not usually available within GIS functionality.

Drama

It is proposed that drama is a function of the corporate effects of physiographical, planimatric and cognitive criteria. It may be possible to assess drama within a GIS by categorising the viewshed into proximal, intermediate and distant viewing areas and combining this element with the maximum and minimum viewing angle. For example:

1) In the proximal viewing region (0-1km) drama may be created by the presence of a cliff or precipice where the angle of relief is significantly greater than the viewing angle. This could be seen as particularly dramatic.

2) In the middle region (1-5km) drama tends to be created by the presence of a peak or significant visible topographic variation to the surrounding area. The viewing angle would be closer to the relief angle and the drama would then be derived from a combination of angle, feature and scale information.

3) In the distant viewing area (5km - skyline horizon) drama is created by a large-scale landscape feature such as volcano or mountain range, and as a result, the impact of the viewing angle may be a lesser consideration. In this case, the skyline shape would be combined with view angle and relief components.

Mystery

By analysis of the horizon characteristics and masking of visible areas, it should be possible to generate a mystery component when combined with landsurface and landcover information.

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