Theories and Principles
As other reviews of some of these issues before have found, some lines of enquiry have been followed up in depth and extensively, while others have barely been touched upon.
There are a number of different theoretical stances which lie behind approaches to research in landscape perception and aesthetics. Foster (1991) has explored aesthetics and the natural environment from a philosopher's viewpoint, following Berleant (1992) and others. Bruce, Green and Georgeson (1996) take a view of visual perception based primarily on physiological psychology. The Kaplans (e.g. Kaplan, Kaplan and Brown, 1989) take a view dominated by environmental psychology, and Nasar's (1988) edited papers on environmental research include the view of psychologists such as the Kaplans as well as planners, landscape architects, architects and geographers, important among them Appleton. Research by foresters has predominantly followed a psychophysical line, based on techniques developed by Daniel and Boster (1976) and others, emphasising the objective properties of landscape as the basis for aesthetic preference. Each discipline tends to have its own favoured methods.
Foster (1991) starts with a reinterpretation of Kant and Schopenhauer and discusses the influence of the (misguided as she sees it) art/nature divide in aesthetic theories on perceiving the natural environment. Foster claims that aesthetic judgments are about clarification not adjudication, and they are non-logical, non-scientific and singular. She questions whether aesthetic appreciation is necessarily aesthetically satisfying and asks what function pleasure and ethics play in aesthetics. She draws attention to the role in environmental perception of non-objects such as seasonal change, weather change, etc., and the neglected senses such as smell and taste. She usefully points out that the changeability of a given natural environment makes judgments of it of limited temporal applicability. She claims abstract ideas or cultural context are not necessary for an aesthetic response and promotes appreciation and judgement which is neither bound to art nor to science.
Bruce, Green and Georgeson (1994) take a fresh look at Gibson's theories of perception and affordance. Gibson says the world, not the retinal image, is the starting point for vision and claims that perception is direct and unmediated by inference and problem-solving. Traditional perceptual theory, by contrast, holds that perception is indirect and mediated by higher cognitive processes. Bruce et al. take a middle view - it is likely that cognitive activities are intimately involved in at least some aspects of human perception. Their physiological study of visual perception points to some useful ways of understanding landscape perception. The optic flow field is seen as vital (Gibson claims movement is essential for seeing) and it is likely that optic flow over-specifies the world - we are presented with a wealth of information and need active or "directed" perception in order to select between multiple sources of information. We may combine different sources or transfer from one to another according to circumstances. Marr's development of Gibson's ideas (see Bruce et al., 1996) suggest that early visual processing involves a 'primal sketch', a viewer-centred representation of what is seen, which is subsequently developed into a '3-D model' which allows object recognition when the image viewed matches a representation stored in the brain which is already known.
Bruce et al. suggest that different perceptual tasks may tap different visual processes - there may be, for example, a "motor" visual system we use to hit a ball and a separate "cognitive" visual system we use to steer a car. There is some empirical evidence for this, e.g. in the phenomenon of "blindsight", whereby a person with a damaged visual cortex can point to the location of an element in a region of the visual field in which they are convinced that they are blind.
This starts to point to some other theories, more bound to empirical work than Foster's philosophical stance. Seamon, Marsh and Brody (1984) have produced evidence (based on looking at simple polygons, not complex landscapes) that there is a difference in physiological process between judgments of 'affect' (do I like it?) and 'recognition' (do I recognise it?), where the first happens a great deal faster (4 times faster) than recognition. This raises the whole issue of affect and cognition in landscape perception and preference. Zajonc (see Seamon et al., 1984, Parsons, 1991) has suggested that preference is all about affect. Ulrich (Parsons, 1991) similarly proposes that the initial response to an environment is one of generalised affect, which can be independent of and primary to cognition. The Kaplans (in Nasar, 1988) assert that there is an intimate relationship between cognition and affect and that there is more to cognition than conscious thought. They consider facets of 'affect' as pleasure/pain/interest and divide cognition into 'constant' (good, bad and interesting) and 'process' (managing uncertainty or risk, recognising, predicting and evaluating).
Bruce et al. (1996) similarly talk about the importance of human cognition in enabling us to plan, reflect and reminisce. The question is, how does perception and preference draw on affect and cognition, and how does this relate to aesthetics? There is no universally accepted definition of aesthetic response, although psychologists in general tend to the view that it is related to preference. Berleant (1992) asserts that aesthetics involve content and meaning along with form, in contrast with Foster's view. Bourassa (1991), similarly, sees ethics and aesthetics as linked. Yet the work of neurophysiologists as well as environmental psychologists suggests that the emotional or affective response may be as vital to preference (and therefore to aesthetics, if we see these two as linked) as any cognitive or rational process, and may even be a vital part of early (possibly instinctive) response. Ulrich defines an aesthetic response as like-dislike affect associated with other pleasurable feelings and physiological responding (Parsons, 1991).
Evidently there is no single philosophical or theoretical approach to landscape aesthetics and perception, but several possible approaches which might be useful models. The role of affect and cognition is important, as is the engagement with the real world, not just the visual. The latter points to issues of multisensory and phenomenological investigations which explore how perception influences decision-making and action. The following explores some of the key empirical work on landscape preference which has attempted to investigate and elucidate these issues.