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38. A Paradigm for distinguishing Significant from Non Significant Visual Imapacts: Theory, Implementation, Case Histories

DescriptionThis paper reviews visual impact assessment and design review procedures in the UK and US. It discusses the problems presented by legal judgements being made on aesthetics in environmental impact assessments. It asks whether we can distinguish "significant" from "insignificant" visual impact in visual impact assessments with sufficient precision for legal purposes from a study of the built environment.
MethodologyThe paper refers to studies of environmental projects and includes case studies. Legal aspects of environmental impact aesthetics are given prominence. A statistical criterion for settling disputes about environmental aesthetics is proposed. The author relates the statistical model to a philosophical model.

Concludes that there are substantial difficulties arising on issues of subjectivity, vagueness of language, and measuring the intensity of visual impacts and summarises that:

  • aesthetic judgements have objective and subjective parts.
  • intensities of feelings can be expressed in terms of simple semantic differential ratings, and the attributes of the environments can be specified in terms of the mathematics of three dimensional space, materials and light.
  • estimates of the strengths of the relationship between feelings and environmental attributes can be determined through standardised mean contrasts d.
  • a threshold of 0.2 standardised mean differences of preference ratings between 'after' and 'before' scenes distinguishes significant from non-significant visual impacts.

General Considerations:

  • Considers that photomontages for existing situations and digital montages for proposed conditions are valid simulation media.
  • Considers that there is substantial consensus on the aesthetic merits of environmental scenes.
PublishedEnvironmental Impact Assessment Review 17 (4): 249-293
AuthorsA, E. Stamps, III
DateJuly 1997
Publisher Elsevier 
Price subscription c. £250 p.a. (4) 
KeywordsVisual Impacts/visual preference/visual environment 

Introduction covers much of the ground of the philosophy and theory of environmental aesthetics covered comprehensively elsewhere. Useful summary of Kant but interpretations of aesthetic judgements are open to question. The article does provide a useful summary of empirical research and methods in visual preference studies but the conclusions presented appear overly simplistic.

The author refers to Zimmerman and Zumbo (1993) in arguing for the validity of using normal parametric statistics to analyse semantic differential data which is ordinal.

ReferencesZimmerman, D.W. and Zumbo, B.D. (1993) "The relative power of parametric and non-parametric statistical methods. In G. Keven and C. Lewis (eds) A Handbook for Data Analysis in the Behavioural Sciences: Methodological Issues, Hillsdale NJ: Lawrence Erlbaum Associates.