A paradigm for distinguishing significant from nonsignificant visual impacts: Theory, implementation, case histories

Review of visual impact assessment and design review procedures in the UK and the US indicates that there are substantial difficulties on issues of subjectivity, vagueness of language, and measuring the intensity of visual impacts. This article suggests that the intensity of visual impacts can be measured with a scientific paradigm of visual impact assessment. It is estimated that a threshold of 0.2 standardized mean differences of preference ratings between “after” and “before” scenes distinguishes significant from non-significant visual impacts. The paradigm is illustrated with three case histories and references to other studies of environmental projects or regulations.