Public perceptions of the significance of impacts can be a determining factor in the decision regarding the need for an EIA. In some cases public opinion is directly sought, but more often screening decisions are taken without direct public input. Indeed, the public may still be unaware of the development proposal. A study undertaken in England and Wales on urban development projects and the factors which affected screening decisions found that local planning authorities were influenced by local opposition in 33% of cases, despite almost no direct public input (Bennington, 1993).