A New Look at Models of Visual Performance

In visual performance experiments, accuracy is as much a function of the relative worth of speed and accuracy as it is of visibility. In a task that consists of subtasks, such as comparing two lists, it may be necessary to explicitly model the effect of each subtasks visibility on speed and accuracy. Finally, changes in print may be significant in that they can lead to changes in visual performance without a corresponding change in visibility.

The current Commission Internationale de L'EClairage (CIE) model for visual performance, CIE 19/2, does not consider the above factors. Although we believe that the CIE model is not useful as an application model, we do feel that the general features of the visibility/visual performance relationship are clear and are important to lighting design. We close with a brief discussion of the failure of the RQQ #6 lighting recommendations to explicitly consider cost-effectiveness.