Factors affecting visual inspection accuracy.

A four-fold classification of factors which might influence the extent of inspector accuracy is provided. It is emphasized that the influence of these factors has been mainly evaluated in the context of laboratory tasks which simulate real inspection tasks to a varying degree. For each of the four classes of factors one has been selected to illustrate its contribution to reducing inspector error. These are the inspector's visual acuity, the work-place lighting conditions, the time available for inspection and the provision of feedback or knowledge of results to the inspector. There is now sufficient evidence to confirm the advantages that can follow from careful consideration being given to these factors when designing or modifying industrial inspection tasks.