Determination of Counting Time in Visual Inspection

Abstract

A series of experiments was conducted to clarify the relationship between the time required and visual process for counting dots projected onto a screen. The eye movement of the subject on each experimental trial was recorded by the electro-oculograph method and eye mark recorder. According to the experimental results, the subject used two information processes depending on the number of dots and symmetry of patterns. Both latency and movement time depend on the configuration of dots in the sample. An excess number of saccades is one of the causes for miscounting. A model for estimating counting time was built on the basis of the findings obtained. The time estimated by the model, if the maximum number of saccades does not exceed the number of dots on each sample, may be taken as optimum counting time.