Accurately measuring inspection time with computers

Abstract

Accurately measuring inspection time (IT) with computers requires several considerations. They are: 1) Screen redraw period; 2) Synchronous and timely image presentation; 3) Stimulus duration timing; 4) Image scale invariance; 5) Stan dardized presentation format (of which image scale invariance is a part). The first consideration dictates a minimum duration available for measuring IT. The second and third are necessary for accurate stimulus duration. The fourth is necessary to provide scale invariant images, that is, images with the same visual angle at a given viewing distance on any computer. And the fifth ensures that participants everywhere respond to the same task. Our computer program em- bodies these elements and we make it freely available to any interested party. Data to establish validity and reliability are presented, and normative data on 2518 participants aged 6 to 92 years are available.