Abstract

Visual information sampling efficiency is defined as the average fraction of the total visual information utilized by the observer to perform signal detection tasks and is found by measuring the performance of signal detection as a function of added visual noise (signal-to-noise ratio). A sampling efficiency of 100% has been demonstrated for normally-sighted observers, that is, they sampled all available visual information in the image.¹ Full efficiency was found over a variety of parameters; field of view, random versus regular dots distributions, varying luminance, and blurred dots. Low vision observers with either central or peripheral visual field loss would be suspected of reduced sampling efficiency. The visual field loss would force the observers to use a smaller region of visual field to sample the visual information. To the extent that an individual with visual field loss acquires less visual information in a single fixation (compared to the person with full visual fields), one would expect that more fixations are necessary to acquire all relevant information. As the number of required fixations increase, there would be a corresponding increase in the amount of information that must be committed to memory. These considerations led to the present study of whether observers with impaired information acquisition due to visual field loss are less efficient in sampling visual information than normally sighted people.

© 1990 Optical Society of America