The size of the visual span is set at 9 characters, and a central scotoma of 1 to 7 characters is embedded within this visual span. Subjects make simulated saccades by pressing keys on an electronic piano keyboard. Each key represents a movement of an integer number of characters forward of backward in the text. The task of the human and ideal reader is to move through the text in the minimum number of saccades, identifying every word. Subjects are given as much time as they need to make their saccade decisions.
Preliminary results indicate that human readers can approach the performance of the ideal observer.
Given unlimited time for planning simulated saccades, human readers can integrate information across a central scotoma and approach the level of performance of an ideal observer. If readers are asked to perform the task more quickly, integration of information across a central scotoma becomes less likely. Supported by NIH Grant EY02934.