Visual accommodation and virtual image displays: Target detection and recognition

Twelve subjects performed a complex task, detecting and recognizing small targets presented at infinity, while simultaneously monitoring a virtual image display (VID). The VID was presented at one of four optical distances (2.0, 0.5, 0.0, and- 0.5 D). Optical distance was found to affect detection and recognition performance, mainly at the extreme value of 2.0 D. Interactions between optical distance and grouping of subjects according to measures of accommodation indicated that the three other optical distances affect performance differen-tially. The subjects ' resting position of accommodation (RPA) and a combined measure of accommodation range and RPA were significantly correlated with performance (0.58). A narrowing of the functional visual field (complete misses of peripheral targets) was found at the 2.0-D optical distance for all subjects, and at the other optical distances for the subjects with an inferior accommodative mechanism (i.e., a near RPA and/or a narrowaccommoda-tion range)