Distance discrimination in a simulated space environment

The just noticeable difference (JND) for distance was investigated by a paired-comparisons method using successive comparisons. The research utilized an optically simulated large target located in a textureless environment at distances along the saggital plane out to 12, 800 ft. The value of ΔD/D varied from less than 3% at 200 ft to about 7% at 12, 800 ft. The results confirmed a power function relationship between distance threshold and observation distance.