The perceptual threshold for vision is defined as the ability to detect a(n) ________ located _________ on a clear night.
A) candle flame; 1 mile away
B) car headlight; 1 mile away
C) emergency flare; 30 miles away
D) candle flame; 30 miles away
E) camp fire; 8 miles away

Question

Quizplus · Accepted Answer

The perceptual threshold for vision, under ideal conditions, is often cited as the ability to detect a candle flame 30 miles away on a clear night. This demonstrates the sensitivity of human vision to small sources of light over long distances when conditions are optimal.

The Perceptual Threshold for Vision Is Defined as the Ability