Cone vision operates under what lighting conditions and how does brightness affect visual acuity?

• A. Under normal lighting; visual acuity drops as brightness decreases
• B. Under dim lighting
• C. In infrared
• D. Under bright sunlight; acuity increases

Answer: (A)

Cone vision is the photopic, daylight system that uses cones to provide sharp, detailed, and color vision in well-lit conditions. Because cones require sufficient light to function effectively, visual acuity is highest under normal or bright lighting. As brightness decreases, cone performance diminishes and acuity drops; in dim conditions, rod vision takes over and, while more sensitive, produces much lower spatial resolution, making details blur. So the statement that cone vision operates under normal lighting and that acuity declines as brightness falls correctly describes how brightness affects visual sharpness.