According to Weber's Fraction, which visual system is more sensitive to contrast?

The correct answer is based on the inherent characteristics of the visual systems governed by photoreceptors in the retina. The photopic system, which relies on cone photoreceptors, is responsible for vision under well-lit conditions and is particularly sensitive to color and fine detail. It is more adept at detecting contrasted images because the cones are optimized for high acuity and can discern subtle differences in light levels.

Weber's Fraction describes the relationship between the just noticeable difference (JND) in stimuli and the intensity of the stimulus. In the context of visual perception, a lower Weber's Fraction indicates a higher sensitivity to contrast. The photopic system typically has a lower Weber's Fraction than the scotopic system, suggesting it can detect smaller changes in contrast more effectively in brighter conditions.

On the other hand, the scotopic system, which uses rod photoreceptors, is more sensitive in low-light conditions but does not provide the same level of contrast sensitivity as the photopic system in brighter environments. While it excels at detecting motion and general shapes, it lacks the same ability to discern fine differences in contrast as the photopic system.

In summary, the photopic system is characterized by greater sensitivity to contrast due to its specialized function and structure, particularly in