Three cone types: which is correct?

Three cone types: which is correct?

• A. S-cones around 450 nm; M around 534-545 nm; L around 564-580 nm.
• B. S-cones around 420 nm; M around 534-545 nm; L around 564-580 nm.
• C. S-cones around 600 nm; M around 520 nm; L around 440 nm.
• D. S-cones around 350 nm; M around 700 nm; L around 900 nm.

Answer: (B)

The idea being tested is how the three cone types are each most responsive to different parts of the visible spectrum, forming the basis for color vision. S-cones (blue) are most sensitive in the short-wavelength blue region, with a peak around 420 nm. M-cones (green) peak in the mid-wavelength green region, about 534–545 nm. L-cones (red) peak in the longer-wavelength red region, roughly 564–580 nm. These peak values are the ones that best match the classic descriptions of cone sensitivities. The option that lists S-cones near 420 nm, M-cones near 534–545 nm, and L-cones near 564–580 nm aligns with widely established measurements of cone spectral sensitivities. The other options place the blue cone peak at incorrect wavelengths (too far into the blue or toward red/ultraviolet ranges) or swap/misplace the red and green peaks, which doesn’t fit how the three cones are tuned. The reason this matters is that the brain distinguishes colors by comparing the relative activation of these three cone types across the spectrum.

The idea being tested is how the three cone types are each most responsive to different parts of the visible spectrum, forming the basis for color vision. S-cones (blue) are most sensitive in the short-wavelength blue region, with a peak around 420 nm. M-cones (green) peak in the mid-wavelength green region, about 534–545 nm. L-cones (red) peak in the longer-wavelength red region, roughly 564–580 nm. These peak values are the ones that best match the classic descriptions of cone sensitivities.

The option that lists S-cones near 420 nm, M-cones near 534–545 nm, and L-cones near 564–580 nm aligns with widely established measurements of cone spectral sensitivities. The other options place the blue cone peak at incorrect wavelengths (too far into the blue or toward red/ultraviolet ranges) or swap/misplace the red and green peaks, which doesn’t fit how the three cones are tuned. The reason this matters is that the brain distinguishes colors by comparing the relative activation of these three cone types across the spectrum.