A person with common red green colour blindness has difficulty distinguishing between which pair of colours?

Introduction / Context:

This question belongs to human physiology and vision. Colour blindness is a defect of colour perception in the eyes, usually caused by problems with cone cells in the retina. The most common type of colour blindness is red green colour blindness. Understanding which colours are confused helps in recognising the condition and designing accessible educational material and warning signs.

Given Data / Assumptions:

• The question refers specifically to colour blindness, not complete absence of vision.
• Common human colour blindness types include red green and blue yellow deficiencies.
• Red green colour blindness is by far the most frequent form, especially in men.
• We assume the standard description where people have difficulty distinguishing reds and greens.

Concept / Approach:

Normal human colour vision relies on three types of cones sensitive to different ranges of wavelengths roughly corresponding to red, green and blue. In red green colour blindness, one of the red or green cone types is absent or not functioning properly. This leads to confusion between colours that contain red and green components. The approach is to recall which pair of colours people with this condition typically cannot distinguish well.

Step-by-Step Solution:

Verification / Alternative check:

Medical and biology textbooks describe red green colour blindness as a sex linked condition often due to defects in genes on the X chromosome. They explain that affected individuals have trouble telling apart shades of red, green, brown and orange because of overlapping or missing cone sensitivities. Figures often show that reds may look more like browns or dark yellows, and greens may appear faded. These explanations confirm that the central problem is distinguishing red from green rather than the other pairs listed.

Why Other Options Are Wrong:

Black and yellow are very different in both brightness and colour, and even colour blind individuals can usually differentiate them. Yellow and white differ in brightness and saturation, and again are relatively easy to separate visually. Green and blue confusion can exist in certain specific types of colour vision deficiency, but the most common and classic form is red green, not green blue. Red and blue are also typically recognisable as distinct because blue uses a different cone type. Therefore, these options do not correspond to the main difficulty in common red green colour blindness.

Common Pitfalls:

Some learners assume that colour blind people cannot see any colours or confuse all colours equally, which is not accurate. Others may guess green and blue because they associate cool colours together. The key is to remember that most colour blindness cases are related to genes affecting red and green cones, making these two colours hardest to distinguish. This specific knowledge helps in answering related questions correctly.

Final Answer:

A person with common red green colour blindness cannot easily distinguish between Red and green.