MCQ Detailed View

When we close our eyes in the dark, many people assume that what we see is pure black. However, in reality, the visual sensation is not perfect blackness but a special shade of dark gray called eigengrau (German for “intrinsic gray”).

Eigengrau is the natural dark gray background color that the human visual system perceives in the absence of light. It occurs because of the spontaneous activity of photoreceptor cells (rods and cones) in the retina. Even when no external light enters the eyes, these cells continue to fire weak signals to the brain. As a result, our brain interprets this internal activity as a dim grayish background rather than absolute black.

This phenomenon highlights an important fact: our visual perception is not just a direct response to external light but also influenced by internal neurological processes.

Key scientific points:

1. 
   

   Not Absolute Black – True black is the complete absence of light. However, our eyes never perceive total darkness due to retinal activity.

   
   


2. 
   

   Retinal Noise – Photoreceptors are constantly active, sending signals to the brain, which the brain interprets as a grayish visual field.

   
   


3. 
   

   Eigengrau – Also known as “dark light” or “brain gray,” eigengrau is the scientific term for this perception.

   
   


4. 
   

   Psychological Effect – This is why even in a pitch-dark room, people still “see” something, usually a grayish fog or tiny flickering patterns.

   
   


5. 
   

   Practical Insight – This concept is used in neuroscience and psychology to explain how our senses are influenced by both external stimuli and internal activity.

   
   

Therefore, the correct answer is Eigengrau, not black, because the brain and eyes never truly go dark.

✅ Correct Answer: Eigengrau