University Medical Center – In low light, our eyes and brain conspire to create illusions — flickers of movement, faint colours, and shadowy figures that seem to lurk just beyond sight. According to Dr.
Scott E. Brodie, professor of clinical ophthalmology at Columbia University Medical Center, these sensations emerge from how the visual system adapts to darkness.
The combination of reduced visibility, heightened awareness, and an active imagination can evoke primal fear responses. It’s the same psychological mechanism that makes horror films like The Blair Witch Project so effective — tapping into our innate unease about what lies hidden in the dark.
Through minimal visuals and suggestion, the film becomes a study in absence, perception, and the terrifying power of the unseen. Not Everything You See Is Real We like to think our vision provides a faithful snapshot of reality — but it doesn’t.
As Dr. Brodie explains, our visual system can be deceived by neurological and biochemical processes. Optical illusions vividly demonstrate this: they expose how easily the brain can reinterpret — or misinterpret — visual signals.
Story continues below this ad German vision scientist Michael Bach has catalogued numerous such illusions, revealing how perception can bend, twist, and invent images that don’t objectively exist. A simple way to witness this distortion is by gently pressing on the upper part of your closed eye. As you move your finger, you’ll notice a bright-rimmed black circle that seems to drift in the opposite direction.
No external light is involved — the effect arises from mechanical stimulation of the retina, prompting nerve cells to fire and the brain to generate a visual image. This phenomenon is known as phosphenes, from the Greek for “light” and “to show.
” Phosphenes can result from mechanical pressure, electrical stimulation, or even trauma — like the flashes of light some people see after bumping their head. In each case, the brain creates the experience of light where none exists, blurring the boundary between perception and imagination. Seeing in the Dark Even in near-total darkness, your eyes remain active.
The rod cells in the retina — highly sensitive photoreceptors concentrated along its edges — become dominant, enhancing peripheral vision. Story continues below this ad Dr.
Brodie notes that retinal activity in darkness remains comparable to that in bright light, though it’s primarily driven by “off cells” rather than “on cells. ” Tiny fluctuations in these signals can trigger the retinal circuitry, generating the illusion of sight even without light input. On a neurological level, this is linked to closed-eye visualizations (CEVs) — spontaneous images or colors that appear behind closed eyelids.
These internal “hallucinations” emerge naturally, without any mechanical pressure or external stimulation. Why We Never See Pure Black When you close your eyes or sit in a pitch-black room, you don’t actually see black — you see a murky, shifting grey. This color is known as eigengrau, or “intrinsic grey,” a term coined by physicist Gustav Fechner in the 19th century during his studies of visual perception.
Eigengrau results from visual noise — random signals generated by the optic nerve that the brain interprets as faint light. In complete darkness, these signals dominate, preventing us from ever perceiving a truly black void.
Story continues below this ad Brodie emphasizes that this noise, combined with heightened sensory awareness in the dark, explains why we feel more alert when visibility is low. Our auditory sense sharpens, our body awareness (proprioception) intensifies, and our brain becomes more vigilant — a primal adaptation for survival.
The Darkness Within What we perceive in darkness is not the absence of vision but the presence of the brain’s own light — the flickering echoes of neural activity and imagination. In the void, our mind fills in what the eyes cannot see, turning darkness into a canvas of perception, fear, and wonder.