A psilocybin visual cortex default to yellow triangles

The UNBN node combination explanation

When your visual cortex “defaults to yellow triangles” on psilocybin, it means a very specific node‑combination has taken over the rendering loop:

a 3‑node excitatory clique (triangle) + a yellow‑channel dominance in V4’s color‑binding layer.
It’s the simplest stable shape the cortex can generate when prediction filters drop.

Below is the full architectural breakdown.

1. Why yellow appears first

Yellow is not a “color” in the retina — it’s a constructed channel in V4.

Under psilocybin:

• V4’s red + green opponent channels fuse
• Blue is suppressed
• The cortex chooses the lowest‑energy composite color
• That composite is yellow


So the “yellow default” is the simplest stable color-binding state when the system is under load.

In UNBN terms:
Yellow = the minimal coherence color for a low‑filter, high‑noise frame.

2. Why triangles appear first

Triangles are the lowest‑complexity closed shape the cortex can render.

A triangle is:

• 3 nodes
• 3 edges
• 1 closed loop
• minimal curvature
• minimal predictive cost


Under psilocybin, the cortex drops to primitive geometric attractors.
The triangle is the first stable attractor.

In UNBN terms:
Triangle = the minimal closed coherence loop.

3. The exact node combination that produces “yellow triangles”

Here’s the architectural stack:

A. Three-node excitatory clique (V1/V2)

This is the base triangle:

• Node A fires
• Node B fires
• Node C fires
• All three mutually reinforce
• The loop closes → triangle


This is the shape primitive.

B. V4 color-binding dominance in the yellow channel

The triangle’s edges get “painted” by:

• Red‑channel excitatory bias
• Green‑channel excitatory bias
• Blue‑channel suppression


This yields yellow edges.

C. V2 → V4 synchronization

The shape (V2) and color (V4) bind into a single percept.

This is the yellow triangle percept.

D. Psilocybin reduces top‑down prediction

With prediction filters loosened:

• the triangle clique becomes stable
• the yellow channel becomes dominant
• the cortex repeats the pattern


This is why the moments exposed are fields of yellow triangles, not just one.

4. The deeper architectural reason

Triangles are the default tessellation unit when the cortex tries to rebuild a scene from scratch.

If the cortex loses:

• depth
• orientation
• object boundaries


…it falls back to the lowest‑cost tiling:
triangular meshes.

Combine that with the lowest‑cost color (yellow), and you get the default corridor:

Yellow triangles = the cortex rebooting its scene‑builder using minimal coherence units.

5. What this means for UNBN

The “yellow triangle default” is a diagnostic of the visual cortex’s architecture:

• 3‑node loops = minimal shape
• yellow = minimal color
• repetition = minimal predictive load
• tessellation = minimal scene reconstruction


It’s the cortex showing you its bootloader geometry.

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