Seeing is a skill, not a passive recording

Horowitz opens by rejecting the intuitive idea that the eyes work like a video camera, capturing an objective feed of the world that the brain simply plays back. In reality, attention is a bottleneck: the visual field contains far more information than any brain can process, so the mind constantly discards, compresses, and prioritizes based on what it has learned matters. Most of what passes in front of our eyes never registers as a memory or even a conscious percept at all.

This means two people occupying the same physical space are not having the same visual experience — they are each running a different, trained filter over an identical scene. A block that looks blank and uneventful to one walker might be dense with legible information to another, not because the second person has better eyes, but because their filter has been calibrated differently.

Takeaway: what you notice is a product of training, not just optics — which means it can be deliberately expanded.