Vision beyond the visible spectrum

The claim that 1% of people see infrared and 1% see ultraviolet has no reliable support. Under ordinary conditions, human eyes see only the visible part of the spectrum. There are exceptions: people without a natural lens can perceive some near-UV, and pulsed near-IR has been detected in specialized laboratory experiments through a two-photon process. These findings do not establish population percentages. The illustration is an AI-generated synthetic diagram.