Researchers have studied vision more thoroughly than the other
senses. Because people need sight to perform most daily activities, the sense of
sight has evolved to be highly sophisticated. Vision, however, would not exist
without the presence of light. Light is electromagnetic radiation that
travels in the form of waves. Light is emitted from the sun, stars, fire, and
lightbulbs. Most other objects just reflect light.
People experience light as having three features: color, brightness, and saturation. These three types of
experiences come from three corresponding characteristics of light waves:
- The color or hue of light depends on its wavelength, the
distance between the peaks of its waves.
- The brightness of light is related to intensity or the amount of light an
object emits or reflects. Brightness depends on light wave
amplitude, the height of light waves. Brightness is also somewhat
influenced by wavelength. Yellow light tends to look brighter than reds or
blues.
- Saturation or colorfulness depends on light complexity, the
range of wavelengths in light. The color of a single wavelength is pure spectral
color. Such lights are called fully saturated. Outside a laboratory, light is
rarely pure or of a single wavelength. Light is usually a mixture of several
different wavelengths. The greater number of spectral colors in a light, the
lower the saturation. Light of mixed wavelengths looks duller or paler than pure
light.
