Central Vision

Figure 10.5 shows a cross-section of a human eye. The incoming light is focused by the lens and falls onto the retina that lines the back of the eye. Different parts of the retina have different types of light-sensitive cells on them. In the central section

TABLE 10.5

Coloured Light on Different Coloured Surfaces

surface/

Ught

Colour

Red

Blue

Green

Yellow

Red

Bright red

Bluish red

Yellow-red

Light red

Blue

Red-purple

Bright blue

Dark green-blue

Reddish purple

Green

Olive green

Green-blue

Bright green

Yellow-green

Yellow

Red-orange

Reddish brown

Greenish yellow

Bright orange

Brown

Brown-red

Blue-brown

Dark olive brown

Brownish orange

Source: Modified from Woodson (1981).

Central Vision

FIGURE 10.4 Relative sensitivity of the eye for different wavelengths of light.

Central Vision

FIGURE 10.5 Cross-section of the human eye.

(fovea) are cones (see Figure 10.6), which are less sensitive to light. The cones are used for detailed imaging, and have a very different ability to distinguish detail from the rods that are found more peripherally around the retina; the rods are considerably more sensitive to light. The rods are used mainly for night vision and the cones for daylight vision. The cones help us distinguish colour.