Question: what feautures do the eyes have

Andrew French answered on 17 Jun 2014:

Hi

Basically its like a camera. They have a lens to focus light, an aperture (small window which can change size) called the pupil which changes how much light can get in (its small in the sun to let in a small amount, and large at night to let in much more). This is the black bit in the middle of the eye. There is then the retina on the back of the eye, which is basically a load of cells which are sensitive to light – this is just like the sensor chip in your digital camera which also is sensitive to light, and builds up the “picture”.

There are also some cells which ‘process’ the outputs from these cells – as well as sending signals to the brain, some cells seem to be sensitive to ‘features’ we can see – features such as lines or corners. This is why looking at black and white stripy optical illusions sometimes looks a bit weird, because these cells get confused by the illusion. Exactly how these cells work and what they do is still an area of research though.