What is hallucinations?

Whatever we perceive is not always real. For actually it is an illusion. Evan our sense of balance can be deceived. Hallucinations often occur because things do not happen the way we expect them to, and the brain gets 'confused'.

How does the eye work?

We can think of the eye as a kind of camera. The iris behind the cornea is light sensitive and corresponds to the aperture of the camera. This can be set near or far, depending on the amount of light falling on it. The light rays penetrate the lens of the eye, and fall on the retina. Millions of light-sensitive cells convert the light into signals sent to the brain via the optic nerve. These are put together to make images,and are interpreted by the brain. There are two types of cells in the retina: the light-sensitive rods that help us see in the dark and the less sensitive cones that help us see colours.

Why is the sense of touch important?

Without the sense of touch we would be quite helpless. We would not be able to feel oneself, we would not feel our feet hitting the floor while walking and injuries would go unnoticed because no pain would be felt. We would also be deprived of many pleasant experience important for social interaction. For blind people the sense of touch is very important. They move around safely by feeling and touching objects in their surroundings. Blind people compensate for their lack of sight by highly development sense of touch.