Sensation and behaviour
Our senses are the means by which we experience the world; everything we learn is detected by sense organs and transmitted to our brains by sensory nerves. Without sensory input, a human brain would be utterly useless; it would learn nothing, think no thoughts, have no experiences and control no behaviours.
Vision, to most people, is the most important sense modality. Through it we recognise family and friends, see their facial expressions and gestures, learn to read, perceive objects that are beyond our reach and find our way around our environment. It provides us with information about the size, shape, colour and movement of objects nearby and at a distance. Through vision, we receive some of our most powerful aesthetic experiences, in the form of art, a sexual partner and other beautiful images.
The other senses also contribute to the richness of experience. Because of the role that speech plays in human culture, audition is important for social behaviour and communication. Audition and vision provide information about distant events, as does the sense of smell, which can tell us about sources of aromatic molecules before we can see or hear that source. The other senses deal with immediate and proximal events such as the taste of our favourite food or the touch of someone we love. The body senses are closely tied to our own movements. When we feel an object, the experience is active, not passive; we move our hands over it to determine its shape, texture and temperature.