Sensory system

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An eye turns photons into nerve impulses: the brain's visual cortex turns the impulses into information which the brain can handle. Subjectively, we feel we see the world 'directly'. Actually, the brain has constructed what we see from data given to it by our eyes.

The sensory system is the way animals find out about their nearby environment. To do this they have special devices for collecting data called sense organs. The sense organs act as transducers: they turn energy from the outside into nerve impulses. The information which comes in is then very rapidly processed by the brain. The whole arrangement is the sensory system.

It is usual to say the sensory system has five senses:

  1. Hearing is the sense of sound. Ears hear sounds.
  2. Sight is the sense of seeing. Eyes see.
  3. Touch is the sense of feeling. End organs feel.
  4. Taste is the sense of the flavor. Tongues taste.
  5. Smell is the sense of scent. Noses smell.

Actually, there are other senses. We have a sense of proprioception which checks our balance. Fishes have a sense system which no land animal has.[1] It is called the lateral line system. This senses movement and vibration in the water pressure and other functions. Some fish can sense patterns of electrical current in the water.

Handling the data[change | change source]

A huge amount of data comes in from the sensory system. About 11 million pieces of information per second is one estimation, of which ten million comes from our eyes.[2] Of this huge number we only handle about 40 in our conscious mind. The rest is handled non-consciously.[3]

References[change | change source]

  1. Most amphibian larvae have a similar system.
  2. Wilson, Timothy D. 2002. Strangers to ourselves: discovering the adaptive unconscious. Harvard University Press. p24 ISBN 0-674-01362-4
  3. Norretanders T. 1998. The user illusion. transl. J. Sydenham. Viking, New York.