10. Reflex and instinctive movements
1. The reflex
They are quick and unconscious movements in response to a stimulus. For example: the cat's pupils dilate when it gets dark. On the contrary, the pupils contract when the cat goes from a dark room to an iluminated room.
In the same way, these movements of contraction and dilation occur in human eyes.
The characteristics of the reflex are: son:
a) Unconscious since the will or intelligence are not involved.
b) Innate because they have not been learned by practice, but they were born with the person.
c) Useful because they help to the body's defense.
The spinal cord consists of nerves that regularize reflexes. The nerve conduction goes from the sensory nerve to the spinal cord and then it is "reflected" in the muscles that execute movements.
The conditioned reflex movement occurs in response to an stimulus associated with a natural and proper stimulus.
In natural way, the food in the mouth causes the salivary secretion. If the dogs are fed every time a whistle blows, there comes a time when dogs secrete saliva when they hear the whistle. This reflex is conditioned.
It also happens when men see a dish well presented: "the mouth will water."