Instinct is the inherent inclination of a living organism toward a particular behavior. Instinctual actions have no learning curve. They are hard-wired and ready to use without learning. Some instinctual behaviors depend on maturational processes to appear.
Immediate instinct, also known as imprinting, causes geese to follow around the first moving object that they encounter, as it tends to be their mother. A favorable trait, such as an instinct, can improve survival rate of life forms possessing the instinct.
Many scientists consider that it is instinctual in children to put everything in their mouths, because this is how they tell their immune system about the environment and the surroundings, and what the immune system should adapt to.
A displacement activity is a behavior that is the result of two contradicting instincts in a particular situation. A human may scratch its head when it does not know which of two options to choose. Similarly, a bird may peck at grass when uncertain whether to attack or flee from an opponent.