Simple Stimuli Trigger Fixed Behaviors

From site:  Consider what it would feel like to hatch out of your shell, look out on the world with your herring gull eyes and feel some pangs of hunger.  Because you haven’t learned much yet, you must rely on instinctive behavior in order to eat.  You look up at the large bird hovering over you, and you notice it has a large bill with a striking red dot on it.  Something about the dot compels you to peck at it.  You peck and peck and then your parent regurgitates its last meal and feeds it to you. 

The begging behavior is called a fixed behavior.  The fixed behavior typically occurs in response to a simple stimulus, such as the red dot on the parent’s bill.  Fixed behaviors lead to predictable responses and are important because they allow organisms to behavior appropriately even with limited experience.