You are currently in your calculus class, and you are concentrating solely on the information your professor is teaching you. Suddenly a loud, banging noise disrupts your once undivided attention. After looking up at the sound of the banging, you see that it is only a worker hammering as he installs a new bulletin board in the hallway. You would likely return your attention to the calculus lecture. If the banging noise continues, your tendency to look up at the noise in the hallway would steadily decrease. This decrease is called habituation. Habituation occurs solely on instinct for safety among humans and animals. This natural event includes the orienting reflex, habituation itself, and dishabituation.
Habituation begins with an orienting reflex. Orienting reflexes occur when we stop what we are doing to orient our senses in the direction of an unexpected disturbance. In the example, the orienting reflex is your first reaction to the noise. If you are like most people, you would immediately stop listening to the lecture and turn your head in the direction of the noise. What is the benefit of automatically paying attention to the disturbance? Self-protection would be the answer. Orienting reflexes allow us to evaluate our environments for potential harm.
The benefit of having orienting reflexes is limited, though. Your orienting reflex diminishes over time. After you have established that the noise in the hallway is not threatening, there is no reason to keep looking up and habituation occurs. If your orienting reflex continued, you would miss part of your calculus lecture as well as waste energy that could be spent more usefully. To get a feel for the value of habituation, imagine what life would be like if you could not habituate. Without habituation, you would reflexively respond to every sight, sound, touch, and smell you encountered every time you encountered it.
You can also stop habituating in certain circumstances. This is called...