As we mature, our nervous systems develops based on our life experience and environmental demands. We adapt and maintain balance to these demands through three key processes; modulation, habituation and sensitization.

Modulation is the ability of the central nervous system (CNS) to monitor and regulate information received in order to generate appropriate responses (Dunn,1997b).

When modulation is intact the nervous system responds to some stimuli while ignoring other stimuli. This results in an appropriate response to the situation.

Modulation regulates habituation and sensitization responses.

We need habituation to focus our attention on the task at hand. Without habituation we would be distracted continually by all stimuli because our sensory system would keep interrupting us to notice each new thing that comes along. We would appear distractible, agitated, or inattentive.

Sensitization occurs when the system perceives sensations as unfamiliar or potentially harmful, causing a heighten response. Balance of these processes determines our ability to respond to stimuli from our surroundings.