Individuals struggling with sensory processing disorder (SPD), a neurological disorder that affects the proper processing of environmental stimuli, have trouble functioning when presented with seemingly benign daily interactions with his/her surrounding environment. For example, typically normal occurrences, such as a loud car horn or blinking streetlight may not be processed accurately, or elicit an unusual reaction by a person with sensory processing disorder.
Hyposensitivity occurs when a child is underwhelmed by the world around him or her and needs to seek out additional sensory information to feel content. Signs of this behavior could include a need to touch things excessively, always turning the volume very loud, or constantly putting objects in his or her mouth. Those who struggle with staying still for any extended period could be hyposensitive, trying to constantly seek movement stimulation.
On the contrary, hypersensitivity (also known as sensory defectiveness) is characterized by those who become uncomfortable when experiencing minor encounters with environmental stimuli. A person with hypersensitivity may smell scents others cannot detect, get distracted by common sounds, such as a humming refrigerator, or avoid using playground equipment in fear of different movements.