The 8 (eight?!?) senses: Occupational Therapy and Sensation

We all learned about the basic five senses in grammar school - sight, sound, taste, touch and smell - but did you know there were thee more? Here an Occupational Therapist outlines the sensational frontier.

We all utilize our senses everyday. We often take them for granted. But what if we thought more deeply about them? Or what if one didn't work as it does for many other people? These are some of the questions that Occupational Therapists working with Sensory Integration - the ability of the central nervous system to process information to make an adaptive response to the environment (1) - think about when working with their clients. Outlined below are the classic five senses we often think of - plus three more that many of us are unfamiliar with yet impact our everyday lives under the surface.

Vision: We use visual information to help alert and calm ourselves and to focus and attend.

Auditory/Hearing: This is how our brain registers sounds in order to analyze them and produce a response. Our auditory system alerts us to sounds so that we can draw our attention to what is necessary.

Tactile/Touch*: Tactile receptors provide information regarding the location and kind of touch experienced on the surface of our skin. Light touch stimuli (such as tickling) is frequently alerting. A deep pressure stimulus (such as massage) is often calming and organizing. We have two ways of responding to sensory input from touch. The higher, more mature response is discrimination, which allows us to immediately interpret what the stimuli is and whether or not we need to respond to it. The more basic, survival-oriented response is a protective fight, flight or fright/freeze reaction.

Olfactory/Smell: This system is responsible for detecting different odors, discriminating between them, determining their importance and signaling to the brain about their significance. This processing is vital for detecting food, hazards and even social cues, and is closely linked to memory and taste.  

Gustatory/Taste: This system includes eating and being able to perceive various temperatures, textures and tastes of foods, working to keep us safe and even signaling when we need hydration. This sense can be helpful with self-regulation as your body receives oral input and stimulation (for example how it responds to chewing gum, drinking warm tea, etc.).

Proprioception: This is the body's response to changes in joint and muscle positions. Proprioceptors are receptors in the muscles and joints that provide information about where our bodies are in space. Accurate registration and interpretation of proprioceptive input is important for using our bodies skillfully. Proprioceptive input can increase body awareness and a sense of overall grounding.

Vestibular: This is the body's response to movement. Vestibular input is received through the semicircular canals in the ears and provides us information about our head position, coordinates our head and eye movements, contributes to underlying muscle tone and mediates our response to movement and gravity. This information also influences our alertness, activity level and attention. Vestibular input can vary in the intensity depending on the type of movement. Linear movement (back and forth or side to side) is the least stimulating. Rotary input (spinning, twirling, merry-go-round, etc.) would be more stimulating as the fluid within the semicircular canals would increase in movement. The most intense vestibular movement is head inversion such as somersaults, flips, etc. In this type of movement, the fluid moves throughout the entirety of the canals making the stimulation much greater.

Interoception: Interoception is the sense that allows us to experience sensations from inside our body. This can feel like a grumbling tummy when you are feeling hungry or your heart pounding after climbing up many flights of stairs. Interoceptors are internal receptors and sensors that detect stimuli and relay these signals to the brain via neural pathways, where they are then processed and interpreted. This relationship between the body and brain is not only one-way but rather a dialogue; the brain receives and also sends signals to modulate internal bodily states. These sensations can feel different for everyone yet are important to attune to as they provide important information about how we are feeling and what we need.

[*Our proprioceptive, vestibular and tactile systems work together to provide a foundation for the development of body awareness (body scheme), position in space, motor skills and contribute to an overall sense of organization and well-being in the world.]

For many of us, these senses work together as a symphony, combining to create a harmony that makes life a truly rich experience. But what if they sometime get off beat? Or can't sync up to begin with? This is where talking with an Occupational Therapist who is trained in Sensory Integration can be helpful.

1. Jacobs, K., & Jacobs, L. (Eds.). (2009). Quick reference dictionary for occupational therapy (English ed.). SLACK Incorporated.