What causes tactile defensiveness?
As we discussed in our article on the touch system, there are three types of touch sensory inputs. These are light touch, discriminative touch and touch pressure. If you haven’t read this post, we recommend you read if first before reading any further. It will help with your understanding of tactile sensitivity.
You can also learn more about the touch system in our free course ‘Introduction to Sensory Processing.’
Types of touch
In addition to light touch, discriminative touch and touch pressure, the skin also receives information about pain, temperature and vibration. Light touch and pain typically warn the body about potential threats, so are often called ‘protective sensations’. They send sensory information through a different nerve pathway to the discriminative touch sensations. A nerve pathway is like a road that the sensory signals travel along to the brain. Usually, once these protective sensations warn the brain that something has touched the skin, the brain then receives extra information from the discriminative touch pathway to let it know what that something was.
For example, if you touch something hot, the brain will immediately acknowledge the feeling of pain. As a result, the brain will make the body move your hand away. Next, you will receive extra sensory information from the discriminatory touch pathway. This lets you know more about where the pain is and also that it feels like a burn. The brain receives different sensory information from each pathway.
As another example, if your hair is dangling in your face, the first time it touches your face you might get a surprise. You may not know exactly what the light touch sensation on your face was. However, extra information about that piece of hair will then go through the discriminatory touch pathway or you might brush your hand on your face and this will let the brain know it’s just a piece of hair. It is nothing to worry about and your brain will ignore it.
Sensory Integration – a theory behind tactile defensiveness
Jean Ayres thought tactile hypersensitivity occurs because the brain pays too much attention to light touch and protective sensations from the skin. Instead of listening to the extra information available from the discriminative pathway, the brain keeps paying attention to the light touch and protective sensations. These sensations are designed to alert the body to a problem or threat. They are designed to keep the body safe. So, each time the brain receives a message from these pathways it initially thinks that something might be wrong. It gets ready to protect the body. This is called a fight, flight or freeze response. Jean Ayres thought that the brains of children and adults with tactile defensiveness interpret ordinary touch sensations, such as clothing or a hug, as a threat. Their brains pay more attention to light touch sensations than the brains of children without touch sensitivity.
This helps to explain the behaviours that are seen in children or adults with tactile defensiveness. Their responses to everyday touch can often result in meltdowns, arguments and avoidance. This is because their brains are feeling that touch in the same way you might if you touched something hot or ran into a spider web. The everyday touch activates their brain’s protective system and triggers a fight, flight or freeze response. Some adults with touch sensitivity have also reported that certain everyday touch sensations feel painful.
Difficulty ignoring touch sensations
Children and adults who experience tactile sensitivity may also find it more difficult to ignore touch sensations. A comparison would be the feeling of having a stone in your shoe, a stone that is very annoying and constantly drawing your attention until you take off your shoe and remove it. For children or adults with tactile hypersensitivity, sometimes it is everyday touch that feels like the stone. This could be something like the tag on the back of their t-shirt, or the feel of a certain fabric. Their brains cannot ignore the feeling and they just need to get away from it, in the same way you want to remove the stone.