Tickle may also depend on nerve fibres associated with the sense of touch. However, in some patients that have lost pain sensation due to spinal cord injury, some aspects of the tickle response do remain. Further studies have discovered that when the pain nerves are severed by surgeons, in an effort to reduce intractable pain, the tickle response is also diminished. Zotterman found that the 'tickling' sensation depended, in part, on the nerves that generate pain. In 1939, Yngve Zotterman of the Karolinska Institute studied the knismesis type of tickle in cats, by measuring the action potentials generated in the nerve fibres while lightly stroking the skin with a piece of cotton wool. It appears that the tickle sensation involves signals from nerve fibres associated with both pain and touch.

A German study also indicates that the gargalesis type of tickle triggers a defense mechanism for humans in the hypothalamus conveying submissiveness or fleeing from danger. These reactions are thought to be limited to humans and other primates, although some research has indicated that rats can also be tickled in this way. Gargalesis reactions refer to a laughter-provoking feeling caused by a harsher, deeper pressure, stroked across the skin in various regions of the body. Horses also exhibit a response to knismesis, as they can be observed twitching the panniculus carnosus muscle in response to insects landing on their sides. This reflex can be brought on by actions such as scratching, brushing, stroking, or even tapping the sensitive area. When stimulated in the saddle region, most dogs will exhibit a reflexive rhythmic twitching of their hind legs. For example, a dog exhibiting the scratch reflex is an example of knismesis. This may explain why it has evolved in many animals.

Knismesis, also known as a 'moving itch', is a mildly annoying sensation caused by a light movement on the skin, such as from a crawling insect. The tickle can be divided into two separate categories of sensation, knismesis and gargalesis. Tickling results from a mild stimulation moving across the skin, and is associated with behaviors such as smiling, laughter, twitching, withdrawal and goose bumps.

Erotic Tickling by Michael Moran