Are dermatillomania and trichotillomania linked to Si ego types? From experience alone, I believe they might be.
Excoriation disorder is defined as "repetitive and compulsive picking of skin which results in tissue damage". Its most official name had been "dermatillomania"
A pair of studies published in 2017 and 2018 were the first to report that individuals with BFRBs have higher rates of sensory over-responsivity to external sensations than the general population. In other words, they respond intensely to things like sounds and textures.“It would appear that pulling might therefore be an external attempt on the part of a genetically prone individual to regulate an internal state of sensory imbalance,” he writes.
According to this model, a person with a BFRB is exposed to the same levels of environmental stimulation as others, but their nervous system is unable to easily manage it. “It is as if the person is standing in the centre of a seesaw, or on a high-wire, with overstimulation on one side, and understimulation on the other, and must lean in either direction (by pulling) at different times, to remain balanced,” he writes.
On that thought, I’ll say Si could also be involved in the development of more temporary afflictions such as pica as well as in habits like rubbing certain fabrics repeatedly. An offshoot from the same inclination: petting cats or dogs in a special way (and often intrusively) because of an obsession with their fur (poor souls).