The definition I’ve come across most often in non-academic journals (i.e., on the internet) is that nose-picking is the act of extracting dried nasal mucus (snot) and/or foreign bodies with a finger from the nose.
There have been anecdotal reports that people engaging in some sorts of activity appear to be more likely to pick their noses in seemingly public places (drivers stopping at traffic lights or junctions being one example I came across in a blog on nose-picking).
Early follow-up showed improvement” They noted that the psychiatric literature has recognized that “rhinotillexomania is a common, benign habit in children and adults” but that in rare cases it can become a serious affliction advancing to significant self-injury.
She could not control her compulsion, which involved removing recurrent intranasal crusts.
This condition persisted while in the care of a psychiatrist…
They also observed that based on their sample, nose-picking practices were the same across all social classes.
Much less is known about the act of eating the extracted contents directly from the nose (known as mucophagy).
I did a literature search looking for academic papers on snot eating snot and only came up with only one by Maria Jesus Portalain – a 2007 book chapter entitled “Eating snot – Socially unacceptable but common: Why?