Pica, according to the U.S. National Library of Medicine, is when an individual craves materials that can’t strictly be considered “food” for a period that’s longer than a month. This could include chalk, but also materials like clay, sand, dirt, glue, paper, and pretty much any other material you can imagine. It’s common in children, but it also occurs in teens and adults with unknown prevalence.
ASMR is usually precipitated by stimuli referred to as 'triggers'. ASMR triggers, which are most commonly auditory and visual, may be encountered through the interpersonal interactions of daily life. Additionally, ASMR is often triggered by exposure to specific audio and video. Such media may be specially made with the specific purpose of triggering ASMR or originally created for other purposes and later discovered to be effective as a trigger of the experience.