Iconicity is similarity or analogy between the form of a sign (linguistic or otherwise) and its meaning, as opposed to arbitrariness. The first studies on iconicity in ASL were published in the late 1970s, and early 1980s. Many early sign language linguists rejected the notion that iconicity was an important aspect of sign languages, considering most perceived iconicity to be extralinguistic. However, mimetic aspects of sign language (signs that imitate, mimic, or represent) are found in abundance across a wide variety of sign languages. For example, when deaf children learning sign language try to express something but do not know the associated sign, they will often invent an iconic sign that displays mimetic properties. Though it never disappears from a particular sign language, iconicity is gradually weakened as forms of sign languages become more customary and are subsequently grammaticized. As a form becomes more conventional, it becomes disseminated in a methodical way phonologically to the rest of the sign language community. Nancy Frishberg concluded that though originally present in many signs, iconicity is degraded over time through the application of natural grammatical processes.