Ethnocentrism, a term coined by social evolutionist William G. Sumner in 1906, is generally defined as "the belief in one's own ethnic group's superiority".
Ethnocentrism is generally defined as "the belief that one's own native culture is the most natural or superior way of understanding the world". It's the tendency to look at the world primarily from the perspective of one's own culture.
It can be prejudicial attitudes towards the other by not accepting their different cultural values and beliefs. It's a belief in the centrality of one's own culture. It's a judgment of another culture by the standards of one's own.
"This tendency to view the Other from the perspective of one's own is often accompanied 1) by feelings of dislike for other groups or cultures, 2) by judging other cultures solely by the values and standards of one's own culture, 3) judge other groups relative to his or her own particular ethnic group or culture, especially with concern to language, behavior, customs, and heritage."
Deaf people speak a different language in a different modality. Deaf people are a cultural-lingual group and don't consider themselves as a disability group typically as seen by hearing people. Disability is a social construction defined within the phonocentric society. Hearing people don't realize that they do have a 'hearing culture' recognized and defined by Deaf people.
This leads to a number of -isms within the hearing world: phonocentrism, audism, ethnocentrism, linguicism, and so on. These -isms have been around for over thousands of years.
When studying ASL/Deaf culture and language, it is important to examine one's beliefs and attitudes regarding another culture.
Look at Janet Bennett and Milton Bennett (1993) 's work on the development of intercultural sensitivity:
Denial | Defense | Minimalization | Acceptance | Adaptation | Integration
The first three stages are ethnicentric stages and the last three are the ethnorelative stages from the monocultural mindset to the intercultural mindset.
First experience is failing to perceive the existence of culture. Little understanding. Refusal to recognize a culture. E.g. "Deaf culture is not important!" "There is no such as Deaf culture."
Perceiving us vs them. E.g. "Deaf people should learn how to vocally-speak." "All Deaf people are the same."
De-emphasizing difference. Focusing on shared human experience and universal values to reduce prejudice.
Recognizing different cultural groups and identities and accepting cultural differences. E.g. Curious students take ASL courses to learn about the signed language and Deaf culture.
Ability to make appropriate behavior with more cultural sensitivity and awareness. E.g. ASL students turn off their voice in Deaf space.
Including multicultural viewpoints.
You may also be interested in: phonocentrism.