In "Mother Tongue," author Amy Tan describes a situation in which her mother, a non-English speaker, faces rude treatment from a doctor. This doctor is then polite to Tan, who speaks English without an accent. What phenomenon does the doctor demonstrate?

Language bias is the answer

i think the phenomenon that the doctor demonstrate is : language bias When the doctor heard someone talks without proper english, he treated her poorly. But when he faced someone that speaks proper english, he treated them nicely, which indicate that he had a bias toward the people that unable to speak his mother tounge