Mary's grandmother, Pearl, is from the Old Country. Although she knows some English, she continues to speak her native tongue. Pearl can't go anywhere without a member of the family because she can't communicate with people about prices, directions, bus routes, etc.
Mary decides to try to modify Pearl's behavior. She and the rest of the family refuse to respond to any comment or request by Pearl that they know she is capable of expressing in English. For example, if during dinner she says, "Pass the potatoes" in English, she gets potatoes; if she says it in her native language she gets ignored.
Refer to Pearl. The procedure being used to change Pearl's behavior is