Three-year-old emily spends every day with a therapist. her therapist her learn language and social skills by reinforcing positive behaviors. emily's therapist is using to treat her

I believe the answer is:  applied behavior analysis; autism

 applied behavior analysis is being done by creating a specific measurement for every actions that carried out by the patients.
Since the way autistic patient communicates tend to be different than normal people, it is importent for the therapists to teach the patient to learn basic communication and social skills.