A 22-year-old woman is seeing the PMHNP for the second time this week. At her last visit, she told the nurse practitioner she was the "best therapist in the whole world!" This week, however, the client says the PMHNP is "seriously the most horrible therapist in the universe." The patient talks in extremes and seems to see the world in black and white. Which modality helps clients understand that two opposing ideas can both be true?