A 35-year-old woman with Borderline Personality Disorder is…

A 35-year-old woman with Borderline Personality Disorder is in therapy. She reports feeling empty and often engages in superficial cutting to “feel something.” During a session, she describes her new partner as “the most perfect person” she’s ever met, a stark contrast to the previous week when she described him as “a monster.” This rapid shifting between extremes is an example of what defense mechanism?