If a person is assaulted on the street of a large city in the middle of the day with many people around, the likelihood that someone will call for help will actually decrease in relation to the larger crowds. This phenomenon is known as which of the following?

Diana takes the subway to and from school every day. Her family’s apartment, situated in a low-income neighborhood of New York City, is a thirty-minute walk from the subway station. During her trips to the subway, Diana loves to watch people work, play, and socialize. She feels very safe in her community because she trusts the people around her.

Diana sees a large man yelling at a woman. He shoves the woman and she tries to run away, but the man grabs her. Even though she is yelling, none of the other pedestrians pay any attention. Which of the following social terms describes the scene that Diana is observing?