It might be useful to consider for a moment how empirical research on the effects of television viewing is sometimes conducted. A university researcher persuades 40 undergraduate students from class to volunteer as research subjects. On a day and at a time predeterm ined by the researcher and anticipated for 2 weeks by the students, each subject travels to the research facility housed in an eight-story university build ing. The subjects get off the elevator and enter a room, 20 by 30 feet. The room is tiled in linoleum and illuminated by fluorescent lights. Arranged in the room are 40 stackable plastic chairs and a 23-inch color TV sitting atop a large mobile stand.