He's been in their lives for over 10 years. But it goes on, and it will evolve.â. Indeed, Grey's has persevered after the departures of several regular cast members, including Isaiah Washington, Sandra Oh, Katherine Heigl, T.R. Knight, Kate Walsh, Eric Dane, Chyler Leigh, and Kim Raver.
1 Some state that the average human attention span is approximately 5 minutes; others state that most healthy teenagers and adults are unable to sustain attention on one thing for more than about 20 minutes at a time, although they can choose repeatedly to re-focus on the same thing.
Attention span is the amount of concentrated time one can spend on a task without becoming distracted. Most educators and psychologists agree that the ability to focus attention on a task is crucial for the achievement of one's goals.