What metaphors are used in True West by Sam Shepard?

In a 1980 interview with Robert Coe, Shepard said that in True West he "wanted to write a play about double nature, one that wouldn't be symbolic or metaphorical or any of that stuff. I just wanted to give a taste of what it feels like to be two-sided. It's a real thing, double nature. I think we're split in a much more devastating way than psychology can ever reveal.... It's something we've got to live with."

The interview was published in th New York Times.