Assymetry of the frame: cultural implications?

According to Zettl's Sight, Sound, Motion, 4/e pp. 109-10, "We do not seem to look at the left and the right sides of any screen in the same way, nor do we pay equal attention to objects on either half of the screen."

Zettl goes on to explain that we tend to read screens from left to right and thus a diagonal from lower-left to upper right looks "uphill" while a diagonal from upper-left to lower-right looks "downhill."

It's true. I see it that way too on the page.

Questions:

• Does this have a cultural or a linguistic basis?
• What about people raised with languages that go from left to right such as Hebrew or in vertical columns such as Chinese or Korean? Do they see the right-screen/left-screen effect in the same way?
• If this reality is different based on different linguistic traditions, would it be visible in the cinema of these traditions?