Certain processes, models, questions, and ideas are applied by the reader, resulting in improved clarity and comprehension. When a reader "skims" a text, the reader just sees the surface qualities and information.
Answer:
The word "protracted" means lasting longer than expected, or unusually long, so what protracted most clearly means based on the context of the excerpt is how the time period of celestial motion studies must have lasted unusually long.
Well behaviors are completely "involuntary" and reflect people's true states. Most people will only attempt to control their nonverbal behavior when they are lying.