Point of View: What Can Be Seen?
by Elizabeth Sinclair
Copyright 1996-1999
        The POV character's perception (what he can see) of a scene takes in his peripheral vision (anything he can see without turning his head). As soon as he moves his head, the vision loses some things but picks up others. For our purposes, we re going to assume that our character cannot turn his head.

POV Characters CAN:

Smell anything within smelling range of him
Touch anything within touching range of him
Hear any sound within hearing range of him
See anything within vision range of him (Note here that he must be facing the object or person to see it)
Taste anything within tasting range of him
He can feel his own emotions
He can think his own thoughts

POV Characters CANNOT: (Paranormal and Fantasy are the exception to this rule)

Feel the emotions of anyone else in the scene
Hear the thoughts of anyone else in the scene (He can ASSUME certain things about the above from body language, facial expression, or attitude)
See anything that isn't within his range of vision, which includes: His hair coloring, length, style or neatness
His eye coloring, including lashes and eyebrows
His facial expressions
His fullness of mouth or lips thinned in anger or in smile (These things will ONLY be visible to him, if he is looking at his reflection)
Or anything behind him or to the side that is out of his range of vision - unless he turns
Head-hopping is intrusive to the reader and interrupts their quest to get "close" to the characters.
If you're left with a stranger for five minutes, how much will you know about them, as compared to spending an hour with them? A day? The longer your reader is allowed to stay inside a character's head, the better they'll get to know them.

And, the better the reader knows the characters the more sympathy they'll feel for them. Also, don't overlook the fact that the longer you stay inside a character's head, the better you'll get to know them, too. And the stronger you'll be able to write them. Can you write effectively about a person you don't know? The answer to that is by the same token, readers can't care about strangers.