Re: [gutvol-d] looking at the most meaningful indicator

The time I check a biology book the human has just one visual system.

The biology books lie, as do ophthalmologists and optometrists. How people read, and how they visually perceive varies greatly from person to person. As the very simplest, consider the wide variety of visual orthotics something more than half of all humans wear, and how varying various people's mental and emotional responses are to the same book -- the brain is part of the visual system.