How can you know what a state is like before you experience it?
Levels of sensory acuity are also like that.
For instance, your finger tips can be trained to distinguish the subtleties of braille, but before you acquired your discerning ability, your fingertips only experienced a grosser touch.
When your touch becomes acute, you can remember what it was like before and the difference between then and now.
The same with your visualizing acuity as it improves.
You can grossly imagine something or get so acute that you can do mathematics or play chess in your head.
What can you imagine in your mind's eye?
How about a color beyond the range of human perception?
How about a sound beyond the range of human hearing?
Now let's expand your imagination through the following exercise: (Visual) Imagine -- the color of a red apple.
-- the shape of a star.
-- the flashing of a green strobe light.
-- the number 7 on a blackboard changing into a 3- dimensional lion leaping from the blackboard.
(Auditory) Imagine -- the call of a duck.
-- the whistle of a train.
-- the laughter of children playing.
-- the din of a fog horn changing to the roar of a low flying jet overhead.
(Tactile) Imagine -- the stroking of a cat.
-- the tightness of grasping hands.
-- the roughness of sandpaper.
-- the warmth of warm water on your hands changing to snow flakes hitting your hands and melting.
(Gustatory) Imagine -- the taste of chocolate ice cream.
-- the carbonated flavor of a soda.
-- the bitterness of strong black coffee.
-- the crisp savor of an apple as you bite into it changing to a wax apple bitten into.
(Olfactory) Imagine -- the odor of gasoline.
-- the freshness of mint.
-- the aroma of freshly cut sawdust.
-- the fragrance of fresh baked bread changing to a rotten meat odor.
(Kinesthetic) Imagine -- the feeling of jogging.
-- the balance of tight rope walking.
-- the gracefulness of waltzing.
-- the movement of skiing changing into a free fall and parachuting as you ski off a cliff.
Now alternate with a partner on other visualized sensations.
You create one for your partner to visualize; then your partner creates one for you to visualize, and so on.