Answer to Question 1
According to the functional equivalence hypothesis, although visual imagery is not identical to visual perception, it is functionally equivalent to it. Functionally equivalent things are strongly analogous to each otherthey can accomplish the same goals. The functionally equivalent images are thus analogous to the physical percepts they represent. This view essentially suggests that we use images rather than propositions in knowledge representation for concrete objects that can be pictured in the mind.
Evidence for functional equivalence can be found in neuroimaging studies. In one study, for example, participants either viewed or imagined an image. Activation of similar brain areas was noted, in particular, in the frontal and parietal regions. Additionally, imagery can evoke responses in high-level visual brain areas and the visual primary cortexareas that are highly involved in the processing of visual stimuli we see with our eyes.
Answer to Question 2
To describe a picture in which a cat is sitting underneath a table, you could say, The table is above the cat.. You also could say, The cat is beneath the table.. Both of these statements indicate the same relationship as above the cat is the table.. With a little extra work, you probably could come up with a dozen or more ways of verbally representing this relationship. Logicians have devised a shorthand means, called predicate calculus, to express the underlying meaning of a relationship. This method attempts to strip away the various superficial differences in the ways we describe the deeper meaning of a proposition: Relationship between elements(Subject element, Object element)