Representational Illusion has a control simplification effect in a certain type of cognitive Architecture. By simplifying the perception, the number of interactions that have to be dealt with is reduced. The trick is to find a balance between the representations simplicity and the complexity of the environment within which the representation is made, so that the organism achieves control of their own survival.
Because the representation is simplified with respect to reality, it is partly an illusion. The nature of what is illusary and what is real is an architectural compromise defined by the nature of the way that representation becomes possible within the specific brain. This in turn would be different at least for every species.
One aspect of this is that the representation is highly individualistic, and is not shared between even members of the same species, although the mechanisms of perception are at least similar in basic architecture.