A
theory that states that when a person
perceives an
object, the object of awareness is not the object itself, but a
sensory experience which
represents the object. The person is not
directly aware of
reality itself.
This argument is closely related to the theory of Immanuel Kant which states that there is a object which exists in itself, but human perception can not learn anything about it. Rather, humans can only perceive a "presentation" or "representation" of an object.
A common objection to these types of theories is that claiming that human beings can't know anything about the world in itself is a knowledge claim about the world in itself.