To understand metarepresentation it is necessary to understand the concepts of REPRESENTATION and MENTAL REPRESENTATION. The term representation is used when one thing stands for another. For example, a map may stand for the layout of a place. Mental representation is used to describe the representation in the mind of external events, past events or imaginary events. Perceptions are representations of external events. For example, ‘greenness’ is a mental representation of light of a certain wavelength viewed under normal conditions. Recollections are mental representations of past events. Ideas and mental images are representations of how things might be, could be (or could not be), or will be. Mental representations are conscious and occur in the explicit domain; that is, they are experienced by the person and can be described or talked about. Information in the implicit domain includes skills which are acquired but which cannot be fully described. For example, musical expertise can be demonstrated but not adequately described.
Three levels of mental representation can usefully be distinguished (Leslie, 1987). Primary representations are about how the world is now, including perceptions and knowledge of constant relationships in the world. Secondary representations are decoupled from the world as it is now, in that they represent things as they could be, as they once were, or as they will be. Secondary representations are required to recollect the past as an event different from the present, to make propositions or generate ideas and to engage in pretend play. According to Perner (1993), children less than about 18 months old cannot form secondary representations and therefore live entirely in the present. For example, a very young child may play with a toy car only as an object. Older children can form secondary representations which allow them to consider multiple alternatives: for example, they could regard a toy car as simultaneously ‘being a car’ and ‘being a piece of plastic’. The ability to form multiple representations is a prerequisite to forming metarepresentations.
A metarepresentations depicts something as being a representation of a subject and defines the relation between the subject and its representation (Pylyshyn, 1978). This can be illustrated by considering misrepresentations. Perception requires mental representation but understanding that perceptions are mental representations, and that your perception may differ from reality, requires metarepresentation. For example, to know that you are experiencing a visual illusion requires the ability to form a metarepresentation of the relationship (and potential difference) between perception and reality. It is the understanding of the relationships between representations which constitutes the metarepresentation. Metarepresentation is necessary during cognitive processing in order to ‘label’ mental representations with the type of cognitive process of which they are a product. It is necessary to know, for example, which products of cognitive processing are percepts, known facts, memories, ideas, or expectations. Memories are distinguished from knowledge because the former has a ‘label’ or ‘episodic trace information’ which imbues it with the mental quality of a recollection (Tulving, 1985). Failure to attach cognitive labels may result in imagery being misinterpreted as perceptions and ideas being misinterpreted as known facts. These sorts of errors may contribute to the HALLUCINATION and DELUSION of PSYCHOSIS (Frith, 1992). For example, one form of auditory hallucination associated with SCHIZOPHRENIA is ‘thought broadcast’: ‘It was like my ears being blocked up and my thoughts shouted out’. In this case the patient recognizes his own thoughts but experiences them as if they were perceptions of the outside world. With more extreme examples, such as ‘delusions of control’ and ‘thought insertion’, the mislabelling is complete and the patient is convinced that the products of internal cognitive processes (thoughts and intentions) are emanating from the outside world.
Metarepresentation is particularly important for understanding that another person may hold beliefs (mental representations) that are different from your own mental representations and that neither necessarily accords with the real world. Metarepresentation is therefore necessary for the development of complex social interactions in which it is necessary to know who knows what, and, on occasions, to practice deceit. The mental ability to form metarepresentations is a prerequisite for the ability to develop a THEORY OF MIND, which includes the ability to understand that beliefs are constrained by access to information. Patients with AUTISM have a specific difficulty with theory-of-mind tasks concerning the beliefs of other people which depend upon metarepresentation. It is not yet resolved, however, whether autism is associated with a general problem of metarepresentation or whether this problem is restricted to the domain of social interactions.
