(Metzinger, 2003) distinguishes four different types of introspection.
Type 1 - "External attention"
- Introspection1 is sub-symbolic metarepresentation operating on a pre-existing, coherent world-model. This type of introspection is a phenomenal process of attentionally representing certain aspects of an internal system state (this is why it can be conceptually described as a form of introspection), the intentional content of which is constituted by a part of the world depicted as external.
The accompanying phenomenology is what we ordinarily describe as atten- tion or the subjective experience of attending to some object in our environ- ment. Introspection corresponds to the folk-psychological notion of attention.
Type 2 - "Consciously experienced cognitive reference"
- Introspection2 refers to a conceptual (or quasi-conceptual) form of metarepresentation, operating on a pre-existing, coherent model of the world. This kind of introspection is brought about by a process of phenomenally representing a cognitive reference to certain aspects of an internal system state, the intentional content of which is constituted by a part of the world depicted as external.
Phenomenologically, this kind of introspection is constituted by all experi- ences of attending to an object in our environment, while simultaneously recognizing it or forming a new mental concept of it: it is the conscious expe- rience of ongoing cognitive reference.
Type 3 - "Inward attention" and "inner perception"
- Introspection3 is a subsymbolic metarepresentation operating on a pre-existing, coherent self-model, i.e., a dynamic, multimodal representation of the system as a whole. This type of introspective experience is generated by processes of phenomenal representation, which direct attention towards certain aspects of an internal system state, the intentional content of which is being constituted by a part of the world depicted as internal.
The phenomenology of this class of states is what in everyday life we call "inward-directed attention." On the level of philosophical theory it is this kind of phenomenally experienced introspection that underlies classical theories of inner perception, e.g., in John Locke or Franz Brentano
Type 4 - "Consciously experienced cognitive self-reference”
- Introspection4 is a conceptual (or quasi-conceptual) kind of metarepresentation, again operating on a pre-existing, coherent self-model. Phenomenal representational processes of this type generate conceptual forms of self-knowledge, by directing cognitive processes towards certain aspects of internal system states, the intentional content of which is being constituted by a part of the world depicted as internal.
The general phenomenology associated with this type of representational activity includes all situations in which we consciously think about ourselves as ourselves. On a theoretical level, this last type of introspective experience clearly constitutes the case in which philosophers of mind have traditionally been most interested: the phenomenon of cognitive self-reference as exhibited in reflexive self-consciousness.
- For the notion of a “self-model” see Metzinger 1999, 2000, 2003.