FINST

Pylyshyn (1989, 1994, 2001, 2003, 2007) argues that an individuated entity – a visual object – is preattentively tagged by an index, called a FINST (for ‘fingers of instantiation’).  Only a limited number (four) of FINSTs are available; once assigned to an object, a FINST remains attached to it even as the object changes its location or other properties.  The revolutionary aspect of FINSTs is that they are presumed to individuate and track visual objects without delivering a description of them, and without explicitly representing their location.  Pylyshyn (2007) argues that this is the visual equivalent of the use of indexicals or demonstratives in language.  “Think of demonstratives in natural language -- typically words like this or that.  Such words allow us to refer to things without specifying what they are or what properties they have” (Pylyshyn, 2007, p. 18).  FINSTs are visual indices that operate in exactly this way.  They are analogous to placing a finger on an object in the world, and (while not looking) keeping the finger in contact with it as the object moved or changed (thus the term ‘fingers of instantiation’).  As long as the finger is in place, the object can be referenced (‘this thing that I am pointing to now’), even though the finger does not deliver any visual properties.

References:

1. Pylyshyn, Z. W. (1989). The role of location indexes in spatial perception: A sketch of the FINST spatial-index model. Cognition, 32, 65-97.
2. Pylyshyn, Z. W. (1994). Some primitive mechanisms of spatial attention. Cognition, 50(1-3), 363-384.
3. Pylyshyn, Z. W. (2001). Visual indexes, preconceptual objects, and situated vision. Cognition, 80(1-2), 127-158.
4. Pylyshyn, Z. W. (2003). Seeing and Visualizing: It's Not What You Think. Cambridge, Mass.: MIT Press.
5. Pylyshyn, Z. W. (2007). Things and Places: How The Mind Connects With The World. Cambridge, Mass.: MIT Press.

(Added March 2011)