Full Idea
We may say that a perceptual concept refers to that entity which normally causes classificatory uses of that concept...but this won't work because such deployments are often caused by things which the concept doesn't refer to. A model might cause 'bird'.
Gist of Idea
Perceptual concepts can't just refer to what causes classification
Source
David Papineau (Thinking about Consciousness [2002], 4.6)
Book Reference
Papineau,David: 'Thinking about Consciousness' [OUP 2004], p.113
A Reaction
This rejects the causal theory of perceptual concepts. I like the approach, because classifying things strikes me as absolutely basic to what brains do. To see that x is a bird is to place x in the class of birds.