Full Idea
The weakest version of representationalism, found in Russell, asserts that there is no resemblance to reality on the level of secondary qualities, and also that primary qualities exhibit only a structural isomorphism.
Clarification
'Isomorphism' means have an identical organisation
Gist of Idea
Russell's representationalism says primary qualities only show the structure of reality
Source
report of Bertrand Russell (Problems of Philosophy [1912]) by Howard Robinson - Perception IX.2
Book Reference
Robinson,Howard: 'Perception' [Routledge 2001], p.213
A Reaction
This seems a plausible thing to say about, say, shape, but it is not clear how the idea works for hardness or mass. The sense of touch seems to be much more directly in contact with actual primary qualities than visions does (let alone smell or hearing).