Full Idea
According to the 'respects' view, our learning of yellow by ostension would have depended on our first having been told or somehow apprised that it was going to be a question of color.
Clarification
'ostension' is pointing out
Gist of Idea
To learn yellow by observation, must we be told to look at the colour?
Source
Willard Quine (Natural Kinds [1969], p.122)
Book Reference
Quine,Willard: 'Ontological Relativity and Other Essays' [Columbia 1969], p.122
A Reaction
Quine suggests there is just one notion of similarity, and respects can be 'abstracted' afterwards. Even the ontologically ruthless Quine admits psychological abstraction!