mcarl,
yes l of course agree with the fact that trout may take a fly or any other object with the belief it is a food source, and may be after rejecting what was not retain some sort of memory bank, in fact something l am convinced trout have the capacity to do, for if they did not they would be percentage easier to catch than they are, excluding recent stockers.
Same applies for most other fish species.
Which is no different to how we as humans make choices, you may put a stone in your mouth once assuming it to be a food source, or any other object or food source you subsequently dislike, if you reject it you are way less likely to do same.
Personally l do not relate my understanding of trout behaviour as science, what l have tried to do in some 55 years of trout fishing is to relate my understanding to ways and means to catch those fish and that brings into being many issues.
Saying that there are many mysteries that l doubt we will ever know the answers too. One of which my last post reflected so far as why one very small addition of color made a great deal of difference, not to the odd few fish but a great number.
Davy.