Hi Frank,

FK> (having no psychology background) I find the
FK> distinction between perception and aperception
FK> confusing. Both seem to involve discriminating using
FK> memory.

In my opinion perception is more primary, in Buddhist terms it refers
to the arising of impression (phassa - contact) on the basis of sense
object, sense organ and consciousness, and consequent categorization,
emotional reaction and decision. It's a rather general term which in
some usages includes apperception.

Apperception (ad + perceptio, to perception), refers to the process
when impression is integrated in life experience, associated with other
impressions, categorized, classified, given a significance and labeled.

Though these terms are somewhat fuzzy and similar, there's an evident
difference.

FK> I've also never been clear on what the aggregate of
FK> consciousness is, and how it differs from the
FK> aggregate of perception (sanna).

There's a good article on vi~n~naa.na:
http://sino-sv3.sino.uni-heidelberg.de/FULLTEXT/JR-PHIL/donald.htm

In most cases it means 'cognitive or perceptive consciousness'.
That's the third component needed for impression to arise. When
particular sense consciousness is absent, as in case of sleep,
unconsciousness, deep jhana or concentration on another sense, the
impression doesn't come to be.

FK> The examples from the sutta really don't shed any
FK> light on how perception and consciousness differ.

Well, there's another sutta with clearer difference:
http://www.accesstoinsight.org/canon/samyutta/sn22-057.html

Dimitry