general categorization. I takesuchpotentialunificationtobea reason foroptimism, as itdraws a principled connection
between two pre-existing robust lines of research.
6.9 Issues of acquisition
Finally we can come back to an important issue raised toward the end of section 6.3:
How do language learners tell the difference between productive and semi-productive processes?
To review the position so far: the difference between semi-regular and regular patterns of morphology is that items in
a semi-regular pattern are simplystored, and alltherelations amongthem areimplicit. Bycontrast,regular patterns are
distinguished by having an extra ite min the lexicon, an 1-rule such as the suffix-d, with a variable in it. The variable
enables the affix to unify with other pieces of structure. The previous section has added a new piece to this story:
stored regulars inherit structure fro msuch ite ms.
How does this bear on acquisition? In order to make the question a bit more vivid, let me offer yet another case of
contrast between productive and semi-productive morphology, this time in the system of English verb-particle
combinations. A curious subclass of idiomatic verb-particlecombinations appears to have become semi-productivein
the past thirty years. They all mean roughly‘go into an unusual mental state’; the particle is alwaysout. Curiously, the
“verb”need notbe a verb or evenan independently attested word. The class is semi-productivebecause each example
(and its meaning) must be learned individually, hence lexically listed. (The judgments of relative recency are only my
best guesses; and speakers may differ on their judgments of transitivity.)
(39) a.Intransitives
[older examples] pass out, black out, conk out,fink out, crap out, chicken out; [more recent]flake out, zonk
out, zone out, bliss out,flip out, space out, phase out, crump out, veg out, chill out
b. Transitives
[older] knock NP out, bu mNP out, fake NP out; [ more recent] gross NP out, weird NP out, creep NP out
c. Intransitive or transitive
[older] burn (NP) out, poop (NP) out, tucker (NP) out; [more recent] freak (NP) out, wig (NP) out, stress
(NP) out, mellow (NP) out