The clearest piece of evidence to date for purely syntactic priming comes
from Bock and Loebell’s (1990) seminal finding that intransitive locatives
with prepositional phrases primed passives as much as passive primes did.
However, their intransitive and passive sentences all included the
preposition *by*, raising the possibility that *by* was responsible for, or
at least essential to, priming across the different constructions.
Here we demonstrate
that abstract syntactic phrase structure is neither sufficient for passives
to be primed nor is it necessary. We conclude that passive priming is
largely or completely attributable to the *by*-phrase adjunct.