Chung (2006) argues that preposition omission under sprouting (John
danced, but I don’t know *(with) who(m)) is degraded as compared to
sluicing due to an identity condition requiring all words that are
omitted in the sluice to be given in the antecedent. We present a rating
and a self-paced reading experiment investigating whether this pattern
can be explained by processing mechanisms: The wh phrase is more likely
and therefore processed faster (Hale 2001) under sluicing. Our data show
that not only mismatches violating Chung’s condition are degraded and
read more slowly.