We introduce a new lexical priming technique designed for use during uninterrupted spoken language comprehension. Subjects' eye movements were recorded as they heard a male voice giving instructions to move objects on a table. Target sentences contained a prepositional phrase attachment ambiguity (e.g., "Now, I'd like you to feel the frog with the feather"), where "with the feather" could indicate an instrument or a noun phrase modifier. At the onset of the target verb, a prime verb of matched duration was uttered by a female and mixed into the digitized audio-track. Two types of prime verbs were compared: Instrument-biased primes (e.g., "hit") which strongly prefer to take an Instrument role; and Modifier-biased primes (e.g., "move") which rarely take an Instrument role.
Referential scenes were designed to support an instrument interpretation, i.e., One-Referent scenes, containing, e.g.: a single frog holding a small feather; a horse wearing a bow; a large feather; and an unrelated object. In this case, looks to the potential instrument (the large feather) and hand-actions involving this object (i.e., picking up the feather and using it to feel the frog) can be taken as on-line and off-line measures respectively of listeners' commitment to an instrument interpretation.
Although subjects reported at the end of the experiment that they rarely identified prime words, the structural preferences of these primes influenced parsing processes. In particular, Modifier-biased primes, as compared to Instrument-biased primes, reliably reduced the proportion of time listeners spent looking at the potential instrument upon hearing "with the feather" (both p<.05). In addition, hand-actions involving the potential instrument were less for Modifier-biased primes (34%) than Instrument-biased primes (44%), although this effect was only marginally significant by subjects (p=.06). A second experiment was also conducted with scenes that supported a modifier analysis, i.e., Two-Referent scenes, replacing the horse with another frog. As expected, these scenes eliminated almost all instrument actions, but still showed a small influence of prime-type on the amount of time listeners spent inspecting the potential instrument, with this effect being reliable only in the subject analysis.
The findings indicate that the auditory recognition of a verb can
activate argument roles that are tied to specific syntactic forms. The
results were obtained even though the instrument objects used in the
experiments were almost all poor instruments for the prime verbs,
suggesting that the overlap in verb argument structure between the target
and the prime was the source of these effects. Finally, we will discuss
the implications of these results for exposure-based models of
comprehension, which support an important role for lexical-distribution
cues in on-line parsing decisions.