Conclusion
Overall, we find clear evidence of common processing of auditory and
visual motion in a speed discrimination task. Our findings fit well with
an emerging picture from neuroimaging studies showing that auditory and
visual motion are both represented in hMT+25. While
visual motion is encoded earlier in the visual pathway in V1 neurons, it
is activity in hMT+ that correlates with the perception of motion, as
discussed above. If motion from both modalities were processed in hMT+,
it would parsimoniously explain the unimodal observations of
near-identical psychometric slopes and very similar priming functions,
as well as the crossmodal data showing priming between vision and
audition in both directions. Because hMT+ responds very effectively
long-range apparent motion (a series of position
‘snapshots’71), proposing hMT+ as the region of common
audiovisual motion processing is agnostic about the ultimate nature of
auditory motion as it can be driven by smooth continuous motion or by
snapshots of discrete positions over time.