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Abstract:
When two pictures of an object implying motion are presented
one after the other, observers take longer to decide if the second
picture is different to the first when that object is further along
the implied plane of motion. The time taken to decide that the
second picture is different when the motion implied is forward,
versus backwards, is called 'representational momentum' (RM). As
semantic factors can modulate RM it is considered to be an example
of the cognitive representation of motion. However previous
neuroimaging research has shown that area V5/MT, an area
traditionally associated with perceptual processing of motion, is
implicated in this phenomenon. Transcranial magnetic stimulation
(TMS) can be used to explore cognition through disruption of neural
processing within selective areas of cortex. The hypothesis that an
absence in RM would be revealed when TMS was applied to areas of
cortex responsible for perception of motion (V5/MT) compared to a
control area (vertex) was tested. ANOVA suggested disruption of
cortical functioning in V5/MT resulted in the absence of RM (i.e.
magnetic stimulation improved ability to categorise motion-implying
photographs as different). This suggests that this area of the
brain may play a necessary role for representational momentum.
These data, combined with recent functional neuroimaging studies,
suggest that V5/MT is involved in the conceptual as well as
perceptual processing of motion (since motion is implied but not
perceived in 'RM')
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