| |
Abstract:
Abstract: Previous research has shown that relatively
distinct cortical regions mediate spatial, verbal and object
working memory. Furthermore, behavioral evidence has shown that
these types of information can be stored simultaneously without
interference (e.g. Sanders and Schroots, 1969), even when each
buffer is loaded to capacity. Together these data suggest
functional independence of these working memory systems. However,
while there is general consensus on the independence of storage in
spatial, verbal and object working memory, the architecture of
executive control in working memory is less clear. An influential
model of working memory proposed by Baddeley and colleagues asserts
a unitary executive. In order to explore this issue, we used a
working memory paradigm (the 2-back task) that required maintenance
of temporal order and constant updating of the contents of
memory--operations that have been characterized as examples of
executive processing. Subjects performed the 2-back task while
remembering either spatial location, letter identity or object
shape. In a dual-load condition, subjects were instructed to
remember more than one kind of information at the same time. We
reasoned that if a unitary executive process coordinates multiple
modalities of working memory, then performance should be worse in
the dual-load than in the single-load conditions. However, neither
reaction time nor accuracy revealed a dual-load cost in these
experiments. Implications for executive architectures will be
discussed.
|
