It has recently been suggested that working memory
could be conceived as two symmetrical subsystems with
analogous structure and processing principles: a declarative
working memory storing objects of thought available for
cognitive operations, and a procedural working memory holding
representations of what to do with these objects (Oberauer,
Psychology of learning and motivation 51: 45-100, 2009).
Within this theoretical framework, the two subsystems are
thought to be independent and fueled by their own capacity.
The present study tested this hypothesis through two experiments
using a complex span task in which participants were
asked to maintain consonants for further recall while
performing response selection tasks. In line with Oberauer’s
conception, the load of the procedural working memory was
varied by manipulating the number of stimulus-response mappings
of the response selection task. Increasing the number of
these mappings had a strong detrimental effect on recall
performance. Besides contradicting Oberauer’s proposal, this
finding supports models that assume a resource-sharing between
processing and storage in working memory.