K. Oberauer et R. Kliegl, Beyond resources: Formal models of complexity effects and age differences in working memory, EUR J COG P, 13(1-2), 2001, pp. 187-215
We explore several alternative formal models of working memory capacity lim
its and of the effect of ageing on these capacity limits. Three models test
variations of resource accounts, one assumes a fixed number of free slots
in working memory, one is based on decay and processing speed, one attribut
es capacity limits to interference, and one to crosstalk between associatio
ns of content and context representations. The models are evaluated by fitt
ing them to time-accuracy functions of 16 young and 17 old adults working o
n a numerical memory-updating task under varied memory-load conditions. Wit
h increasing complexity (i.e., memory load), both asymptotic accuracy and t
he rate of approach to the asymptote decreased. Old adults reached lower as
ymptotes with the more complex tasks, and had generally slower rates. The i
nterference model and the decay model fit the individual time-accuracy func
tions reasonably well, whereas the other models failed to account for the d
ata. Within the interference model, age effects could be attributed to the
older adults' higher susceptibility to interference. Within the decay model
, old adults differed from young adults by a higher degree of variability i
n the activation of working memory contents.