Gs. Waters et al., PROCESSING CAPACITY AND SENTENCE COMPREHENSION IN PATIENTS WITH ALZHEIMERS-DISEASE, Cognitive neuropsychology, 12(1), 1995, pp. 1-30
A sentence-picture matching task was used to test the ability of patie
nts with dementia of the Alzheimer's type (DAT) and age- and education
-matched control subjects to interpret nine different sentences. These
sentences differed on two dimensions-syntactic complexity and number
of propositions. Subjects were tested on this task with no concurrent
task (alone) and while concurrently remembering a digit load that was
on less than their span or equivalent to their span. Neither group of
subjects showed an effect of syntactic complexity, but DAT patients di
d show an effect of the number of propositions in a sentence. For all
subjects, comprehension of sentences with more propositions was more g
reatly affected by larger digit loads, but comprehension of more compl
ex syntactic structures was not. The performance of DAT patients was m
ore affected than that of the control subjects on the digit task, but
they were not disproportionately impaired on the sentence types which
were more complex or had more propositions compared to normals. The re
sults are discussed in relationship to the hypothesis that there is a
sentence comprehension impairment in DAT that is related, to the proce
ssing resource requirements of different aspects of the sentence compr
ehension process.