Alzheimer’s Disease and Herpes Simplex Encephalitis



was estimated to occur in less than 1% of the healthy
control population (two-tailed).

Patients were classified as displaying strong dissocia-
tions if they were (a) impaired at both tasks and (b)
showed a significant discrepancy across category; and
classified as displaying a
classical dissociation if they
were (a) impaired in one category, but performed
normally on the other and (b) showed a significant
discrepancy between the two categories (see Crawford
& Garthwaite, 2005; Crawford, Garthwaite, & Gray, 2003).

These methods of testing for deficits and for differ-
ences (i.e., dissociations) are to be preferred over the
use of
z and zD as they treat the statistics of the control
sample as statistics rather than as population parame-
ters. Moreover, Monte Carlo simulations show that the
RSDT (Crawford & Garthwaite, 2005) provides excellent
control over Type 1 error rate (regardless of whether the
data are heavily skewed, the control sample is small in
size, or the correlation between tasks). We contrasted
results from application of this method with those
derived from applying, on the same data, those derived
from using
x2—the method most frequently used to
evaluate discrepancies in living/nonliving accuracy in
single cases (Laws, in press). Programs to run the RSDT
analyses can be downloaded from
www.abdn.ac.uk/
%7Epsy086∕dept∕psychom.htm.

Acknowledgments

We thank Dr. Ivry and the reviewers for insights and helpful
comments on an earlier version of this article.

Reprint requests should be sent to Dr. Keith R. Laws, School of
Psychology, University of Hertfordshire, College Lane, Hat-
field, Hertfordshire AL10 9AB, UK, or via e-mail: keith.laws@
ntu.ac.uk.

Note

1. Four dementia of Alzheimer’s type patients were not test-
ed on this task.

REFERENCES

Capitani, E., Laiacona, M., Mahon, B., & Caramazza, A. (2003).
What are the facts of semantic category-specific deficits? A
critical review of the clinical evidence.
Cognitive
Neuropsychology, 20, 213-261.

Crawford, J. R., & Garthwaite, P. H. (2005). Testing for
suspected impairments and dissociations in single-case
studies in neuropsychology: Evaluation of alternatives using
Monte Carlo simulations and revised tests for dissociations.
Neuropsychology, 19, 318-331.

Crawford, J. R., Garthwaite, P. H., & Gray, C. D. (2003).
Wanted: Fully operational definitions of dissociations in
single-case studies.
Cortex, 39, 357-370.

Folstein, M. F., Folstein, S. E., & McHugh, P. R. (1975).
‘‘Mini-mental state’’: A practical method for grading the
cognitive state of patients for the clinician.
Journal of
Psychiatric Research, 12, 189-198.

Gainotti, G. (2000). What the locus of brain lesion tells
us about the nature of the cognitive defect underlying
category-specific disorders: A review.
Cortex, 36,
539-559.

Garrard, P., Patterson, K., Watson, P. C., & Hodges, J. R.
(1998). Category specific semantic loss in dementia of
Alzheimer’s type. Functional-anatomical correlations from
cross-sectional analyses.
Brain, 121, 633-646.

Gonnerman, L. M., Anderson, E. S., Devlin, J. T., Kempler, D.,
& Seidenberg, M. S. (1997). Double dissociation of
semantic categories in Alzheimer’s disease.
Brain and
Language, 57, 254-279.

Hachinski, V. C., Iliff, L. D., Zihka, E., Duboulay, G. H.,
McAllister, V. L., Marshall, J., Russell, R. W. R., & Symon, L.
(1975). Cerebral blood flow in dementia.
Archives of
Neurology, 32, 632-637.

Lambon Ralph, M. A., Howard, D., Nightingale, G., &
Ellis, A. W. (1998). Are living and non-living
category-specific deficits causally linked to impaired
perceptual or associative knowledge? Evidence from a
category-specific double dissociation.
Neurocase, 4,
311-338.

Laws, K. R. (in press). ‘‘Illusions of Normality’’: A
methodological review of category-specific naming.
Cortex.

Laws, K. R. (1998). A leopard never changes its spots.
Cognitive Neuropsychology, 15, 467-479.

Laws, K. R. (2004). Strange and neglected domains in
category specificity: The ‘‘normal’’ and the
‘‘nonliving’’.
History and Philosophy of Psychology, 6,
19-39.

Laws, K. R., Evans, J. J., Hodges, J. R., & McCarthy, R. A. (1995).
Naming without knowing and appearance without
associations—Evidence for constructive processes in
semantic memory.
Memory, 3, 409-433.

Laws, K. R., Gale, T. M., Leeson, V. C., & Crawford, J. R.
(2005). When is category specific in dementia of Alzheimer’s
type?
Cortex, 41, 452-463.

Laws, K. R, Leeson, V. C., & Gale, T. M. (2003). Inflated and
contradictory category naming deficits in Alzheimer’s
disease?
Brain and Cognition, 53, 232-234.

McKhann, G., Drachman, D., Folstein, M., Katzman, R.,
Price, D., & Stadlan, E. M. (1984). Clinical diagnosis of
Alzheimer disease: Report of the NINCDS-ADRDA work
group.
Neurology, 34, 939-944.

Mauri, A., Daum, I., Sartori, G., Riesch, G., & Birbaumer, N.
(1994). Category-specific semantic impairment in
Alzheimer’s disease and temporal lobe dysfunction: A
comparative study.
Journal of Clinical and Experimental
Neuropsychology, 16,
689-701.

Sartori, G., Job, R., & Zago, S. (2002). A case of domain-specific
semantic deficits. In E. M. E. Forde & G. W. Humphreys
(Eds.),
Category specificity in brain and mind (pp. 25-49).
Hove, Sussex: Psychology Press.

Silveri, M. C., Daniele, A., Giustolisi, L., & Gainotti, G. (1991).
Dissociation between knowledge of living and non-living
things in dementia of the Alzheimer’s type.
Neurology, 41,
545-546.

Tippett, L. J., Grossman, M., & Farah, M. J. (1996). The
semantic memory impairment of Alzheimer’s disease:
Category specific?
Cortex, 32, 143-153.

Warrington, E. K., & Shallice, T. (1984). Category specific
semantic impairments.
Brain, 107, 829-854.

Laws and Sartori 1459



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