tions show that the RSDT (Crawford & Garthwaite,
2005) used in the current study provides excellent
control over Type 1 error rate (even when patient data
are heavily skewed through poor performance).
The dissociations reported here within one patient
are indistinguishable from those typically reported be-
tween patients in the category-specific literature. De-
spite the equivalence of paradoxical and ‘‘regular’’
dissociations (and double dissociations) in terms of their
acceptability as empirical evidence, it may be that both
are unreliable. Hence, we should not take any one (or
even some combinations) test as prima facie evidence of
a category effect in one direction. As noted above,
reliability, both across task and across time, are critical
issues for future studies to consider in the case study
approach.
METHODS
Experiment 1
Participants
The study included 19 (15 women and 4 men) patients
with probable Alzheimer’s dementia and 15 healthy
elderly control subjects (9 women and 6 men). The 19
Alzheimer’s patients met the National Institute of Neu-
rological and Communicative Disorders and Stroke/Alz-
heimer’s Disease and Related Disorders Association
(NINCDS/ADRDA) criteria for probable Alzheimer’s dis-
ease (McKhann et al., 1984). All 19 patients had
Hachinski scores of less than 4 (Hachinski et al.,
1975) and a Mini-Mental State Examination (MMSE)
score below 24/30 (Folstein, Folstein, & McHugh,
1975). All underwent CT or MRI scanning, together
with a screening battery, to exclude treatable causes of
dementia. Patients with major depression, a history of
stroke or TIA, alcoholism, head injury, or major med-
ical illnesses were excluded. Patients were recruited in
three hospitals and in four nursing homes located in
Veneto (Italy) and were an unselected series.
The Alzheimer’s patients and controls were matched
for age [mean (SD): 77.9 (8.7) vs. 75.33 (4.2): F(1,33) =
1.02, p > .05] and years of education [4.73 (0.80) vs. 6.28
(4.76): F(1, 33) = 1.5, p > .05]. They did, of course,
differ significantly in their MMSE [19.31 (2.45) vs. 27.4
(1.11): F(1,33) = 126, p < .001].
Tasks
1. Picture naming: 32 living (20 animals and 12 fruits
and vegetables) and 32 nonliving items matched for
frequency, familiarity, and visual complexity (Sartori,
Job, & Zago, 2002).
2. Feature verification: 80 living and 64 nonliving
items (e.g., ‘‘a tiger has stripes’’). All features were
perceptual. The examinee is required to respond if the
feature belongs to the concept or not (Sartori et al.,
2002). Half of the stimuli required a ‘‘yes’’ response and
half required a ‘‘no’’ response.
3. Naming-to-description: Originally published by
Lambon-Ralph, Howard, Nightingale, and Ellis (1998)
as a feature verification task, it was adapted to Italian as a
naming-to-description task. Sixteen animals and 12 ob-
jects were used. Each concept was described by a per-
ceptual and a functional/associative description, thus
yielding a total of 32 descriptions for living and 24
descriptions of nonliving.
Experiment 2
Participants
This experiment included 15 (7 women and 8 men)
patients with HSE and 12 healthy control subjects (6
women and 6 men). Herpes Simplex patients were all
recruited in three hospitals located in Veneto (Italy),
were native speakers of Italian, and all satisfied the
following criteria: all had polymerase-chain-reaction-
proven HSE; all showed pathologic changes at CT scan
or MRI which were usually bilateral, in the medial-
temporal and inferior frontal areas; all underwent treat-
ment with Acyclovir; and all were examined between 13
and 46 months postonset.
The HSE patients and controls were matched for
mean (SD) age [53.66 (14.77) vs. 54.47 (12.63): F(1,25) =
0.22, p = .88] and mean (SD) years of education [7.73
(3.17) vs. 10.41 (4.31): F(1,25) = 3.47, p > .05]. They did
differ significantly in their mean [SD] MMSE scores
[24.66 (3.26) vs. 28.68 (0.72): F(1,25) = 17.31, p < .001].
Tasks
The same three tasks used for the Alzheimer’s patient
were administered to the HSE patients.
Methods of Analysis Used to Establish
Category Specificity
The data for each individual participant were examined
by comparing performance with their respective control
group using the RSDT (Crawford & Garthwaite, 2005)
for testing for deficits and dissociations in single-case
studies. Of course, it is possible for patients to be im-
paired at naming living or nonliving things, but that the
difference between their scores does not reach signifi-
cance; equally, a patient may be severely impaired on
both tasks, but still show differential impairment. This
method examines whether the discrepancy observed for
the patient is significantly different from the discrepan-
cies observed for controls and provides a point estimate
of the abnormality of the individual’s discrepancy (i.e., it
estimates the percentage of the population that would
obtain a more extreme discrepancy). Patient perform-
ance was classified as impaired if the discrepancy score
1458 Journal of Cognitive Neuroscience
Volume 17, Number 9