Neurocase (2001) Vol. 7, pp. 303–317

© Oxford University Press 2001

The Right Hemisphere’s Role in Action Word Processing:
a Double Case Study
Bettina Neininger1,2 and Friedemann Pulvermüller1,2,3
1Department of Psychology, University of Konstanz, PO Box D25, 78457 Konstanz, 2Lurija Institut, Kliniken Schmieder
Allensbach, Postfach 240, 78473 Allensbach, Germany and 3Cognition and Brain Sciences Unit, Medical Research Council,
15 Chaucer Road, Cambridge CB2 2EF, UK

Abstract
Word category-specific deficits were investigated in two patients with right hemispheric lesions and hemiparesis
affecting the left extremities. Words from three categories, action verbs, nouns with strong visual associations and
nouns with both strong action and visual associations, were presented in a lexical decision task. The stimulus
categories were matched for word length and frequency. In both patients, responses to action verbs were slowed
and/or less accurate compared with the other word categories. This was so even in the patient with a minor lesion in
the motor, pre-motor and somatosensory areas of the hand representation. Control subjects did not show category
differences when tested with the same stimulus materials. These results are consistent with the view that the cortical
areas involved in the programming of body movements, even those in the hemisphere not dominant for language,
specifically contribute to and are necessary for the processing of words referring to such movements. As an
alternative, the affected brain areas may be of particular relevance for the processing of words from the lexical
category of verbs. The results are consistent with a brain model of language based on Hebb’s cell assembly concept.

Introduction
The issue of word category-specific cortical processes has
gained some attention in recent neurophysiological and neuropsychological research. While early models of brain mechanisms of language postulated that two small centres in the
dominant hemisphere are the only ones relevant for language
(Wernicke, 1847; Lichtheim, 1885), it is, by now, well
established that regions outside these traditional core language
areas of Broca and Wernicke make additional contributions
to the processing of words. Many of these additional areas
are not equally relevant for all word types, but rather
for linguistic material with special properties. Thus, the
‘additional areas’ or supplementary language areas are of
particular interest if category-specific processes are under
investigation. Supplementary language areas have been proposed to be housed in the language-dominant hemisphere,
but there is increasing evidence that the non-dominant hemisphere, usually the right, is also relevant for processing
particular word types (Pulvermüller, 1999).
Within the dominant left hemisphere, various areas have
an established role in word processing. Damasio and Tranel’s
(1993; Damasio et al., 1996) neuropsychological and neuroimaging studies indicate that access to tool and animal names
is mediated by specific sites in the left inferior temporal lobe,

while verbs are accessed in the left inferior frontal lobe.
Daniele et al.’s (1994) analysis of neuropsychological data
suggests that left frontal and temporal areas differentially
contribute to the processing of verbs and nouns, respectively,
although there are exceptional cases that do not neatly fit in
this rough scheme. Neuroimaging studies by Martin et al.
(1996; Chao et al., 1999) indicate that the naming of animals
and tools activates distinct areas in the left frontal, temporal
and occipital lobes, and functional brain mapping further
supports a differential involvement of frontal and occipital
lobes of both hemispheres in the processing of words referring to actions and visually related words, respectively
(Pulvermüller et al., 1996, 1999a, b). These data are evidence
of differential contributions of supplementary language areas
in the dominant left hemisphere to the processing of specific
word categories (cf. Gainotti, 1998).
The fact that the dominant left hemisphere is not the only
one capable of word processing and lexical access has been
demonstrated by investigations in split brain and hemispherectomy patients. The non-dominant right hemisphere
alone is capable of processing stimulus words, at least if they
are common and concrete in meaning (Zaidel, 1976, 1983,
1998). A right hemispheric contribution to the processing of

Correspondence to: Bettina Neininger, Department of Psychology, University of Konstanz, PO Box D25, 78457 Konstanz, Germany. Tel: ⫹49 (0)7531 88
3086; Fax: ⫹49 (0)7531 88 2891; e-mail: bettina.neininger@uni-konstanz.de

304 B. Neininger and F. Pulvermüller

concrete words is further supported by physiological data
recorded from healthy individuals: whereas highly abstract
function words elicited strongly left lateralized brain
responses, content words (including nouns and verbs) elicited
more symmetrical evoked potentials over the hemispheres
(Neville et al., 1992; Pulvermüller et al., 1995). Finally, there
is also evidence suggesting that word processing is more
effective if both hemispheres have access to the stimulus
information compared with stimulation of the dominant left
hemisphere alone, implying a facilitatory effect of the right
hemisphere’s word processor on that of the left (Mohr et al.,
1994, 1996). These results further confirm the existence of
supplementary language areas outside the left hemispheric
language areas, and suggest category-specific processes even
on the non-dominant side.
The results obtained so far show:
(1) that the right hemispheric areas are activated when
certain words are being processed;
(2) that the right hemisphere can be sufficient for the processing of certain words;
(3) that the right hemisphere can facilitate the left hemisphere
in processing words.
What the studies available so far have not achieved is a
proof that the right hemisphere is necessary for the optimal
processing of specific word categories. Furthermore, one may
well argue that, while there is strong evidence for a differential
contribution of defined areas in the dominant left hemisphere
to word category-specific processes, such evidence is sparse
for the right. Here, we present two patients with right
hemispheric damage and ask whether word category-specific
deficits can be detected with fine-grained neuropsychological
experimental paradigms. If such deficits are present, it would
be possible to draw conclusions on the role of specific right
hemispheric areas to word category-specific processes and,
furthermore, they would support the idea that these right
hemispheric areas are necessary for the optimal processing
of certain types of words.
To generate hypotheses about the outcome of these experiments, we used a neurobiological model according to which
words are processed by cortical cell assemblies (Hebb,
1949) distributed over left perisylvian language regions
and supplementary language areas (Pulvermüller, 1999).
According to one view, the supplementary areas involved
depend on semantic word properties. Hebbian correlation
learning implies that a word frequently co-occurring with a
visual stimulus will be stored in the cortex by means of
strong connections between neurones in visual and language
areas. On the other hand, a word frequently used together
with an action performed by one’s own body will be laid
down by a strongly connected neurone ensemble including
neurones in action-related areas and the core language areas.
Action-related areas include the pre-motor and motor cortex,
the secondary and supplementary motor areas and additional
pre-frontal sites. Cell assemblies which underlie the cortical
processing of action and visually related words (Pulvermüller,

1999) are illustrated in Fig. 11. Importantly, neurones in both
hemispheres are related to the execution of body movements
and to the perception of objects, suggesting that action and
visually related areas in both hemispheres can contribute to
word processing.
The cell assembly model implies strong multiple reciprocal
connections of the neurones within one assembly. Activation
of an assembly is based on these multiple feedforward and
feedback connections. Therefore, a lesion anywhere in such
a widely distributed network should, in principle, reduce the
amount of activity flow when the assembly becomes active.
This may result in a degradation of word processing. If the
lesion is in a supplementary language area primarily housing
neurones of a particular word category, a category-specific
deficit may arise. It appears of theoretical interest whether
such deficits can result from right hemispheric lesions alone,
even if the left hemispheric core language areas are still intact.
We ask here whether the right frontal lobe is necessary
for processing action-related words. In an earlier study
(Pulvermüller et al., 1998), we investigated a group of
neurological patients with lesions in the right frontal lobe
and left-sided hemiparesis and compared their performance
with that of a group of matched healthy control persons
without brain injury. Although none of the patients exhibited
a clinically manifest aphasia, their lexical decisions were
substantially less accurate for action verbs compared with
visually related nouns matched for length and word frequency.
Comparison of the patients’ data with those of healthy
controls revealed a significant word category by group
interaction. We argued that it may be the involvement of
right hemispheric motor, pre-motor and adjacent pre-frontal
areas that underlies the word category-specific processing
deficit.
However, the shortcomings of group studies are very well
known (Caramazza, 1986), and with regard to our earlier
investigation, one may argue that the unavoidable variation
of lesion sites makes it impossible to attribute the word
category deficit to one particular lesion site. Therefore, we
reinvestigated the issue with selected single cases.
An additional possible shortcoming of our earlier study
was that the two word categories under investigation, action
verbs and visually related nouns, differed in more than one
respect. They were not only different with regard to their
semantics, that is, the visual stimuli versus actions they refer
to. They also belonged to different lexical categories, that is,
they were nouns and verbs, respectively. Based on the group
study, it is impossible to decide which of these variables,
their semantic or lexical features, was relevant for the specific
deficit obtained. In the present study, we used a third word
category. In addition to action verbs and visually related
nouns, we chose nouns exhibiting both associations of actions
and of visual stimuli. We expected that the ‘bimodal’ (or
‘multimodal’) nouns would group with one of the other two
categories therefore allowing inferences on word properties
determining category-specific deficits after defined right
hemispheric lesions. Before the experiment, we entertained

The right hemisphere’s role in action word processing 305

Fig. 1. Visually related nouns may be represented by cortical cell assemblies distributed over perisylvian and additional visual cortices, whereas action verbs
may be organized as assemblies distributed over perisylvian and additional motor cortices. Circles represent local neurone clusters and lines long-distance
connections. The left and right hemispheric parts of the networks are shown on the left and right, respectively.

three hypotheses about the relationship of right frontal lesions
and their effect on word processing, which we will sketch
briefly below.
(1) Lexical hypothesis. Lesions in the right frontal lobe cause
deficits along the lexical category boundary. Verbs should
suffer but not nouns, regardless of their semantic associations.
(2) Strong semantic hypothesis. All words that remind subjects of actions should suffer from lesions in the right
frontal lobe. This implies a processing impairment for
action verbs along with multimodal nouns. In contrast,
nouns with visual associations should do better.
(3) Weak semantic hypothesis. Only words primarily characterized by action associations should suffer from right
frontal lesions. Words primarily relying on visual associations and words with multimodal links should survive
a right frontal lesion relatively unimpaired. This last
hypothesis was guided by the idea that an extremely
widely distributed network including many neurones in
multiple supplementary language areas should be less
vulnerable to a focal lesion compared with a more focal
network.
Two patients with a lesion in their right hemisphere without
clinically apparent language disturbance were examined.
Again, the aims were: (i) to replicate the results of the earlier
group study (neither of the patients investigated here was a
member of the group examined earlier); (ii) to define more
precisely the range of lesions that can underlie the deficit;
and (iii) to draw inferences on which word properties
are relevant.

In addition, we chose to vary slightly our design to exclude
one possible caveat of the earlier study. Our stimuli were
then presented at fixation with one half of the word falling
in the left visual field (right hemisphere) and the other in the
right visual field (left hemisphere). Given that patients may
have had a deficit affecting visual processing, for example a
neglect or a spurious version thereof, it may be that our
patients (or a significant subgroup of them) had difficulty
perceiving the left side, that is, the beginning of the words.
Note that lesions in the right frontal lobe sometimes extend
into the right parietal lobe where a lesion may lead to neglect.
If the left half of the word is particularly difficult to process,
this may cause an artifactual word category effect if words
differ with regard to the information contained in their initial
and final letters. We used German words, and in this language,
verb endings are in most cases less informative than their
onsets, because letters such as ‘e’, ‘n’ or ‘t’ very frequently
occur in their final positions. Thus, verb onsets carry more
information than their ends, whereas in the case of nouns
there is either no or a less pronounced bias in this direction.
In conclusion, in the case of central presentation it is possible
that a hemineglect affecting the left hemifield or left-sided
visual extinction phenomena artificially cause a word category deficit.
To overcome this potential problem, we chose to present
all words bilaterally, such that two copies of each word were
simultaneously flashed to the left and right of fixation. In
this case, it is guaranteed that both hemifields, and thus both
hemispheres, receive the full information about the words
under investigation. A deficit affecting visual processing in

306 B. Neininger and F. Pulvermüller

Fig. 2. Reconstruction of GU’s cortical lesion. The lesion involved frontal areas as well as regions in the adjacent parietal and temporal cortices.
Table 1. Results of the neuropsychological assessments. Test results below
the normal performance range of the age group are indicated by asterisks
GU
Benton Test
8 (6)
d2 test
86.4
Corsi block tapping test
6
Token Test
0
Neglect screening
No neglect
Apraxia screening instrument 0
Oldfield laterality quotient
LQ ⫽ ⫹ 100
and decile values (handedness) R10
Left-handed family members 0
Rating of paresis
Paresis affecting
the left extremities
Language
Monolingual German

CE
6* (5)
96.4
4*
0
No neglect
0
LQ ⫽ – 45
L3
1
Minimal paresis
affecting the arm
Monolingual German

one hemifield may now still lead to a processing deficit but,
since the other hemisphere would nevertheless receive the
full information about each stimulus word, a category-specific
deficit could not be explained based on this abnormality.

Materials and methods
Subjects
At the time of the experiments, GU was 56 years old. He
was a German-speaking right hander without any left-handed
family members. According to the Oldfield inventory
(Oldfield, 1971), he was even a ‘pure’ right hander without
tendencies towards left handedness (see Table 1). He had
been formally educated for 9 years. In 1997 he suffered
from an ischaemic insult partially affecting the right middle
cerebral artery causing left hemiparesis. His ability to walk
was strongly affected and his left arm was almost without
function. Neither a computer tomogram (CT) nor a nuclear
magnetic resonance tomogram (NMR) was available at the

time of testing. Following the available radiologist’s reports,
we reconstructed the approximate cortical lesion as displayed
in Fig. 2. Note that the lesion primarily affected frontal areas,
but also involved adjacent parietal and temporal cortices.
There was no evidence of a left hemispheric lesion in
this patient.
CE was a 46-year-old male with 13 years of formal
education. Before his stroke, he worked in the medical area.
His native language was German. He reported to be a left
hander and he also reported that another member of his
family was left handed or ambidextrous. Closer examination
with the Oldfield inventory revealed a laterality quotient of
–0.45 resulting in a decile value of L3. Given his mild hand
preference, we prefer to speak about a tendency towards left
handedness. In 1998, he suffered from a watershed infarct at
the border of the supply areas of the middle and anterior
cerebral arteries in the right hemisphere causing discrete
paresis of the left arm. An NMR scan taken a few days after
this stroke revealed a white matter lesion also affecting a
small part of the pre-motor and primary motor cortex and an
even smaller part of adjacent somatosensory cortex. The
lesion extended into Brodmann areas 4, 6 and 8 of the frontal
lobe and into areas 1, 2, and 3 of the parietal lobe. Based on
Penfield and Rassmussen’s (1950) work, we estimated that
this lesion affected motor areas controlling the left arm,
although we note that, given the use-dependence change of
cortical representations as revealed, for example, in string
players (Elbert et al., 1994, 1995), such analogies between
anatomy and function must remain tentative. After his stroke,
CE returned to work. At the time of testing, he reported no
paresis, but only a residual deficit, a weakness of the left
arm. Figure 3a shows magnetic resonance imaging (MRI)
scans and Fig. 3b illustrates the lesion projected on to
Brodmann’s cortex map. There was no evidence of a left
hemispheric lesion.

The right hemisphere’s role in action word processing 307

Fig. 3. (a) Magnetic resonance imaging (MRI) scans obtained from patient CE. (b) Projection of CE’s lesion on to Brodmann’s cortex map. The lesion only
affects a small part of the pre-motor and primary motor cortex and an even smaller part of the somatosensory cortex.

Nine healthy subjects formed the control group. Their
mean age was 59 years (range 41–79 years) and their formal
education was 10.3 years (range 9–13 years). All controls
were monolingual native speakers of German, strongly right
handed, and without any cognitive or language impairments
as confirmed by each subject’s error-free performance on the
Token Test. Thus, the two patients focused on in this report
were within the ranges of age and years of education of the
control group.

Neuropsychological assessment
The Token Test (De Renzi and Vignolo, 1962), a test for
separating aphasics from other brain-damaged patients, was
used to assess the presence of an aphasia. The German
version of this test (Orgass, 1976) was administered. The
Token Test consists of a series of instructions of increasing
complexity. The patient has to follow them by pointing to or
manipulating coloured tokens of different size and form. The

308 B. Neininger and F. Pulvermüller

patients’ ability to read was screened by having them read
aloud a paragraph from the informed consent form, and
comprehension of written language was assessed using five
items from the sentence comprehension part of the Aachen
Aphasia Battery (Huber et al., 1983).
An apraxia questionnaire was used to screen actions
typically affected in apraxics. This screening instrument
contains 20 questions about facial apraxia, ideomotoric
apraxia with both symbolic and asymbolic tasks and ideatoric apraxia.
A paresis screening instrument was constructed to differentiate between pareses affecting the face, arm and leg. In this
test, subjects are asked to rate their ability to carry out
movements. Different scores were obtained for the face, the
affected arm and the affected leg.
The Benton Test (Benton, 1972) was used to examine
visual short-term memory. This test is sensitive to cortical
lesions. Subjects have to remember and redraw line drawings
of increasing complexity.
The block tapping test (Schellig and Haettig, 1993) was
used to test spatial short-term memory. This test is performed
using an array of small square blocks arranged in a small
rectangular area. The examiner sequentially points to a
number of blocks, and the patient has to repeat the sequence
after a short delay. The complexity of the task (number of
blocks to be sequentially pointed to) is increased until
mistakes occur.
The d2 test (Brickenkamp, 1972), a test of selective
attention, was also administered. Subjects have to carry out
a visual pattern detection task for about 5 min, as fast and
accurately as possible.
In addition, a neglect screening was carried out. The
procedure determines if subjects suffer from a neglect in one
hemifield. It includes marking the middle of lines of different
lengths placed in front of the patient, and pointing to objects
placed on the table, to the patient’s left or right.
Finally, a short version of Oldfield’s (1971) handedness
inventory (50% of the items) was administered. For different
manual activities, e.g. throwing a ball or cutting with scissors,
the subjects have to indicate whether they usually carry them
out with the left or right hand. The patients were instructed
to indicate the hand they had used before the occurrence of
their cortical lesion.

Lexical decision experiment
Stimuli. One hundred and fifty concrete German nouns
and action verbs and 150 pseudowords were chosen as
stimuli. The words included 50 concrete nouns with strong
visual associations (visually related nouns), 50 concrete nouns
with both strong visual and motor associations (bimodal
nouns) and 50 action verbs which caused strong motor
associations (action verbs). Note that most German nouns
cannot be used as verbs and that the use of nouns homophonous to verbs (nouns that are generated from verbs) occurs

quite rarely. The presented words are usually classified as
either nouns or verbs.
The words were matched for frequency of occurrence and
for word length. All words were four to nine letters long.
The average lengths were 6.4 (visually related nouns), 6.2
(bimodal nouns) and 6.6 (action verbs) letters. As revealed
by a t-test, these differences were not significant. All words
consisted of two syllables. All are common words in German
with moderate word frequency. According to the CELEX
database (Baayan et al., 1993) they occur between one
and 50 times per million words. Group averages of word
frequencies were 7.9 (visually related nouns), 8.8 (bimodal
nouns) and 7.3 (action verbs) per million words in standard
text. t-tests failed to reveal any significant between-group
differences in word frequency.
Pronounceable and orthographically regular pseudowords
were constructed by permutating letters within a word or by
exchanging one letter between two words. All pseudoword
stimuli were thus matched for length to the word sample.
All pseudoword stimuli were two syllables long.
Pre-experiment performed to evaluate stimulus words. To
validate our impression that the three word groups were
clearly different in the ways explained above, cognitive
processes elicited by these items were assessed in a preexperiment (cf. Pulvermüller et al., 1999a). The subjects
were asked to rate the stimulus words on five-point scales.
The participants were asked:
(1) whether the words reminded them of visually perceivable
objects or scenes (visual association rating)2;
(2) whether the words reminded them of activities they could
perform themselves (action association rating), and
(3) whether they considered the words as concrete or abstract
(concreteness rating).
Note that a question about motor associations may leave it
unclear whether associations of movement perceptions or
actual actions performed by the subject are to be rated.
Therefore, it was made clear by the instruction that motor
activities performed by the experiment participants were
meant.
Twelve volunteers (monolingual native speakers of
German, aged 20–31 years; mean age 25 years) were paid
for participating in a 1-h session during which they saw
words followed by questions on a computer screen. The
ratings were made by pressing one of five numbered buttons
on the computer keyboard.
Preliminary analyses of the data showed that mean ratings
significantly and strongly differed between the three rating
scales, and that the variances were also different. To yield
equal means and variances on each of the rating scales, the
values were z-transformed. The mean rating on each scale
was therefore 0, and positive or negative numbers indicate
above- or below-average visual and action associations. After
z-transformation, the variance on all scales was 13.
When the values obtained on the scales for action and
visual association strengths were entered into an analysis of

The right hemisphere’s role in action word processing 309

variance, a clearly significant interaction of the word category
factor with the rating scale factor emerged. This was so
for raw values (F(1,11) ⫽ 127.3, P ⬍ 0.0001)4, and for
z-transformed scores (F(1,11) ⫽ 55.7, P ⬍ 0.0001). The ratings
of action associations revealed the highest z-values for the
group of action verbs (0.6), slightly slower values for the
bimodal nouns (0.2) and a clear below-average outcome for
the group of bimodal nouns (–0.8). These numbers document
that the action associations of one of the noun categories
was clearly below average. Post-hoc Scheffe tests further
confirmed these differences in action ratings between the
visually related noun category and both other categories
(P values were ⬍0.0001 for both relevant comparisons).
There was a marginally significant difference between action
verbs and the group of bimodal nouns (P ⫽ 0.05). The
visual ratings revealed reports of clearly stronger associations
for both noun groups (z ⫽ 0.2) than for the action verbs
(z ⫽ –0.4). The Scheffe tests confirmed this (P values were
0.01 and 0.03, respectively). Finally, the concreteness ratings
revealed additional differences between the three word groups
(F(2,22) ⫽ 7.4, P ⫽ 0.007). The outcome here was very
similar to that of the visual associations: nouns were rated
substantially more concrete than verbs (the z-scores were
again 0.2 for both noun categories, and –0.4 for the verbs).
The correlation between visual association ratings and concreteness ratings was significant (r ⫽ 0.62, P ⬍ 0.0001).
The results substantiate the claims that the present set of
action verbs elicits stronger action associations but weaker
visually related associations than the nouns included in the
visually related group. In addition, the results show that what
we call the group of ‘bimodal’ nouns indeed elicits both
strong visual and action associations. Furthermore, there was
good agreement between the concreteness and the visual
ratings for the word groups under investigation.

to respond as fast and as accurately as possible. They were
given ample opportunity to practise with a set of practice
stimuli not used in the subsequent experiment.
The experiment consisted of eight blocks. Each block
contained 36–38 of the 300 stimuli. Between any two blocks
the subjects could decide whether they would like to have a
break. A new pseudo-random sequence of stimuli was made
up for each subject.
During the experiment a fixation cross was shown in the
middle of the computer screen. The subjects were told to
fixate their eyes on this cross. After a delay randomly varying
between 2 and 2.5 s, a warning tone of 800 Hz was presented
for 200 ms; 1000 ms after the onset of the tone, the fixation
cross disappeared and was replaced by a word or pseudoword
stimulus. These stimuli were presented for 130 ms, thus
guaranteeing tachistoscopic stimulation. This shows that we
chose a demanding (reaction time) task. We used this task
to guarantee that both normal control subjects as well as our
patients were challenged so that ceiling effects, that may
mask potential word category differences in simple tasks,
were unlikely. Consistent with this, our healthy controls only
reached around 90% correct responses. The subjects had to
respond during the subsequent 3 s (otherwise trials were
evaluated as incorrect). The stimuli were presented horizontally in capital letters either at the centre of the screen, or,
bilaterally, with two copies of the same word or pseudoword
simultaneously flashed to the left and right visual fields. The
inner angle of the word was 0.9° and the outer angle was
4.9°. The words were thus flashed to the perifoveal region.

Apparatus. Data were collected with an IBM-compatible
Pentium computer. The subjects were seated approximately
50 cm from a 17⬙ computer monitor, with their chin on a
chin rest, and had to fixate the centre of the screen. Two
keys on the computer keyboard were used to collect the
subjects’ responses. One key was labelled with the letter ‘w’
for ‘word’, the other key was labelled with the letter ‘n’ for
‘no word’. The subjects had to press the ‘w’ key with the
middle finger and the ‘n’ key with the index finger of their
right unimpaired hand.

Error scores and response times in the lexical decision task
were evaluated separately for normal controls and for the
two patients with right frontal lobe lesions. In the patients,
χ2 tests were used to assess significant word category
differences on the accuracy measure. Their response times
were submitted to analyses of variance with the factor ‘word
category’ (three levels). The three word categories (visually
related nouns, bimodal nouns, action verbs) were compared
and, in the case of CE with whom three experiments were
carried out, a second factor ‘session’ was added. Only correct
responses were analysed. The error/correctness scores were
also compared between word categories using the χ2 test.
Response time and accuracy data from the control group
were submitted to separate analyses of variance.

Procedure. The entire neuropsychological test battery and
the experiments were usually carried out in three sessions,
each of approximately 50 min duration. During the first two
sessions the experiments were performed and during the third
session the neuropsychological tests were administered. If
the lexical decision task was administered multiply, this was
done in additional sessions following the neuropsychological
examination. Before the experiment the patients were
instructed to decide whether they considered a certain letter
string to be a real German word or a meaningless pseudoword
and to press a button accordingly. The subjects were asked

Results
Data analysis

Neuropsychological assessment
The results of the neuropsychological assessment of the
two patients are shown in Table 1. Age-corrected values
significantly below the average of the age group are indicated
by asterisks.

310 B. Neininger and F. Pulvermüller
Table 2. Error scores and mean reaction times for words and pseudowords,
obtained in two patients with right hemispheric lesions and in control
subjects

GU
CE
Controls

Bilateral
Central
Bilateral
Bilateral
Central

Accuracy score
(% correct)

Mean latencies
(ms)

Words

Pseudowords

Words

Pseudowords

94
57
71
81
92

89
79
63
63
83

992
1068
1029
829
881

1147
1075
1063
919
1046

Table 3. Error scores and mean reaction times for the three word categories,
visually related nouns (viNs), bimodal nouns (biNs) and action verbs
(acVs), obtained in two patients with right hemispheric lesions and in
control subjects

GU
CE
Controls

Patient GU did not show any deficits on the tests administered. This indicates that the tested aspects of attention,
praxia and visuospatial processing and short-term memory
were in the normal range. In addition, he did not give any
indication of an aphasic language disturbance. He scored
zero error points on the Token Test, immediately selected
the correct picture out of four alternatives when presented
with written sentences, and read aloud the paragraph from
the informed consent form without any difficulty.
CE also performed well on the clinical tests, with two
exceptions, however. The visual and spatial short-term memory tests gave evidence of reduced performance. Visual and
spatial memory deficits are frequently associated with lesions
in the right hemisphere. Mild disturbances are unlikely to
affect the performance on a lexical decision task, because
this task does not have a visual or spatial short-term memory
component. And even if these deficits somehow affected the
results on the lexical decision experiment, it would be difficult
to argue that they relate to the category-specific deficits
reported below. Furthermore, the good performance on the
d2 test suggests good selective attention which is a precondition of good performance on any reaction time experiment, lexical decisions included. Language tests and
screenings revealed instant and error-free responses.

Lexical decision task
Table 2 shows the accuracy scores (percentage of correct
responses) and mean latencies of correct responses to words
and pseudowords for patients and controls. In all experiments,
the average responses to words were faster compared with
pseudowords. Also, accuracy scores revealed better performance on words, with the only exception of CE’s first testing
session. Word superiority on the latency measure is a common
finding in the lexical decision task [see, e.g. Mohr et al.
(1996) for a discussion].
The results for the three word categories, visually related
nouns, bimodal nouns and action verbs, are summarized in
Table 3. For the patients, both accuracy and average latency
measures revealed reduced performance on action verbs.
They elicited more errors compared with visually related
nouns (minimal difference 8%) and bimodal nouns. In addi-

Bilateral
Central
Bilateral
Bilateral
Central

Accuracy score
(% correct)

Mean latencies
(ms)

viNs

biNs

acVs

viNs

96
82
74
84
91

98
74
76
86
92

88
14
62
72
94

894 933 1165
1072 1030 1239
1023 948 1136
839 789 865
887 870 897

biNs

acVs

Fig. 4. GU’s mean reaction times for visually related nouns (viNs), bimodal
nouns (biNs) and action verbs (acVs). Significant differences are indicated by
asterisks (P ⬍ 0.05).

tion, the average response times were slowed for action verbs
compared with both other categories. There was no such
striking difference between the two noun categories.
In the healthy controls, accuracy scores and mean latency
data did not indicate differences between word categories.

Patient GU
An analysis of variance showed a significant main effect of
the three-level factor ‘word category’ (F(2,138) ⫽ 13.3,
P ⬍ 0.0001). Additional analyses investigating latency differences between any two of the three categories revealed
significant differences between visually related nouns and
action verbs (F(1,138) ⫽ 23.0, P ⬍ 0.0001) and between
bimodal nouns and action verbs (F(1,138) ⫽ 17.0, P ⬍ 0.0001).
There was no significant latency difference between the
visually related nouns and bimodal nouns. The results are
illustrated in Fig. 4 where asterisks are inserted to indicate
significant differences. In the analysis of error scores, χ2 tests
revealed a significant difference between the two noun
categories and action verbs (χ2 ⫽ 4.8; P ⬍ 0.03). There was
no significant difference between the visually related and
bimodal nouns.
In summary, responses to visually related nouns and
bimodal nouns were significantly faster and more accurate
compared with those to action verbs.

The right hemisphere’s role in action word processing 311

Fig. 5. Mean reaction times for visually related nouns (viNs), bimodal nouns
(biNs) and action verbs (acVs) in all three testing sessions of patient CE.
Significant between-category differences are indicated by asterisks (P ⬍ 0.05).

Fig. 6. Mean reaction times for visually related nouns (viNs), bimodal nouns
(biNs) and action verbs (acVs) in control subjects. There were no significant
between-category differences.

Patient CE
CE was tested three times because the word category difference obtained in the first experiment was so extremely
pronounced that we felt that reproducing this difference
would be desirable: he performed quite well on nouns
(approximately 75% correct responses), but way below
chance on verbs. This suggests that he was unable to recognize
the verbs in this experiment, but could recognize and process
most nouns. We repeated the experiment twice with slightly
altered stimulus presentation. Whereas in the first experiment,
the stimulus words were centred at fixation, they were shown
bilaterally in experiments two and three. Statistical analyses
were performed to test for: (i) the stability of word category
processing differences over experiments; and (ii) a possible
influence of the change in the presentation mode. A threeway ANOVA was conducted on reaction times with the factors
‘session’ and ‘word category’. The results are displayed in
Tables 2 and 3 and in Fig. 5.
The analysis of variance revealed a main effect of the
factor ‘experiment’ (F(2,303) ⫽ 32.7, P ⬍ 0.0001). There
was performance improvement with increasing number of
sessions. Planned comparisons just failed to reveal a significant difference between the first and second experiments
(F(1,303) ⫽ 3.5, P ⬍ 0.06), but significant differences were
found between the first and third experiments (F(1,303) ⫽ 47.5,
P ⬍ 0.0001) and between the second and third experiments
(F(1,303) ⫽ 41.4, P ⬍ 0.0001). Together with the lack of
significant interactions discussed below, this implies that
there was no evidence of significant differences between the
central and the first bilateral presentation, but rather between
the first and second bilateral presentations.
There was a main effect of the factor ‘word category’
(F(2,303) ⫽ 7.2, P ⬍ 0.0008). Planned comparisons showed that
action verbs yielded significantly slower responses compared
with both visually related nouns (F(1,303) ⫽ 5.8, P ⬍ 0.01)
and bimodal nouns (F(1,303) ⫽ 14.2, P ⬍ 0.0002). These
results are illustrated in Fig. 5. When data from the first
testing session were excluded from the analysis, the word
category main effect was still present (F(2,219) ⫽ 6.03,
P ⬍ 0.003). The interaction of the factors ‘experiment’ and
‘word category’ was far from significant. This suggests that

the word category difference did not significantly change
between experiments although performance may have
approached ceiling in the third testing session in this particular
patient. Note that this pattern of results further suggests
that the word category-specific processing differences were
equally present in both presentation modes, central and
bilateral, in the present patient.
The error scores were again investigated using the χ2 test.
In the overall analysis of data from all three sessions, the
differences between the visually related nouns and the action
verbs (χ2 ⫽ 30.9; P ⬍ 0.0001) and between the bimodal
nouns and the action verbs (χ2 ⫽ 29.4; P ⬍ 0.0001) were
highly significant, while there was no significant difference
between the two categories of nouns. When data from the
bilateral sessions 1 and 2 were pooled, a similar pattern of
results arose. The difference between the bimodal nouns and
the action verbs became significant (χ2 ⫽ 5.1; P ⬍ 0.02) as
well as the difference between the visually related nouns and
the action verbs (χ2 ⫽ 3.7; P ⫽ 0.05). The difference
between the visually related and bimodal nouns was far from
significant. The accuracy scores of the first (central) session
alone revealed significantly less accurate responses to action
verbs compared with both visually related nouns (χ2 ⫽ 46.3;
P ⬍ 0.0001) and bimodal nouns (χ2 ⫽ 36.5; P ⬍ 0.0001).
There was no difference between the two noun categories.
Thus, this patient, like GU, gave evidence of reduced
performance on action verbs compared with the other word
categories. In this case, the results could even be shown to
be stable over different presentation modes and with stimulus
repetition.

Controls
An analysis of variance failed to show a significant main
effect of the three-level factor ‘word category’ investigating
latency differences. The results are illustrated in Fig. 6.
Furthermore, a second analysis of variance performed on
error scores obtained from each individual for each word
category did not reveal significant differences.

312 B. Neininger and F. Pulvermüller

Discussion
Two patients with lesions affecting the right frontal lobe
underwent neuropsychological testing and participated in
lexical decision experiments. Although an aphasia test and
additional screening did not reveal any neurological language
disorder, the patients’ performance on a speeded lexical
decision task gave evidence of a category-specific word
processing deficit. Lexical decisions on action verbs were
slowed and less accurate compared with matched visually
related nouns and nouns with both visual and action associations. In one patient, the word category deficit was related
to a right perisylvian lesion primarily involving the inferior
frontal lobe. In the other patient, the underlying cause was a
small lesion in the right pre-motor, motor and somatosensory
areas. Control subjects did not show any word category
deficit. This demonstrates that: (i) right hemispheric lesions
can cause deficits in processing action verbs; and (ii) such
deficits can arise from very focal lesions only affecting a
small part of the pre-motor, motor, and somatosensory cortex.
One may argue that the lack of any significant differences
in the control group was due to the few healthy controls
aged over 65 years (n ⫽ 3), because they might have been
particularly slow and inaccurate, thereby masking possible
differences between stimulus types in younger group members. However, removal of these subjects did not change the
general picture. Mean accuracy scores and response times
were still similar for the three word categories under investigation. Also, in earlier studies (Pulvermüller, 1999a, b)
employing younger subjects (around 20–30 years of age),
we could not find evidence for significant differences in
response times or accuracy scores of lexical decisions related
to the present word categories. It is therefore not plausible
that the absence of significant behavioural differences
between word categories in the present control data is related
to the age of healthy participants.
In this study, word category differences in neurological
patients were revealed by a lexical decision experiment. In
earlier work (e.g. Warrington and McCarthy, 1983, 1987;
Warrington and Shallice, 1984; Damasio and Tranel, 1993;
Sartori et al., 1993; Hillis and Caramazza, 1995; Humphreys
et al., 1999; Perani et al., 1999), category-specific deficits
were obtained in other tests, for example naming or verbal
definitions of the meaning of words. Impaired performance
on these tasks can, in principle, be explained by different
cognitive deficits, including retrieval of word forms, semantic
processes, or the analysis of the visual images of to-benamed objects. In contrast, a lexical decision task can be
carried out based on the orthographic and phonological
knowledge of words included in the lexicon. Strictly speaking
and from a theoretical point of view, no semantic knowledge
is necessary for deciding whether a letter string is a word or
not. The present results can therefore be interpreted as
evidence that the retrieval of the word forms, not only the
retrieval of semantic knowledge associated with the word
form, is differentially affected in our patients. Thus, the
present results argue in favour of a core linguistic deficit.

It may be that the category-specific deficit in action verb
processing crucially depends on the processing demands of
the task applied. Subjects had to perform fast button presses
to judge whether words or pseudowords were presented and
stimuli were shown only briefly. It may therefore be that
category-specific deficits in patients with right hemispheric
lesions can only be revealed by demanding psycholinguistic
testing. The patients’ reports were consistent with this. Asked
about possible language problems in everyday life, both
patients put great emphasis on the fact that they never noticed
such problems. Also, the patients were asked after the
experiment whether they had ever noticed a difficulty in
using or understanding words related to actions, but both
gave negative answers. Together with the perfect performance
on clinical language tests and screenings, and consistent with
our clinical impression when communicating with them, this
suggests that there were no obvious difficulties in everyday
life language use,5 although category-specific deficits were
clearly documented by the demanding reaction time
experiments.
The present results replicate the findings reported by
Pulvermüller (Pulvermüller et al., 1998) who found impaired
performance on action verbs compared with visually related
nouns. In this earlier study, data obtained from patients
with right hemispheric lesions were contrasted with the
performance of a control group matched for age and level of
education. A significant interaction of the word category
factor with the between-group factor revealed more errors
on action verbs than nouns in the patients, but a tendency in
the opposite direction in the controls. Consistent with the
earlier results, the control group included in the present study
failed to show word category differences in the lexical
decision task.
We note that the methods slightly differed between the
control study and most experiments performed with our two
patients. Words were presented in the centre of the video
screen in the experiment with controls, but bilaterally in most
experiments with the patients. However, we emphasize: (i)
that the data from patient CE indicate that, at least in this
patient, the category deficit was present irrespective of the
mode of presentation; and (ii) that there is no theory-related
reason why a change of the presentation mode should cause
a word category-specific processing deficit in normal controls.
One may still claim that a word category deficit may arise
in healthy individuals if they are bilaterally presented with
redundant stimulus words. We should, however, emphasize
that earlier studies did not find such category specificity
related to bilateral presentation if stimuli were, as in the
present experiments, matched for length and word frequency
(Mohr et al., 1994). As an additional argument, we should
remind the reader that word and pseudoword stimuli were
centrally presented in both the first experiment performed
with patient CE and in our earlier group study. This group
study performed with nine patients suffering from lesions
affecting different parts of the right frontal lobe revealed the
same word category difference between action verbs and

The right hemisphere’s role in action word processing 313

visually related nouns that was apparent in the two patients
studied here with bilateral stimulation. Therefore, the word
category-specific deficit apparent from lexical decisions
appears independent of whether stimulus presentation was in
the centre of the screen, or laterally, with two redundant
copies of the same word being presented to the left and right
of fixation. In future studies, it will be important to compare
a larger group of patients with right hemispheric frontal
lesions and matched neurological control patients receiving
bilateral stimulus presentation.
In contrast to our earlier group study, we found significant
word category differences not only for the accuracy measure,
but also in latencies. Verbs were responded to less accurately
and more slowly compared with nouns in both patients.
Furthermore, the effect could be replicated twice in one
of the subjects. This consistency of results over different
measures, patients and experimental sessions reveals the
robustness of the effect.
The present study overcame one shortcoming of our earlier
group study and allows us to attribute the word category
deficit to particular lesion sites. The data obtained from
patient GU demonstrate that a pronounced specific processing
deficit for action verbs can arise from lesions in the nondominant right hemisphere. In this case, the lesion affected
the perisylvian areas with strongest involvement of frontal
sites. Strictly speaking, the data from this patient alone would
not be sufficient to draw conclusions on the relevance of
action-related cortices, because the lesions in temporal or
parietal areas could also have contributed to the linguistic
impairment. However, we wish to emphasize that based on
the group data the conclusion of a specific contribution of
areas in the right and non-dominant hemisphere to action
verb processing appears to be safe.
CE’s word category-specific deficits arose from a much
more focal lesion. Only a small portion of the right premotor, primary motor, and primary somatosensory cortices
were lesioned. In addition, white matter was affected. This
allows for a strong conclusion on the relevance of these areas
to action verb processing. However, one may argue that this
patient was not right handed, and it is well known that,
compared with right handers, atypical hand preference is
more frequently associated with right hemispheric language
dominance. However, several studies (e.g. Milner, 1974;
Bryden et al., 1983) found that approximately 70% of
clear left handers exhibited normal, that is, left hemispheric
language dominance, while in only approximately 20% of
these subjects was the right hemisphere dominant for language. (The rest did not show language dominance.) In this
context, we should re-emphasize that CE was far from being
a typical left hander. His scores on the Oldfield inventory
revealed only a minor preference for the left hand (decile L3
according to Oldfield, 1971) and therefore it appears more
appropriate to consider him as ambidextrous. Therefore, the
probability of right hemispheric language dominance in CE
appears to be low (and it is non-zero even in strict right
handers). Thus, we conclude that the cause of CE’s word

category-specific deficit was a small lesion in the pre-motor,
motor and somatosensory areas of his right hemisphere which
was most likely not dominant for language.
By using a neglect screening procedure, we tried to make
sure that our patients did not suffer from a neglect that could
possibly influence the results. In addition, the stimuli were
presented bilaterally so that, even in the case of a left-sided
perception deficit (e.g. extinction), the stimuli should have
reached the intact visual hemifield. One may, nevertheless,
propose that the category-specific deficit could be caused by
an object-centred form of neglect. However, we believe that
this is not likely. Tipper and Behrmann (1996) state that, in
their study, object-centred forms of neglect appeared to be
present primarily in patients with clearly manifest and severe
neglect. Farah et al. (1990) found in their study of patients
with manifest neglect, that the neglected hemifield was not
defined with respect to an object-centred frame of reference.
Accordingly, object-centred forms of neglect appear to occur
rarely and only very rarely in patients who fail to show
obvious signs of the presence of a neglect. Our patients failed
to show such signs and, therefore, we considered it unlikely
that they suffered from object-centred perception deficits.
As reported in Materials and methods above, concreteness
ratings performed on the word groups used in the present
experiments revealed significant differences between the
three categories. These concreteness ratings significantly
correlated with the ratings of visual association strength
(r ⬎ 0.6). One may, therefore, ask whether the word category
deficit seen in the present patients can be explained by
the concreteness of the words tested. Earlier studies have
substantiated the hypothesis that the right hemisphere primarily contributes to the processing of concrete words. For
example, physiological brain responses to abstract words
have been found to be strongly lateralized to the left, whereas
more concrete words show less lateralization (Neville et al.,
1992; Kounios and Holcomb, 1994; Pulvermüller et al.,
1995). In addition, several features of agrammatic speech
can be explained by a stronger contribution of the right
hemisphere to the processing of concrete content words
which appear to be retained in patients exhibiting this deficit
(Pulvermüller, 1995). If the right hemisphere is, in general,
most relevant for processing concrete words, lesions therein
should primarily affect the most concrete words. However,
the highest visual association ratings and also the highest
concreteness scores were obtained for our noun categories.
Therefore, the right hemisphere concreteness hypothesis
predicts an affection of noun, rather than verb, processing
after right hemisphere damage. This contrasts with the present
results where the word category exhibiting the lowest scores
on visual association and concreteness ratings, the action
verbs, was most severely affected. Thus, while the present
results are in good agreement with the neurobiological model
of word processing, they actually falsify an unspecific right
hemisphere concreteness hypothesis. To the extent that ‘concreteness and imagery are so highly correlated (r ⫽ 0.83)
that they can be taken as essentially defining the same

314 B. Neininger and F. Pulvermüller

variable’ (Paivio, 1971, p. 201), it appears feasible to conclude
that the present pattern of results is also not fully consistent
with the proposal that the right hemisphere is, in general,
involved in imagery-related processes. It would be necessary
to distinguish between contributions of posterior right hemispheric areas to visual imagery and a possible role of right
frontal areas in the imagery of actions.
The data are compatible with the view that supplementary
language areas for action verbs exist in the right frontal lobe.
These supplementary language areas may be related to the
storage of action associations of these word types. The
neuronal circuits organizing the word form knowledge
and that of the action-related knowledge should, as a
Hebbian perspective on language would suggest, be tightly
connected and functionally inter-dependent (as discussed in
Pulvermüller, 1999). As pointed out in the Introduction, a
focal lesion in the relevant areas in the frontal lobes should
therefore result in a category-specific deficit affecting actionrelated word types more than words with significantly less
action associations. The prediction is met by the present data
on action verbs.
Our results are in good agreement with the neuropsychological literature on verb processing deficits. Frontal lesions
in the dominant left hemisphere were sometimes found to
lead to aphasias in which deficits in processing verbs dominated over the processing deficits for other content words
(Miceli et al., 1984; Damasio and Tranel, 1993; Daniele
et al., 1994). For example, Bak and Hodges (1997) investigated three patients with motor neurone disease, an illness
affecting cortical motor areas as well as other parts of the
frontal lobes of both hemispheres. All three patients had a
rapidly progressing aphasia and a frontal type dementia.
The authors used a test of verb and noun naming and
comprehension adapted from Berndt et al. (1997), with nouns
and verbs matched for lexical frequencies. They found that
there was a consistent advantage of nouns over verbs in
comprehension and production. This was replicated in a more
recent study (Bak et al., 2001). The present results are
consistent with this result and further confirm the role of
frontal cortices in verb processing.
The present study extends the earlier finding in patients
with aphasia in three important ways: first, we proved that
the verb-specific processing deficit is independent of the
presence of an overt aphasia: both patients participating in
the present study were without clinical symptoms of an
aphasic language disturbance, and their error-free performance on the Token Test illustrates this in an impressive
manner. Second, it could be demonstrated that lesions in the
non-dominant hemisphere can cause verb-specific deficits.
Third, it could be shown that even a small lesion outside the
perisylvian core areas, which, in patient CE, affected a small
part of the motor, pre-motor and somatosensory areas, can
lead to specific and pronounced processing disadvantages for
action verbs.
The results are consistent with the view that neural systems
devoted to the programming of actions are interwoven with

the representations of action-related word forms, so that the
two parts of the distributed representation, the primarily
left hemispheric phonological/orthographic and the bilateral
semantic part, are mutually dependent (Pulvermüller, 1999).
This has been proposed based on the Hebbian cell assembly
framework and correlation learning, which is well known to
be an important function of the cerebral cortex. If word form
and meaning-related actions or perceptions are frequently
processed at the same time, the neurones involved will
frequently fire together and will therefore also wire together,
thus yielding distributed representations by which word forms
and meanings are held together. Because the meaningrelated processes probably involve neuronal firing in both
hemispheres, the relevant distributed word representations
have been postulated to involve neurones in both hemispheres.
Therefore, lesions in the action-related semantic areas in both
hemispheres should have the potential to cause specific
deficits in accessing word forms characterized by actionrelated meanings. We interpret the present data as evidence
for a core linguistic deficit in accessing word forms and
propose that areas involved in the programming of actions
and thus relevant for the storage of the meaning of action
words are necessary for the proper access to the forms of
action verbs. In other words, not only lesions in core language
areas, but, in addition, lesions in supplementary language
areas involved in category-specific semantic processing can
have an effect on the processing of word forms.
However, one may object that the data obtained for the
bimodal nouns are not consistent with this view. These words
[many of which were tool names, such as the German noun
‘Hammer’ meaning ‘hammer’ (noun) in English] elicit strong
action associations, although our patients processed them
equally well as visually related nouns not related to actions.
This falsifies the strong semantic hypothesis as detailed in
the introduction above. One may therefore conclude that the
lexical or grammatical difference (noun versus verb), rather
than a semantic difference between word categories, best
explains the present pattern of results consistently revealed
by both patients. The problem with this proposal is that no
ready explanation would be available as to why the right
frontal lobe should play a specific role in the processing of a
category that is grammatically (but not semantically) distinct.
However, we wish to emphasize that there is an alternative
possibility, namely that not all words exhibiting associations
of actions are equally vulnerable, but that a second precondition must be met before a behavioural degradation can
be measured. According to the weak semantic hypothesis
formulated above, only words primarily characterized by
action associations would be vulnerable. This is based on
the idea that a word with strong bimodal or even multimodal
associations is realized in the cortex by a cell assembly
including many neurones in all areas related to its referential
meaning (e.g. visual and motor). Such very large and widely
distributed networks may be less vulnerable to focal lesions
and, thus, would explain why nouns with both strong action
and strong visual associations still yielded relatively good

The right hemisphere’s role in action word processing 315

performance in the present experiments. Also, action associations were somewhat weaker for bimodal nouns compared
with action verbs (see Materials and methods). Therefore,
their networks may include less action-related neurones than
the networks representing action verbs. This may provide an
additional putative explanation of why action verbs, rather
than multimodal nouns, suffered most.
We conclude that both the lexical hypothesis and the weak
semantic hypothesis are consistent with GU’s and CE’s
performance patterns. Future research aimed at deciding
between the two remaining views is now needed.

Conclusions
The present double case study has two main results: (i)
lesions restricted to the non-dominant right hemisphere and
not leading to an overt aphasia can lead to a pronounced
word category-specific processing deficit; (ii) such a deficit
can follow very focal lesions in the right hemisphere only
affecting pre-motor, primary motor, and primary somatosensory areas. Category-specific deficits were revealed by finegrained psycholinguistic testing using a speeded lexical
decision task. Our results are consistent with the view that
the right hemisphere not only contributes to but, in addition,
is necessary for the core language function of access to
lexical representations and phonological/orthographic word
forms, and that the right frontal lobe is particularly relevant
for the processing of words from the category of action
verbs. Our findings support a neurobiological model of
language according to which word processing is based on
cell assemblies distributed over both hemispheres whose
right hemispheric parts are related to word meaning.

Acknowledgements
We wish to thank Thomas Bak, Helen Bird, Thomas Elbert,
Ernst Gut, Bettina Mohr, Willi Nagl, Karalyn Patterson,
Brigitte Rockstroh, Paul Schönle, Katrin Zohsel and three
anonymous referees for their help, comments and suggestions
at different stages of this work. Special thanks go to Willi
Nagl and Helen Bird for their advice regarding statistical
analyses and to Ernst Gut who helped us to evaluate the
MRI scans. This research was supported by grants Pu 97/ 5-2
and Pu 97/ 10-1 from the Deutsche Forschungsgemeinschaft,
by an AFF-grant from the University of Konstanz, and by
the Lurija-Institute for Rehabilitation Research, Kliniken
Schmieder, Allensbach.

Notes
1. These diagrams are meant to illustrate the putative
neuronal basis of the differential involvement of supplementary language areas (here: in frontal and temporal
lobes) to word category-specific representations and processing. They should not be taken to suggest that any of
the supplementary language areas exclusively organizes

one word category. Rather, the stronger and weaker
correlation of particular types of words with visual stimuli
or actions is likely to be reflected in stronger connection
to and, therefore, a larger number of frontal versus
occipitotemporal neurones included in the respective cell
assemblies.
2. We suggest that the rating of visual associations yields
results similar to those of imageability.
3. The numbers therefore cannot (and are not intended to)
demonstrate the absence of associations in one modality.
For example, the action verbs, which scored substantially
below average (z-score ⫽ –0.4) on the visual ratings, may
still elicit some visual associations. In the context of the
present study, the category-related differences in the
associations are of interest.
4. The tests on z-transformed values proved more conservative and we will therefore only report them below.
5. The deficit may still affect everyday language conversation
in some way, although this would be rather difficult to
measure.

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Received on 1 February, 2000; resubmitted on 30 March, 2000;
accepted on 3 November, 2000

The right hemisphere’s role in action word processing 317

The right hemisphere’s role in action
word processing: a double case study
B. Neininger and F. Pulvermüller
Abstract
Word category-specific deficits were investigated in two patients with right
hemispheric lesions and hemiparesis affecting the left extremities. Words from
three categories, action verbs, nouns with strong visual associations and nouns
with both strong action and visual associations, were presented in a lexical
decision task. The stimulus categories were matched for word length and
frequency. In both patients, responses to action verbs were slowed and/or less
accurate compared with the other word categories. This was so even in the
patient with a minor lesion in the motor, pre-motor and somatosensory areas
of the hand representation. Control subjects did not show category differences
when tested with the same stimulus materials. These results are consistent
with the view that the cortical areas involved in the programming of body
movements, even those in the hemisphere not dominant for language,
specifically contribute to and are necessary for the processing of words
referring to such movements. As an alternative, the affected brain areas may
be of particular relevance for the processing of words from the lexical category
of verbs. The results are consistent with a brain model of language based on
Hebb’s cell assembly concept.

Journal
Neurocase 2001; 7: 303–17

Neurocase Reference Number:
O225

Primary diagnosis of interest
Right hemispheric ischaemia, hemiparesis

Author’s designation of case
GU, CE

Key theoretical issue
d The cortical areas involved in the programming of body movements, even

those in the hemisphere not dominant for language, specifically contribute
to and are necessary for processing of words referring to such movements
Key words: category-specific deficit; cell assembly; lexical category;
neurolinguistics; noun; word processing; semantic category; verb

Scan, EEG and related measures
MRI

Standardized assessment
Token Test, Aachen Aphasia Test, Benton Test, block tapping test, d2 test,
Oldfield’s handedness inventory

Other assessment
Lexical decision task, apraxia questionnaire, paresis screening, instrument,
neglect screening

Lesion location
d Motor, pre-motor and somatosensory areas of the right hemisphere (CE);

perisylvian areas of the right hemisphere (GU)

Lesion type
Ischaemic insult

Language
English