cognition, 36 (1990) 129-153
Processing distinctions between stems and affixes:
Evidence from a non-fluent aphasic patient*
LORRAINE K. NLER
SUSANBEHRENS
HOWARD COBB
University of Cambridge
WlLLlAM MARSLEN-WILSON
MRC Applied Psychology Unit,
Cambridge
Received June 2, 1989, final revision accepted February 19, 1990
Abstract
Tyler, L.K., Behrens, S., Cobb, H., and Marsten-Witson, W., 1990. Processing distinctions
between stems and affixes: Evidence from a non-fluent aphasic patient. Cognition, 36: 129-153.
In this paper, we study the ability of a non-fluent aphasic patient, BX, to
comprehend morphologically complex words when they appear in utterance
contexts. Wefirst establish that he is insensitive to the contextual appropriateness
of both derived and inflected words. In a further experiment we show that he
has no difficulty processing the stems of complex words and conclude th-zt his
problem is with the bound morphemes themselves. We then ask whether this
problem is due to his inability to access either the phonological form of a
morphologically complex word or its semantic andlor syntactic content. We
find that only the access of semantic and syntactic content is impaired. We
conclude from these six studies that: (a) BN presents a counter-example to the
claim that non-fluent patients have particular dificulty with those aspects of
morphology which have a syntactic function; (b) BN processes both derived
and inflected words by mapping the sensory input onto the entire full-form of
a complex word, but the semantic and syntactic content of the stem alone is
accessed and integrated into the context. The semantic and syntactic implications of the suffix are never evaluated. This implies separate representation of
the stems and sufSixes of some types of morphologicully complex words.
*We thank Paul Warren for his help with these experiments. This research was supported by an MRC
?ragramme grant to L.K.T.and W.M.W. Requests for reprints should be addressed to Lorraine K. Tyler.
Department of Experimental Psychology. University of Cambridge, Downing Street, Cambridge CB2 3EB.
U.K.
0010-0277/90/$8.00 O 1990-Elsevier Science Publishers B.V.
130
L.K. Tylar at al.
Introduction
There are a number of reports in the literature of aphasic patients who have
particular problems in producing morphologically complex words (e.g., DeVilliers, 1978; Goodglass & Berko, 1960; Goodglass, Gleason, Ackeman, &
Hyde, 1972; Miceli & Caramazza, 1987). English-speaking patients of this
type rarely spontaneously produce morphologically complex words and also
tend to omit the free-standing grammatical morphemes (such as "the" "and"
"but"). Furthermore, they are less likely to produce inflected than derived
words. Problems with morphologically complex \vords show up even more
clearl;. in the spontaneous speech of patients who are native speakers of
languages like Italian and Hebrew, which have a richer inflectional system
than English. Although Italian and Hebrew patients produce inflected words
(presumably because an uninflected root is a non-word in these languages),
the inflections tend to be inappropriate for the context (Grodzinsky, 1984;
Miceli & Caramazza, 1987).
There are indications that the same kind of difficulty with morphoZogically
complex words also occurs in comprehension, although the data here are
much more sparse (e.g., Eling, 1986; Patterson, 1979; Tyler & Cobtb, 1987).
Although most of this research does not distinguish inflected from derived
words, the studies that do (e.g., Tyler & Cobb, 1987) reveal the same kind
of poor performance for inflected words in comprehension as in production.
Although it is rarely the case that such patients only have problems with
the closed class morphology, it has been claimed that difficulties with this
particular type of linguistic element is at the heart of their language disorder
because of the syntactic role which the closed class morphology plays in many
languages. Free-standing grammatical morphemes and the inflectional inorphology, in particular, contribute to the construction of a syntactic representation of an utterance (e.g., Anderson, 1982). The ciaim is that agammatic
patients have problems with these linguistic elements because they do not
have "knowledge of the structural roles played by grammatical markers ...
(and) ... they are thereby unable to use these items as markers of phrasal
constituents" (Cooper & Zurif, 1383).
This pattern of impaired performance is consistent with models of the
unimpaired processing system, such as Garrett's production model (1980), or
l the structure of the lexicon, which
Miceli and Caramazza's (1987) m ~ d eof
stress the functional relationship between the closed class morphology and
the syntactic structure of an utterance. In Garrett's model, for example,
function words and grammatical morphemes are inserted into the sentence
frame at the positional level so as to define the grammatical structure of an
utterance. This accounts for the frequently observed CO-occurrenceof syntac-
Processing distinctions between srems and a m e s
131
tic and morphological deficits in "agrammatic" patients (but see Berndt &
Caramazza, 1980, Goodglass & M e n , 1985; Martin, Blossom-Stach, &
Feher, 1989). Errors in this stage of the process result in two types of errors
involving affixes - omissions and substitutions -which are the types of errors
found in "agrammatic* speech.
For production deficits involving closed class morphemes, theory and data
neatly converge. However, the situation is not quite so clear-cut when we
consider comprehension deficits. There is little evidence bearing directly on
the claim that when patients have problems in comprehension which involve
morphologically complex words, it is because they have a general syntactic
deficit. This is because there are no studies (with the exception of Lukatela,
Crain, & Shankweiler, 1988; Tyler & Cobb, 1987) testing the comprehension
of bound grammatical morphemes in sentence contexts. Instead, experiments
typically involve presenting morphologically complex words in isolation usually for the patient to read (Eling, 1986; Patterson, 1979). The only work
which has examined the processing of grammatical markers in context has
focused on the free-standing morphemes (e.g., Goodenough, Zurif, & Weintraub, 1977; Grossman, Carey, Zurif, & Diller, 1986). This neglect is surprising, since the only way to determine whether a patient can exploit the syntactic (or semantic) properties of a bound morpheme - whether an inflected or
derived form - is to place it in a context which allows the functional significance of those properties to have an effect. This means that the morphologically complex word should appear in a sentential context rather than in an
unstructured word list.
However, to determine whether a patient has problems comprehending
morphologically complex words, we have to do more than just look at his or
her difficulty in processing such words when they appear in sentential contexts. We have to try to tease apart the possible underlying causes of the
problem. This can be complex because there are a number of ways in which
the piocess of comprehending a derived or inflected word can be disrupted.
We assume here a three-stage process. The first stage involves mapping the
senwry input onto mental representations of the plrcse!ogca! farm of a
worct. In the absence of any data to the contrary, we assume that this process
is the same for both simple and suffixed words - that is, the sensory input is
mapped onto the entire form of the word. The second stage occurs after these
form representations have been activated. This is when the syntactic and
semantic properties of the word (i.e., its "lexical content") are accessed. The
process of accessing this information may differ, depending on whether the
meaning of the word represented in a decoinposed or whole form in the
mental lexicon (e.g., Butterworth, 1983; Stemberger & McWhinney, 1986).
The third stage is when the semantic and syntactic properties of a morpholog-
132
L.K. Tyler et al.
ically complex word are used in parsing and interpretation. Although it is
possible in principle to distinguish between the access of content and its use
in sentence interpretation (stages two and three), in practice this is very
difficult and the experiments reported in this paper do not do so.
In principle, patients may have problems with any of these stages. First,
they may have difficulty mapping the sensory input onto mental representations of lexical form. This may be a general problem, involving both morphologically simple and complex words, or it may be confined to complex
words. Second, they may have no problems with form mapping but the access
of lexicd content may be impaired. They may be unable to process the syntactic andlor semantic proporties of morphologically complex words - either
because they are unable to access the component morphemes, or combine
them appropriately. Third, although they uay be able to access the content
of morphemes, they may be unable to use them for parsing and interpretation. To further complicate the picture, deficits in the ability to access either
lexical form or lexical content may bd confined to either derived or inflected
words.
To try to separate out these various factors, we carried out a series of
experiments on a non-fluent aphasic patient, BN. These studies focused on
invofved in comprehending morphologically
different aspects of the
comp!ex words. The first study was designed as a general test of BN's ability
inflected and derived words i h e n they appear in sentential conto
texts. Since he performed poorly in this experiment, we then asked whether
this was due to his inability to access the phonological form of such words,
oi to his inability to access their semantic andor syntactic content. To answer
these questions, we designed a series of studies in which morphologically
complex words were either heard in an unstructured list of words or appeared
in different kinds of sentential contexts. We designed the experiments so as
to be able to tease apart BN's ability to process inflectional and derivational
affixes as opposed to either the full-form of an affix-bearing word or its stem.
We will first of all present a clinical profile of BN, including the results of
standard neuropsychological tests. Then we will report data from a series of
comprehension tests which focus specifically on his ability to process morphologically complex words.
The patient
BN is a 44-year-old male native speaker of British English (born in 1944)
who, in 1984, suffered a left hemisphere cerebrovascular accident (CVA).
He is right-hand dominant with no appreciable hearing loss (mean hearing
Processing distinctions between stem and afFrs
133
loss of 6 dB). No brain scan information is available for him. RN has a right
side weakness and a non-fluent aphasia, as determined by assessment on the
Boston Diagnostic Aphasia Examination (BDAE; Gooddass & Kaplan,
1972). Subtests of production abilities on the BDAE show LN's speech to be
impaired in fluency, with melody, phrase length and gramma'ical form all
below normal levels.
We first tested BN one year after his stroke. His speech output was effortful and primarily consisted of an unstructured string of short noun phrases
and very few verbs. Most of the words he produced were morphologically
simple. He rarely produced an affixed word - whether inflected, derived,
suffixed or prefixed. A sample of his speech is given below.
BN (describing cookie theft picture from BDAE):
Cookie ... boy ... eh yes and girl ... yes ... school ... eh ... cold ... taps ...
plate and saucer.
His memory capacity, as measured by digit span and digit matching tasks
(where two separate digit strings were read to him and he was asked to
indicate whether they were the same or different) was slightly below normal.
He could only accurately recall or match up to four digits.
BN was tested on various standard tests to determine whether his comprehension was normal. On the auditory comprehension sub-tests of the
BDAE, his performance suggested that he only had a slight cornprehension
deficit. He made no errors on the word discrimination and body p r t identification sub-tests, and on the commands and complex ideational material subtests he scored with 75% accuracy. On the Token Test (De Renzi & Faglioni,
1978). his performance was severely impaired (31% correct). Finally, when
he was tested on the Test for the Reception of Grammar (TROG; Bishop,
1982), which is a sentencetword-picture matching task, he made no errors in
matching a spoken word to a picture. He was also very accurate on the
sentence materials - including passives. The results of these auditory comprehension tests suggest that BN has some prob!ems in comprehending
spoken language, but they do not specify the precise nature of the problem.
We now describe the experiments we designed to test his comprehension of
morphologically complex words.
...
Experiment 1: Derived and inflected words in context
This study was designed as a general test of BN's ability to process inflected
and derived words in sentence. contexts (for a more detailed description of
the materials and design see Tyler & Cobb, 1987). We had BN listen to pairs
134
L. K. Tyler et al.
of sentences where the second sentence of each pair contained a derived or
inflected word which was immediately followed by a target noun (the word
"cook in Table 1, which gives an example set of stimuli). For the test words,
there was always a phonologically transparent relationship between the stem
and the affix - that is, the affix did not cause phonological changes to the
stem.
The test word (italicised in the examples below) was either appropriate for
the prior context. In the case of the contextually inappropriate test word, the
sentence up to and including the stem was always appropriate. The form of
the suffix determined whether the word-form as a whole was appropriate or
inappropriate for the context. We established the appropriateness or inap
~ronriatenessof the test word bv means of h re-tests (see Tvler & Cobb. 1987,
#orhetails). The frequency of h e appropAste and inapp;opriate test.words
were matched as closelv as ~ossible.The median freauencv of the sets of
appropriate and inappropriate inflections were 14 a n d i l , r~spectively,and
the median freauencv of the aooro~riateand inaoorooriate
.. . derivations were
11 and 6, resp&tive$ (~rancis& ~ucera,1982).
Table 1.
E.~perimenrl: Example stimuli
- --- ----- -Derivations
1.
2.
3.
1.
2.
3.
--
Appropriate:
Sarah could not understand why John used so much butter. He was the most wasteful
cook she had ever met.
Inappmpriate:
Sarah could not understand why John used so much butter. He was the most wasteage
cook she had ever met.
Non-word:
Sarah could not understand why John used so much butter. He was the most wasrely cook
she had ever met.
Appropriate:
I have to be careful when eating ice-cream. It often causes pain in my loose filling.
Inappmpriate:
I have to be careful when eating ice-cream. It often causing pia in my loose filling.
Non-Word:
I have to be careful when eating ice-cream. It often c a d y pain in my loose filling.
Processing distinctions between stems and affixes
135
In a final condition, we had a test word which wzs a non-word comprised
of a real word stem and suffix (always a derivation), but illegally combined
(e.g., mixly, washness). This condition was included in case BN showed no
difference between the contextually appropriate and inappropriate words.
There were 21 derived and 24 inflected test words. These were pseudorandomly interspersed with 43 filler items designed to obscure the regularities
of the test items. We constructed three lists of materials from these test and
filler items. Each list contained an equal number of items in each of the
appropriate, inappropriate and non-word conditions, as well as the total set
of fillers. Six practise items preceded the test materials. The three versions
were recorded by a female native speaker of English at a normal conversational rate. We then placed timing pulses at the onset of each target word.
These were located on the non-speech channel of the tape and could not be
heard by the listener. They functioned to initiate a digital timer which was
stopped when the subject pressed a response button
Because we were interested in BN's ability to integrate the syntactic and
semantic implications of the suffix into the representation of the sentence as
it is being constructed, we used the word-monitoring task. In this task, the
subject hears a spoken sentence containing a target word, which is specified
in advance, and has to press a response key as soon as the word is identified.
Reaction times (RTs) to respond to the target word are measured from word
onset. In our materials, the target word immediately followed the inflected
or derived test word. RTs in the appropriate condition constitute the baseli~2
condition against which we can evaluate RTs in the other two conditions. ir'
th= syntactic and semantic implications of morphologically complex words
are immediately integrated into the sentence context, then RTs to a target
word which follows a cxntextually appropriate suffixed word should be faster
than those following contextually inappropriate test words. To the extent that
this effect differs for inflected and derived words, then the difference between
RTs in the appropriate and inappropriate conditions will vary.
Apart from BN, we tested a group of 23 subjects (ranging in age from 20
to 37 years). Each of the control subjects was tested or-,sne ver^J:nn of the
materials, whereas BN was tested on all three, with each testkg session
separated by an interval of one month. The w.itrol subject< show an immediate effect of the contextual appropriateness of Lie affixed word
(MinF1(2,112) = 36.7, p < .001 for the three conditions). They are slower
to respond to a target word when it follows either a contextually inappropriate
affixed word (289 ms) or a non-word (322 ms) than when it follows a morphologically complex word which is contextually appropriate (222 ms). RTs
in these three conditions were significantly different from each other (at the
.O1 level or beyond) on the Newman-Keuls statistic, using the MinF error
136
L.K. Tyler er al.
term. The same pattern of results was f ~ u n for
d both the derived and inflected
words. This can be seen in Table 2, which shows the mean KTs in the three
experimental conditions for derived and inflected words separately.
BN's RTs were slower than those of the control subjects (BN: mean RT
= 478 ms; controls = 278 ms). This slowing down of RTs is frequently observed after brain damage (Benton & Joynt, 1959). More importantly, his
pattern of RTs were very differsnt from those of the control group, as can
be .een in Table 2. An ANOVA showed that his monitoring latencies were
not affected by either the contextual appropriateness of the suffixed word,
(F(2,42) = 1.362, F = .26), or of the non-word. And this was the case for
both derived and inflected words. None of the differences between the various experimental conditions were significant (on either the Newman-Keuls
statistic or the t-test).
We used the control group data to calculate the confidence limits for the
differences between (a) the appropriate and inap~ropriateconditions, (b) the
appropriate and non-word conditions and (c) the inapprooriate and non-word
conditions for the derived and inflected sets separately. 11 the size of BN's
difference scores is outside these limits, this is additional evidence that his
performance differs from that of the control group. For both the derived and
inflected forms, the size of the three sets of differences for BN was outside
the confidence limits for the control group (p < .OS).
These results clearly establish that BN is not sensitive to the contextual
appropriateness of the inflected or derived test words, nor to the illegal combination of stem suffix in the non-words. Before exploring possible explanations for this insensitivity in greater detail, we first of all wanted to rule out
the possibility that BN's poor performance was specific to the particular task
we were using - the word-monitoring task. To evaluate this possibility we
tested BN on the same materials, but this time we used a task which is
standardly used in aphasia research - the gramnaticality judgement task and which patients who, like BN, are classified as agrammatics have no probTable 2.
Mean RTs (ms)for control subjects and BN
Controls
Derivations
Inflections
Appropriate
Inappropriate
Non-word
218
231
286
295
319
322
545
434
489
458
526
471
BN
Derivations
Inflections
Processing distinctions between stems and offires
137
lems with (Linebarger, Schwartz, & Saffran, 1983). This is a task in which
the patient is asked to indicate, after hearing each sentence, whether it is an
acceptable sentence in their language.
We tested BN and a group of control subjects on the grammaticality task.
The performance of the control subjects was almost perfect in all conditions
(ranging from 92% to 98%). However, BN's performance was very poor. He
only correctly rejected 10% of the contextually inappropriate sentences and
33% of the sentences containing non-words, and he was equally bad with
derived and inflected words.
The results of the grammaticality judgement task' show that BN's insensitivity to the contextual appropriateness of a suffixed word in the monitoring
task was not merely due to some peculiarity with the task or to some special
difficulty he had with it. The results of both tasks together suggest that BN
has problems evaluating the implications of both inflectionsl and derivational
suffixes with respect to the sentential representation. This is why he is insensitive to their contextual appropriateness and why he is not affected by suffixed non-words.
The next question we asked was whether this problem is specific to morphological affixes or whether it is part of a general problem which BN has in
relating lexical contents to sentential representations. That is, does BN have
particular problems evaluating the semantic and syntactic implic.ationsof the
suffix of a morphologically complex word, or is this just part of a more
extensive problem in evaluating the syntactic and semantic properties of all
types of morpheme? To investigate this possibility, we camed out Experiment 2.
Experiment 2: Stem violations
The purpose of this study was to determine whether BN's problems are confined to the processing of inflected and derived suffixes or whether they are
part of a more widespread problem with all types of morpheme. Once again,
task and our materials consisted of sentences
we used the word-tr.~ci~oring
containing inflected verbs (for additional methodological details see MarslenWilson, Brown, & Tyler, 1988; Tyler, 1985). This time, the inflection was
always contextually appropriate whereas the stem could be semantically and/
'BN's poor performance on the grammaticality task does not reflect a general inability to perform the task.
He scores well above chance on other experiments using the task for example, on the % m ematerials as
described in Experiment 2. Here his judgements were aceurate 81% of the time.
-
138
L. K . Tyler et al.
Table 3.
Experiment 2: Example stimuli
(a)
(b)
(C)
(d)
...
The crowd was very happy. John was playing the @tar and
The crowd was very happy. John was brrrying the yitu and ...
The crowd was very happy. John was drinking the guihr and ...
The crowd was very happy. John was sleeping the g n k and
...
-
or syntactically inappropriate for the context. An example set of stimuli is
given in Table.3.
We constructed 32 sentence-pairs like the example in the table. The first
sentence provided a niinimal context for the interpretation of the second
sentence. The second sentence always took the following form. A subject
noun phrase (NP) was followed by a verb which was followed by an object
NP (the word which the subject had to monitor for). These 32 normal sentence pairs, like (a) constituted the baseline condition against which the other
conditions could be evaluated. The other three conditions (b-cl) were constructed by varying the relationship between the verb and the target noun.
In (b) the pragmatic implications of the verb make the following noun pragmatically (but not linguistically) anomalous. In (c) the noun violates semantic
selection restrictions on the prior verb (Chomsky, 1965) and Ea (d) it violates
strict suhcategcrisatien restrictions on the verb.
The mean frequency (Kucera & Francis, 1967) of the verbs used in the
four conditions was 27 per million (no violation), 19 (pragmatic violation),
24 (selection restriction violation) and 26 (categorial violation). We constructed four versions of the materials. Each version contained one quarter
of the targets in each of the four conditions. Items in the four conditions were
pseudo-randomly distributed across a version with 44 filler items interspersed
between the test items. Timing pulses were placed at the onset of each target
word on the non-speech channel of the tape.
We used the word-monitoring task and the target word was always the
object noun (e.g., "guitar" in the example set). To the extent that listeners
are sensitive to these various types of linguistic and non-linguistic constraints
generated by the verb stem as they interpret an utterance, RTs to the target
noun should increase over the baseline condition (a) when they are violated.
This is indeed what we found for a group of unimpaired listeners whose
mean RTs in the four conditions are shown in Table 4. Their monitoring
latencies were significantly slowed down (compared to the undisrupted condition) by all three types of anomaly, MinF (3,155) = 12.41, p i.091.~
'The difference between each type of violation and the undisrupted condition was significant on the
Newman-Keuls statistic, using the MinF' error term. The difference between the pragmatic and semantic
violations of 26 ms was only significant on a subject's analysis.
Proc~ssingdiktinctions between stems and afaes
Table 4.
139
Mean RTs ( m ) for BN and control subjects
Undismpted
Pragmatic
violation
Semantic
violation
-- -
Controls
BN
259
487
-
303
531
Subcategory
violation
--
--
p
-
329
537
p
-
-
357
570
--p
BN's RTs, .,Ithough slower overall than the c?ntrn!s, showed essentially
the same pattern (see Table 4). His RTs for each type of anomaly were
significantly slower than for the undisrupted condition, F(3,93) = p c .OS.
Newman-Keuls post-hoc tests showed that RTs for each type of anomaly
were slower than for the undisrupted baseline condition (p c .05). These
results show, first, that BN's responses in the word-monitoring task are sensitive to various types of linguistic violations. This means that BN's insensitidity to the types of lingtlistic violations we used in the first monitoring study
did not merely reflect his inability to perform the task in the same way as
unimpaired listeners. Second, the results show that when the inflection is
consistent with the context, but the stem is contextually inappropriate in one
way or another, BN's RTs increase. This indicates that he is sensitive to the
e sthe
s semantic and svntactic information carried
contextual a ~ ~ r o ~ r i a t e nof
by stems and suggests that the problems he exhikted in t>e first study must
be due to the inflectional and derivational momhemes.
If BN has selective difficulties comprehending bound morphemes, what
aspect of the comprehension process might be the scurce of this difficulty?
To evaluate the various possibilities, we need to consiciar the range of processes involved in recognising spoken words. Listeners recz~nisespoken words
by mapping the speech input onto a representation in the mestal lexicon of
the phonological form of the word. We will assume here that this process
occurs in the way described by the "cohort model" of lexical processing
(Marsh-Wilson, 1984, 1987; Marslen-Wilson & Welsh, 1978; Tyler & Wessels, 1983). According to this model, some initial portion of the sensory input
is mapped onto all those lexical representations with which it is compatible.
These representations then become activated. As this mapping process continues, only those form representations which continue to match the sensory
input remain activated. The activation levels of non-matching representations
gradually decay. This process continues until there is only a single lexical
reprzsentation which matches the sensory input. It is at this point (the "separation point") that a word is identified. The access of form representations
is the route through which the semantic and syntactic content of a word can
L .
.
140
L,K. Tyler et al.
be accessed. In principle, a patient may have a selective problem with either
aspect of the process.
The question we now need to ask about BN is whether his problems with
bound affixes are caused by his inability either to access the form of a morpholo~icallycomplex word or to access its semantic andlor syntactic content.
In Experiments 3 and 4, we examine BN's ability to access the phonological
form of a morphologically complex word. These studies test whether he is
able to use the speech input to make contact with the form representation in
his mental lexicon of a morphologically complex word. In Experiments 5 and
6 we examine his ability to access the semantic and syntactic properties of
morphologically complex words.
Experiment 3: Sdiied words. Gating task
To determine whether BN has any difficulty with the processes involved in
mapping the sensory input onto representations of the phonological form of
a morphologically complex word, we used the gating task (Grosjean, 1980,
Tyler & Wessels, 1983; 198.5) which measures the amount of sensory input
listeners need to hear in order to identify the form of a word. Extensive
research with unimpaired listeners has shown that lexical processing is highly
efficient in the sense that listeners recognise a word at .the point at which it
diverges from all other words sharing the same initial sound sequence
(Marslen-Wilson, 1978, 1987; Tyler & Wessels, 1983, 1985).
The gating task allows us to measure this point. In this task, subjects are
presented with successively larger fragments of a word and after each fragment they either say or write down the word they think they are hearing. We
can thus determine the point in the speech stream at which BN recognises a
word and compare this with the point at which it is recognised by unimpaired
listenen.
We used a set of 18 bisyllabic test words. Twelve were morphologically
complex and 6 were simple words. All the morphologically complex words
were suffixed; half were derived and half inflected. The median frequency of
the simple, inflected and derived words respectively was 9.5,5, and 12 (Francis & Kucera, 1982). These stimuli were divided into two test blocks of 9
words, each preceded by a single practise word. The inflected words contained the suffixes [-ed], [ing], and [-es]. Each of these endings occurred once
per block. A range of derivational suffixes were used. The morphologically
simple words were a mixture of verbs and familiar, concrete nouns.
These words were pseudo-randomly ordered and then read by a female
native speaker of English. They were digitised at a sampling rate of 20 kHz
Processing distinctions between stems and afFies
141
and segmented into fragments from word onset, with each fragment increasing in duration by 50 ms. To avoid splicing artefacts at the end of each gated
segment, we smoothed the end by imposing a Hamming window on the final
5 ms of each fragment. The first fragment of each stimulus consisted of the
first 50 ms of the word, the second consisted of the first 100 ms and so on
throughout the entire word. The total number of fragments for each word
ranged from 9 to 15 (mean = 12 fragments).
The 6 control subjects (mean age 38 years) were tested in pairs in a quiet
room. They were asked to write down after each fragment the word they
thought they were hearing. BN was tested individually and the experimenter
wrote down his responses.
To assess how effectively listeners are able to map the sensory input onto
representations of phonological form, we measure the point at which each
subject correctly identifies the word without subsequently changing his or her
mind. This is called the "isolation point" (IP; Grosjean, 1980,Tyler & Wessels, 1983,1985;Marslen-Wilson, 1984). In a number of studies, it has been
shown that the IP correlates quite highly with the "separation point" as defined by the cohort model (Msrslen-Wilson, 1987; Tyler, 1984). In studies
with unimpaired listeners, we also estimate the "recognition point", which is
the point at which subjects correctly identify the word with some criteria1
degree of confidence. Since it is often not possible to obtain confidence ratings from aphasic patients, we only calculated the isolation points in this
study. For each morphologically complex word, we measured the isolation
point for the full form and for the stem.
BN identified the total set of words at approximately the same point as
the control subjects. An ANOVA calculated on the IPs for BN and the
control group showed no significant differences, F(1,12) = 1.118, p = .0311.
His mean IP for the full form of the simple and complex words combined
was 322 ms, whereas the mean IP of the control group for the same words
was 340 ms. Since the mean duration of the set of words used in the study
was 600 ms, this means that both the control subjects and BN were correctly
identifying a word after they had heard about half of it.
A similar pattern was found for the derived and inflected words. BN's
mean IP for the derived words was 380 ms, compared with 360 ms for the
control group, and his PP for the inflected words was 350 ms, which was not
significantly different from the control group's 320 ms. Similarly, he recognised the stem of both derived and inflected words at the same point as the
control subjects (230 ms for controls vs. 255 ms for BN). There was one
difference between BN and the control group. BN failed to identify two
inflected words (fixes, sorted) by the end of the word. He did, however,
correctly identify the stems of these words at the point where the control
142
L.K. Tyler et al.
subjects identified them, but failed to put the correct inflection on the stem.
Instead, he used the inflection [kg].
These results from the gating task suggest that, for the most part, BN
recognises both morphologicdiy simple and complex words in the same way
as unimpaired listeners. That is, he maps the sensory input onto representations of lexical form and recognises a word at the same point at which it is
recognised by the control group. Thus, he appears to be able to access the
phonological form of a morphologically complex word in much the same way
as unimpaired listeners.
Experiment 4: Suffixed WO&
Auditory lexical decision task
The results of the gating task told us about BN's general ability to access the
form of morphologically complex words. In this fourth experiment, we
examined his ability to correctly identify the same inflected and derived test
words we had used in Experiment 1, and to discriminate these words from
non-words. In that experiment, we found that BN was insensitive to the
contextual appropriateness of a suffixed word and also to its legal morphologicai structure. The question we ask here is whether this is because he is
unable to access the phonological form of those particular words. We do this
by using the auditory lexical decision task. This enables us to determine
whether BN can distinguish the suffixed real words from the morphologically
complex non-words used in Experiment 1.
The experimental stimuli consisted of the same derived and inflected lest
words used in Experiment 1. There were 45 suffixed real words, which were
a mixture of derived (e.g., wasteful) and inflected (e.g., causes) words, and
20 morphologically simple real wards (e.g., shadow). Each real word had a
corresponding non-word. WC created morphologically complex non-words
by substituting each word suffix with another suffix so that the resulting
combination produced a non-word. For example, by changing the suffix on
the real word ~vasreful,we created the non-word wastely. We turned morphologically simple words into non-words by changing the last syllable. So,
for example, shadow became the non-word shadit. We included 140 filler
items - half of which were words and half non-words. The real word fillers
consisted of 25 conplex words (both prefixed and suffixed words) and 45
simple words. Thus, the number of simple and complex words were fairly
evenly balanced with the combination of test a d filler items. The non-word
fillers included simple words which had undergone phonetic changes ic varying positions in the word, and prefixed non-words.
SO that subjects would only hear one member of a wordlnon-word pair at
Processing distinctions between stems and afFies
143
a single testing session, we created two versions of the materials. Each version
contained half the test materials - with an even number of real words and
non-words - and all the filler items. Only one member of a wordlnon-word
pair occurred in each version. Each version was recorded for auditory presentation to subjects.
BN and a group of 6 control subjects (mean age 37 years) were presented
with the list of stimuli over headphones. BN was asked to say whether each
stimulus was a real word or a non-word, and his responses were recorded.
The control subjects wrote down their responses on a score sheet.
The control subjects were very accurate and made very few errors. They
correctly accepted all the morphologically simple real words and rejected tne
simple non-words. They made more errors on the suffixed words, failing to
accept 4.76% of the derived real words and failing to reject 2% of the inflected non-words. Although BN made more errors than the controls, none
of the differences were significant and his pattern of performance was essentially the same as the control grcup's. He was very accurate with simple
words, only failing to accept one simple real word. Like the control subjects,
he made errors with morpho1ogia:ly complex words. He failed to accept 6
(13%) of the morphologically complex real words and failed to reject 3 (7%)
of the complex non-words. However, the difference in the number of errors
between the two types of word was not significant (simple vs. complex real
words: 2 = 1.45, p = .0735; non-words z = 1.418,~= .0778). BN also made
more errors on inflected (17%) than derived words (9.5%), but again this
difference was not significant (z = 13.7031, p = .242).
Overall, BN was 90% correct in his ability to distinguish suffixed real
words from non-words comprised of two real-word morphemes. On the
whole, then, he was sensitive to the lexical status of suffixed words, suggesting
that he does not have a serious problem accessing the form of a morphologically complex word. This suggests that his problems with suffixed words in
Experiment 1 were not due to his inability to access the form of the morphologically complex words we used in the study.
The results of Experiments 3 and 4 show that BN can efficiently map the
sensory input onto the mental representation of the phonological form of a
suffixed word, and that he can accurately discriminate real suffixed words
from non-words. Taken altogether, then, the resi:!tq suggest that he does not
have any difficulty in accurately identifying the phonological form of a suffixed word.
If BN's insensitivity to the contextual appropriateness of morphological
affixes is not due to problems in mapping the sensory input onto form-based
lexical representations, it must be due to his inability to access the semantic
and syntactic properties of bound morphemes. To test this hypothesis, we
144
L.K. Tyler et al.
designed two studies with inflected words in which we tried to separate those
aspects of inflections which affect the grammatical structure of utterances
(Experiment 5) and those which affect the semantic interpretation of an utterance (Experiment 6).
Experiment 5: Inflected words and their syntactic implications
This study examined the role of inflected words as they relate to the syntactic
structure of an utterance. It enables us to determine whether BN has problems in processing inflections when they serve a purely syntactic role in an
utterance - in this case, by constraining the structural organization of an
utterance. Test stimuli consisted of sentences with the structure: NP + AUX
+ [V+istlection] + NP. An example set of stimuli is given in Table 5.
The second noun was the target word which the subject had to monitor
for (we used the word-monitoring task as in Experiments 1 and 2). The
nature of the inflection on the verb determined whether the verb was transitive or intransitive and this, in turn, set up a structural preference for either
an NP or PP (prepositional phrase) to follow the verb. When the suffix is
[-in& the verb is transitive and an NP is the preferred continuation. When
the suffix is [-ed] the sentence is in the passive voice, the verb is intransitive
and a PP is the preferred continuation. All past tense inflections were regular
and syllabic, and both inflected forms were appropriate for the prior context.
It is the form-class of the target word following the inflected verb which
creates a syntactically legal or illegal continuation.
A series of pre-tests established the syntactic appropriateness or inappropriateness of the target noun.3 The question is whether BN can access the
syntactic properties of the inflected verb and integrate them into the sentence
representation. If he can, then RTs to targets following transitive verbs
should be faster than those following intransitive verbs.
The test sentence was either heard in isolation or it was preceded by a
context sentence. We introduced this manipulation in order to see whether
-bne pre-test "etermined whether past tense verbs used in the inconsistent condition would be given a
valid interpretation i f the verb was parsed as an adjective (e.g., "They were baked potatoes ...").The possibility of subjects interpreting the verb as an adjective had to be excluded otherwise items in the inconsistent
condition would not necessarily be interpreted by the listener as being incorrect. A second pre-test established
the strength o f biases in the No-context condition. The number and animacy of the first N t o f the test
sentence. together with the semantic features o f the verb itself, may combine to provide a bias towards either
a progressive or passive reading. or they maye: neutral and provide no specific bias. Items were categorised
into one of the 3 bias categories according to subjects' responses. This did not interan with the effect of the
consistency of the target (MinF' c l).
Processing distinctions berween stems and affires
Table 5.
145
Experiment 5: Example stimuli
-
-.
~
.
~
-
~
~
~~
Context:
Eric spent horn sitting by his easel.
(a)
(b)
Appropridte target:
He was painting boat6 down by the riverside.
Inappropriate target:
He was pointed boab down by the riverside.
-.
~ a b l e6.
.-
--
p
Mean RT in ( m ~for
) the control .subjects and BN
Context
Controls
BN
-.
NO-context
-
-.
.
.
Correct
Incorrect
Correct
Incorrect
228
374
282
255
378
382
322
387
-
p
~
-
the presence or absence of a prior context affects BN's ability to use the
syntactic properties of the suffix.
For the 36 test items we used in the study, the median frequency of the
inflected verbs in the consistent and inconsistent conditions was 3 and 8.5,
respectively. The median frequency of the target nouns was 27. We produced
four versions of the 36 test items, such that each test item appeared in each
version in only one of the four conditions. In each version, the test items
were interspersed with 56 filler items, designed to counteract their regularities. The sequence of test and filler items was constant across the four
conditions. They were prececr~dby 10 practice items.
The items were recorded by 2 female native speaker of English onto one
channel of a stereo tape. Timing pulses were placed on the non-speech channel of the tape, synchronous with the onset of the target word.
The 24 young controls (ranging in age from 18 to 35 years) each heard gnly
one version of the materials. BN was tested on all four versions, with one
month separating each testing session.
For the control subjects, whose mean RTs are displayed in Table 6, we
found that RTs were faster when target words followed a transitive verb (247
ms) than an intransitive (282 ms) verb, MinF(1,41) = 25, p < .001. This
suggests that the inflectional suffix functions to immediately constrain the
syntactic structure of the utterance and this determines the syntactic appro-
146
L.K. Tylerefal.
Figure 1. Mean differences between consistent and inconsistent RTs for the contat
and no contexf conditions in Experiment 5.
Context
El ~ocontext
priateness of the following noun. When it is inappropriate, RTs are longer
than when it is appropriate. Figure 1, which presents the differences between
the consistent and inconsistent conditions for the context and no-context
conditions separately, shows that this effect was not modulated by the presence or absence of a discourse context (F < 1). RTs were faster to targets
following transitive verbs whether or not there was a prior context sentence.
The only effect which the discourse context had was to generally make it
easier to identify the target word, MinF(1,27) = 4.57, p < .OS.
BN's results are different from those of the control group. Most importantly, his latencies to respond to the target word are unaffected by the
structural constraints generated by the transitivity of the verb (see Figure 1).
When the verb is transitive and the target word is structurally appropriate his
mean RT is 378 ms compared with 382 ms when the target noun is structurally
inappropriate. An ANOVA comparing RTs in the appropriate and inappropriate conditions (collapsed across context) showed that these RTs were not
significantly different from each other, F(1,19) = 0.480, p > .OS. Moreover,
the differencebetween these two conditions was outside the confidence limits
for t b control group (p > .OS). BN also showed no effect of the prior
context, F(1,19) = 0.793, p > .OS. RTs were not significantly different
whether the sentence was heard in isolation (385 ms) or preceded by a context
sentence (376 ms) and there was no interaction between context and the
appropriateness of the suffix.
Processing distinctions between stems and aflxes
147
These results show that BN is insensitive to the structural implications of
inflectional suffixes - at least of the type we used in this study. The next
question we asked was whether BN is also insensitive to inflectional suffixes
when they play a semantic, rather than syntactic, role in an utterance.
Experiment 6: Inflected words and their anapboric implications
In English, the inflectional morphology does not only have a grammatical
function. Because it marks tense and number. it also serves an anaphoric or
deictic role. That is, inflectional morphemes can function to maintain time
and reference within a d i m m e . For example, the present tense morpheme
can either maintain the tense of the discourse or can signal a change of time.
In this way, inflectional morphemes serve a semanticJpragmatic function in
sentences. By examining BN's ability to process tense markers, we can determine whether he can evaluate the semantic implications of the inflectional
morphology.
The test materials (see Table 7 for an example) consisted of a context
sentence followed by a continuation sentence. The context sentence was coilstructed so that it set up the present tense. The continuation sentence contained a verb which was either in the present or past tense. When the verb
was in the present tense, verb tense and context tense were consistent. But
when the verb was in the past tense, then the verb tense was inconsistent
with the tense set up by the context sentence. A noun, functioning as a target
word, immediately followed the tensed verb. If a listener is sensitive to inflectional morphemes marking tense, we expected monitoring latencies to be
longer when there is a mismatch between context and verb tense.
Two pre-tests ensured (a) that the test verb in its present tense form was
appropriate for the tense established by the prior context whereas the past
tense form was not, and (b) that the inappropriately inflected verbs (the past
tense forms) were considered by subjects to be inappropriate.
There were 20 test items. The median frequency of the targets in these
Table 7. Experiment 6: Example stimuli
)(a)
I(b)
~
Consistent tense:
Alison isn't frightened of many things. These days she only hares bees and wasps if they
crawl into her food.
Inconsistent tense:
Alison ishit frigintened of many things. These days she only hared bees and wasp if they
crawl into her food.
p
p
-
~-~
~
~~
~
~~
--
~
148
L.K. Tyleretal.
items was 18. Each test item appeared in two conditions: (a) where the
context and verb tense were consistent; and (b) where they were inconsistent.
Two versions of the materials were constructed so that each subject would
hear each test item in only one condition. In each version the test items were
pseudo-randomly interspersed with 60 filler sentences.
The test items were counterbalanced for the syllabicity of the inflections,
in case BN had special problems perceiving non-syllabic inflections. Half the
test verbs had syllabic present tense forms (consistent items) and their corresponding past tense forms (inconsistent items) were non-syllabic. For the
other 10 verbs, the present tense forms were non-syllabic and the past tense
forms were syllabic.
Monitoring RTs for the control subjects (see Table 8) were significantly
slower when the verb tense was inconsistent with the context tense, but only
when the inflection was syllabic (213 vs. 265 ms). When the inflection was
not a full syllable, then RTs were not affected by the consistency of verb and
context tense (223 vs. 234 ms ). On an ANOVA, the syllabicity by consistency
interaction was significant, F(1,39) = 12.87, p < .001. The differences between the consistent and inconsistent conditions are shown in Figure 2.
The lack of a consistency effect for the non-syllabic inflections may be due
to the specificity of the bottom-up input. A non-syllabic inflecti~nis a more
impoverished acoustic-phonetic stimulus than an inflection which is a full
syllable, and the context may compensate for this minimal stimulus. There is
amole evidence that listeners modulate their use of various kinds of information as the situation demands it. For example, less acoustic-phonetic information needs to be ~rovidedbv a s~eakerfor the correct identification of a word
when an approphately consbai;ng context is available (e.g., Grosjean, 1980;
Marslen-Wilson & Tyler, 1980; Miller, Heise, & Lichten, 1951). Such data
suggest that the normal language-processing system is organized to allow the
cooperative integration of different types of processing inforniarion with respect to the primary goal of interpreting an utterance within its discourse
context. The fact that we do not see a consistency effect for non-syllabic
Table 8. Mean RT in (ms) for BN and the control subjects
~
~..
~
Non-syllabic
Syllabic
~
~.-
-..-~
Controls
BN
~
~
Consistent
~
213
358
~
-
-.-..
~~~
Inconsistent
Consistent
Inconsistent
. . .-
-
265
282
223
375
. .,
~
~
~
234
370
-~
-~
~-
~
~
p
~
~
-
Processing dktinctions benveen stems and affixes
149
Figure 2. Mean differences between the consistent and inconsistent conditions for the
syllabic and non-syllabic items in Experiment 6.
Syllabic
Moneyllabic
'001
-100
'
Controls
BN
inflections may be another example of this general process. Supporting this
hypothesis is the fact that RTs for both the consistent (223 ms) and inconsistent (234 ms) non-syllabic inflections are more similar to RTs for the consistent syllabic inflections (213 ms) than to RTs for the inconsistent sy1lab:c
inflections (265 ms). This suggests that the tense of both the consistent and
inconsistent non-syllabic inflections is being interpreted as consistent with the
tense of the context.
BN also shows no effect of the consistency of the non-syllabic inflections
(375 vs. 370 ms) but, unlike the controls, his latencies are not slower when
context and verb tense are inconsistent for the syllabic inflections (see Table
8 and Figure 2). In fact, his RTs are faster when the syllabic inflection is
inconsistent with the context (282 ms) than when it is consistent (358 ms)
with the context (t = 1.72, p = .OS). This difference between the two conditions was outside the confidence limits for the control group. For non-syllabic
inflections, the difference beiween the two conditions was not significant
(t = 0.13, p > .OS). These results suggest that BN is unable to integrate the
anaphoric properties of the inflectional suffix (even when it is a full syllable)
into the representation of the senteace context.
150
L.K. Tyler et al.
Conclusions
The results of the six experiments described here show that BN has problems
with the processing of inflectional and derivational suffixes and, moreover,
they pinpoint the specific source of the problem. Experiments 3 and 4 established that BN's problems do not lie in his ability to access the phonological
form of a morphologically complex word. In an auditory lexical decision task
we found that he could accurately distinguish suffixed words from non-words,
and in a gating task he recognised derived and inflected words after hearing
the same amount of sensory input as the control subjects. The data from the
gating study show that he is able to map the sensory input onto the appropriate representation of the phonological form of a morphologically complex
word and that his processing of the speech input is, like unimpairec' listeners,
highly efficient.
Experiments 1, S and 6 showed that BN's ~roblemslie in his inability to
integ;ate the semantic and syntactic
of morphologica1:y complex
words into the higher-level sentential representation. Whether a momholoni -ally complex word generates inappropriate structural constraints ( ~ x ~ e i ~ i i ~ S)
n t or violates the tense of the discourse (Experiment 6) BN, unlike
nnrmal controls, is insensitive to both types of violation. The results of Experiment 2 showed that this insensitivity to both the syntactic and semantic
appropriateness of a morphologically complex word is confined to inflectional
and derivational suffixes themselves. In this study, BN demonstrated that he
had no problems in accessing the semantic and syntactic properties of stems
and integrating them into the higher-level sentential representation. When
the inflection was contextually appropriate but the relatibnship between the
stem and the context was inappropriate, either on semantic or syntactic
grounds, BN was as sensitive to these violations as unimpaired listeners.
Hcwever, when the reverse situation held and the stem was contextually
appropriate but the suffix was contextually inappropriate, BN was insensitive
to the violations. Thus, it appears that BN has specific problems in integrating
the syntactic and semantic aspects of the inflectional and derivational morphology into the contextual repre~entation.~
What conclusions follow from these results? First, there is 30 suggestion
in these data that the underlying cause of BN's language comprehension
disorder is due to a selective impairment in the representation of syntactic
? h e way that BN processes morphologically complex words does not make clear predictions about bow
he should process freestanding grammatical markers. If he treats them like stems (and certainly some types
of free-standing grammatical morphemes could be considered to be more stem-like than affix-like), he should
pcrform normally: if he treats them like aftixes, he should have problems.
Processing disrinctions between srems and affixes
151
knowledge associated with bound morphemes. For this to have been the
case, he should have shown selective difficulties with those bound morphemes
which are thought to primarily play a syntactic role in utterances (inflectional
morphemes), and with the syntactic, as opposed to the semantic, properties
of inflectional morphemes. Instead, he showed similar degrees of impairment
for both the derivational and inflectional morphology, and he showed no
sensitivity to either the syntactic or the semantic properties of inflectional
morphemes.
In his across-the-board problem with both types of suffixed words, BN is
unlike some other ;-~tientsreported in the literature, who show a selective
deficit fcr the inflectional morphology (Miceii & Caramazza, 1987; Tyler &
Cobb, 1987) and appear to comprehend derived words normally. This is
particularly interesting given that his spontaneous speech is so similar to that
of the patient reported in Tyler and Cobb (1987) who has difficulty comprehending only inflected forms. It adds support to the claim that patients
typically labelled as "agrammatic" ' 1 their speech production may have different underlying comprehension deficts (Martin et al., 1989; Goodglass &
Menn, I985), and calls into question theories which describe the disorder as
a central syntactic deficit.
BN appears to analyse both derived and inflected words in ihe same way
-by recognising the stem and not processing the suffix. This is not to say that
once he recognises a stem he does not extract any information from the rest
of the word. Experiments 3 and 4 show that the acoustic-phonetic input
corresponding to the entire full-form of a morphologically complex word is
mapped onto its form-based lexical representation. So, the entire phonological form of the word is analysed at the lexical level. What seenls to be
happening is that only the syntactic and semantic content of the stem is
accessed and integrated with the context. Tile semantic and syntactic implications of the suffix are never evaluated.
This implies that the content of stems and affixes can be evaluated against
the context independently of each other. This, in turn, suggests that stems
and suffixes must be separately represented at some level in the mental lexicon (cf. Tyler & Marslen-Wilson, 1986). Moreover, since BN shows the
same pattern of results for both derived and inflected words, we conclude
that this may hold for both types of morphologically complex words. However, we can only make this c!aim with any certainty for the particular type
of suffixed words we used in our experiments. These were words in which
the relationship between the stem and the suffix was both phonoiogically and
semantically transparent. They were phonologically transparent in that the
suffix did not cause major phonological changes to the stem, and they were
semantically transparent in that the meaning of the full-form was readily
152
L.K. Tyler er al.
recoverable from the meaning of the stem. This was true for both the derived
and the inflected words (e.g., completedlcomplet(e.g., enjoyab~elenjoyment)
ing). BN's data suggest that suffixed words with these properties may be
represented in the mental lexicon as stems plus their associated affixes whether or not they are derivecl or inflected. If this is the case, then inflected
and derived words may not 11tct:ssarily have different types of representation.
The question which remains open is whether morphologically complex
words which are semantically opaque (e.g.. department) are represented in
the same way as those which sre semantically transparent -.that is, in terms
of a stem and its associated affixes. (This only applies to derived words, since
inflected words are always semantically transparent.) If they are not, then
the way in which a complex word is represented in the mental lexicon may
depend more upon whether its meaning is readily recoverable from its component parts than upon whether it is derived or inflected.
References
Anderson. S. (1982). Where's morphology? Linguinic Enquiry. 13.571-612.
Benton. A.L.. & Joynt. R.J. (1959). Reaction time in unilateral ierebral disease. Confiiu fleurologica, 19.
247-256.
Berndt. R.. & Caramaua. A. (1980). A redefinition of the syndrome of Bmca's aphasia: Implications for a
neuropsychologiwl model of language. Applied Psycholinguistics. 1.225-278.
Bishop. D. (1982). TROG: Test for the Reception of Grammar. Abingdon. U.K.: Thomas Leach (for the
Medical Research Council).
Butterworth. B. (1983). Lexical representation. In B. Butterworth (Ed.;. Language Production (Vol. 2).
London: Academic Press.
Chomsky. N. (1965). Aspects of the theory of syntax. Cambridge. MA: MIT Press.
Cooper. W.E.. & Zurif. E. (1983). Aphasia: Information processing in language production and reception.
In B. Butterworth (Ed.). Language production (Vol. 2). London: Academic F'ress.
J e Renzi. E.. & Faglioni. F. (1978). Normative data and screening power of a shortened version of the Token
Test. Cnrte.~.14. 41-49,
Devillien. J.G. (1978). Fourteen grammatical morphemes in acquisition and aphasia. In A. Caramazza &
E. Zurif (Eds.). Language acquisition and language breakdown: Parallels and divergences. Baltimore:
Johns Hopkins Clnivenity Press.
Eling, P. (1986). Recognition of derivatims in Broca's aphasia. Brain and Language, 28, 346-356.
Francis, W.. & Kucera. H. (1982). Frequency Analysis of English Usage: Lexicon and Grammar. Boston:
Houghton MiMin.
Garrett. M. (1980). Levels of processing in sentence production. In B. Butterworth (Ed.), Languageproduction (Vol. 1). London: Academic Press.
Gwdenough. C.. Zurif. E.. & Weintraub. S. (1977). Aphasia' attention to grammatical morphemes. Language and Speech. 20. 11-19,
Goodglass. H.. & Berko. 3. (1%0). Agrammatism and inflectional morphology in English. Journal of Speech
and Hearing Research. 3,257-267.
Goodglass. H.. Gleason, J.. Ackerman. N.. & Hyde, M. (1972). Some linguistic structures in the speech of
a Broca's aphasic. Conex, 8, 191-212.
Processing distinctions between stems and affixes
153
Goodglass, H., & Kaplan, E. (1972). The ASS~~Y?I~FZ?
of Aphasia and Related Disorders. Philadelphia: Lea &
Febiger.
Goodglass, H., & Menn, L. (1985). Is agrammatism a unitary phenomenon? In M.L. Kean (Ed.), Agrammatism. New York: Academic Press.
Grodzinsky, J. (1984). The syntactic characterisation of agrammatism. Cognition, E&99-120.
Grosjean, F. (1980). Spoken word recognition processes and the gating paradigm. Perception and
Psycnophysics, 28,267-283.
Grossman. M., Carey, S., Zurif, E., & Diller, L. (1986). Proper and common nouns: %rr, class judgements
in Broca’s aphasia. Brain and Language, 28, 114-125.
Kucera, H., & Francis. W. (1967). Computationalanalysisof present-day American English. Providence, RI:
Brown University Press.
Linebarger, M., Schwartz, M., & Saffran, F. (1983). Grammatical judgements in so-called agrammatic
aphasics. Cognition, 13,36!-392.
Lukatela, K., Grain, S., & Shankweiler, D. (1988). Sensitivity to inflectional morpllology in agrammatism:
Investigation of a highly inflected language. Brain and Language, 33; l-15.
Marslen-Wilson, W.D. (1984). Function and process in spoken word recognition. In H. Bouma and H.
Bouhuis (Eds.), A:tcwion and Performance X: Contrc! gf Language Processes. Hillsdale, NJ: Erlbaum.
Marslen-Wilson, W.D. (1987). Fun&onal parallelism in spoken word recognition. Cbgnition, 25, 71-102.
Marslen-Wilson, W.D., Brown, C., LyrTj!er, L.K. (1988). Lexical representations in spoken language comprehension. Language and Cognitive Processes, 3. l-17.
Marslen-Wilson, W.D., & Tyler, L.K (1980). The temporal structure of spoken language understanding.
Cognition, 8, l-71.
Marslen-Wilson, W.D., & Welsh, A. (1978). Processing interactions and lexical access (during word recognition
in continuous speech. Cognitive Psychology, 10, 29-63.
Martin, R., Blossom-Stach, C., & Feher, E. (1989). Syntactic loss versus processing deficit: An assessment
of two theories of agrammatism and syntactic comprehension deficits. Cognition, 32, 157-191.
Miceli, G., & Caramazza, A. (1987). Dissociation of inflectional ar:d derivqtional morphology. Dissociation
of inflectional and derivational morphology. Reports of the Cognitive Neuropsychology Laboratory,
Johns Hopkins University.
Miller, G., Heise, G,, & Lichten, W. (1951). The intelligibility of speech 2s a function of the context of the
test materials. Journal of Experimental Psychology, 41, 329-336.
Patterson, K. (1979). What is right with deep dyslexic patients? Brain and Larguage, 8, 111-129.
Stemberger, J., & MacWhinney, B. (1986). Frequency and the lexical storage of regularly inflected forms.
Memory and Cognition, 14, 17-26.
Tyler, L.K. (1984). The structure of the initial cohort: Evidence from gating. Perception arzd Psychophysics,
36,417-427.
Tyler, L.K. (1985). Real-time comprehension processes in agrammatism: A case study. Brain and Language.
26, 259-275.
Tyler, L.K. & Cobb, H. (1987). Processing boi:nd grammatical morphemes in cantext: The case of an aphasic
patient. Language and Cognitive Processes, 2, 245-262.
Tyler, L.K., & Marslen-Wilson, W.D. (1986). The effects of context on the recognition of polymorphemic
words. Journal of Memory and Language, 25, 741-752.
Tyler, L.K., & Wessels, J. (1983). Quantivng contextual contributions to word recognition processes. percep
tion and Psychophysics, 34,405-420.
Tyler, L.K., & Wessels, J. (1985). Is gating an on-line task? Evidence from naming latency data. Pe=ption
and Psychophysics, 38, 217-222.