Auditory Comprehension Problems in Adult Aphasic
Individuals
Cynthia M. Shewan
Whether an aphasic patient understands what is said
appears to be influenced by many factors in addition to
the message itself, among them: how the material is presented, what the situational context is, the nature of the
response required, the individual's cognitive functioning,
his/her motivation, and the location and extent of the
cerebral lesion_ Of course, the individual engaged in the
comprehension task is also important. The nature of
auditory comprehension problems in adult aphasic individuals is indeed complex, but we are making headway_
To paraphrase Shakespeare, To understand or not to
understand is a complex question.
Researchers now generally agree that all aphasic
patients demonstrate auditory comprehension problems_
Of less consensus is whether all comprehension problems are similar in type.
Whenever we communicate with an aphasic patient,
during testing or in conversation, some of the time we talk
and the patient listens. These interactions require that the
aphasic person understand our linguistic messages.
Whether that understanding takes place is influenced by
many factors operating in the situation, including auditory
perception, auditory comprehension, and factors which
influence auditory comprehension.
Presumably, the ultimate goal of processing messages is to comprehend them, that is, to assign appropriate meaning to them. Take the message "Gotcha".
What does it mean? Interpretation depends upon linguistic
aspects, context, and extralinguistic variables. Said by a
parent to a young child, "Gotcha" represents "I've got
you, you're not going to fall". Used in the context of
playing a game of tag, or changed slightly to "Caughtcha",
it means "Tag, you're it". Said by an adult during conversation, it might mean "I understand what you said", or, in
another context with a different intonation pattern, it
might mean "You fell into the trap I set for you". Uttered
during a game of cowboys and rustlers, "Gotcha" represents "Bang, bang, you're dead". The point of this example
is to illustrate that whether a person understands or fails
to understand depends on many dimensions of the communication situation as well as the processing of the
Cynthia M. Shewan, Ph.D.
University of Western Ontario
Address Correspondence To:
Cynthia M. Shewan, PhD.
Department of Communicative Disorders
University of Western Ontario
Elborn College
London, Ontario N6G IHl
auditory and linguistic message components (Figure 1).
This applies to aphasic patients functioning in everyday
situations and in the clinical setting.
PSYCHOLOGICAL
VARIABLES
PRESENTATION
VARIABLES
Figure 1. Dimensions influencing auditory comprehension of a linguistic message.(reprinted with
permission).
Processing Auditory Stimuli:
Perceptual Data
Auditory perceptual deficits do not appear to be the
major contributing factors to aphasic patients' inability to
understand auditory messages. The auditory perceptual
problems may involve discrimination, recognition, and/or
temporal ordering, using verbal or nonverbal material,
and may be found among several aphasic types. However, the disociation betweeen perceptual problems and
comprehension problems in many aphasic patients precludes using perceptual problems as the explanatory
cause for comprehension deficits. Recognizing a "towel
rack" as a "motorcycle", as one of our aphasic clients did,
probably represented a semantic confusion that did not
involve a failure of perceptual processing.
Processing Auditory Language:
Understanding the Linguistic Input
Comprehension of spoken language requires individual processing of the linguistic components· phonology, semantics, and syntax - as well as interactive processing among them.
Phonology
Comprehension requires the ability to perceive
speech and to identify phonemes with some accuracy,
but the suprasegmental aspects of phonology are also
important. Perception of stress as a phonemic cue
appears to be maintained in aphasic adults (Blumstein &
Goodglass, 1972), allowing them for example to distinguish "record" from "record". Stress is an important
factor in aphasic patients' performance on receptive lan-
Human Communication Canada/Communication Humaine Canada, Vol. 9, No. 5, 1985
151
guage tasks and exaggerating stress can assist comprehension (Kellar, 1978; Pashek & Brookshire, 1980).
Although the cues provided by intonation contours
may be redundant for normal adults, they appear to be
necessary for aphasic patients with severe comprehension problems (Boiler & Green, 1972; Green & Boiler,
1974). When presented with questions, statements, or
commands, aphasics made few correct responses. However, their many appropriate responses, which matched
the type of grammatical structure, suggested that they
were obtaining relevant information from the intonation
contour of the message.
Lexical Processing
Part of the aphasic patient's difficulties in understanding language stems from impairment in the lexicon,
which Schuell, Jenkins and Jimenez·Pabon (1964) described as a "reduced availability of vocabulary". Frequency of occurrence of lexical items and their semantic
category membership are known to influence comprehension (Goodglass et al., 1966; Shewan & Canter, 1971).
The research data for the effects of grammatical form
class on comprehension, however, have been less consistent, and more controlled study is needed before firm
conclusions are drawn (Goodglass, G leason & Hyde, 1970;
Parisi & Pizzamiglio, 1970; Shewan, 1976; Smith, 1974).
Aphasics' performance on auditory identification
tasks may also represent an impairment in semantic
representation or semantic knowledge. Aphasic patients
have been shown to have difficulty grouping lexical items
on the basis of semantic features (Zurif et al., 1974).
Furthermore, their semantic category boundaries were
found to be different from those of normal adults in terms
of scope and hierarchical organization (L'hermitte,
Derouesne, & Lecours, 1971; Derouesne & Lacours,
1972). Therefore, lexical impairment may involve not only
a less accessible vocabulary but also disturbed semantic
representation.
Semantic and Syntactic Processing
Work in semantic and syntactic processing has indicated that, as the grammatical complexity of a sentence
increases, there is a corresponding decrease in compre·
hension accuracy. A typical difficulty hierarchy is shown
in Table 1. Not only is the sentence type itself an impor·
tant contributor to comprehension, but there are also
differences within types. Reversible sentences are more
difficult than nonreversible ones (Lasky, Weidner, &
Johnson, 1976; Caramazza & Zurif, 1978). Sentences
which follow an order of mention strategy are easier to
understand than those which do not (Ansell & Flowers,
1980). Whether sentences are true or false also influences
comprehension (Brookshire & Nicholas, 1980; Just,
Davis, & Carpenter, 1977). Increasing the length of sentences mayor may not increase comprehension difficulties, depending upon other variables (Shewan, 1979).
Comprehension of a series of sentences, such as a
paragraph or text, is often more impaired than isolated
sentence comprehension in adult aphasic patients. This
152
increase in task difficulty generally stems from the greater
amount of material to process and the necessity to relate
the material together.
Although most research has investigated aspects of
denotative meaning, impairment of connotative aspects
parallels that for denotative meaning (Gardner & Denes,
1973). Comprehension of metaphorical meaning in both
single sentences and paragraphs, by contrast, is maintained in aphasic patients (Stachowiak et al., 1977;
Winner & Gardner, 1977).
In summary, it appears that a variety of phonological,
semantic, and syntactic variables influence aphasic
patients' auditory comprehension.
Table 1
Hierarchy of Difficulty for Sentence Types from Easy to
Difficult
EASY
SENTENCE TYPE
Simple Active Affirmative Declarative
e.g., The dog is chasing the cat.
NEGATIVE
e.g., The dog is not chasing the cat.
Passive
A. Nonreversible
e.g., The ball is being caught by the dog.
B. Reversible
e.g., The cat is being caught by the dog.
Nega tiue· Passive
e.g., The cat is not being chased by the dog.
Cent er· Embedded
A. Nonreversible
e.g., The cat that the dog is chasing
is meowing.
DIFFICULT B. Reversible
e.g., The cat that the dog is chasing
is black.
C. Improbable
e.g., The boy that the dog is patting
is fat.
Other Dimensions Influencing Auditory
Comprehension
Other dimensions to consider are context, manner
of presentation, form of response, psychology, and extralinguistic. Both linguistic and situational context variables
can influence comprehension. A supportive linguistic
context usually aids comprehension (Gardner, Albert, &
Weintraub, 1975; Wailer & Darley, 1978) by creating a set
for the aphasic person (e.g., structuring all questions in a
"yes-no" format rather than random presentation of several varieties), by reducing the number of likely alternatives, or by providing cues about what is to follow.
Although linguistic context is generally used by speech-
Human Communication Canada/Communication Humaine Canada, Vo!. 9, No. 5. 1985
language pathologists and family members to aid comprehension, context in the form of competing messages
or indirectly worded messages can reduce comprehension (Green & Boiler, 1974).
Situational context may also positively influence
comprehension performance by adding redundancy to
the linguistic message. This facilitates linguistic processfng by biasing the subject toward using one strategy
rather than another or by limiting the number of possibilities in a situation. For example, the patient does not need
to comprehend the entire question "Would you like
orange juice?" since this is more likely to occur than
"Would you like orange socks?" in the context of a breakfast situation.
Research has also shown that aphasic individuals
may perform differently depending on the situation in
which they are observed. The fact that aphasic patients
are likely to perform better in the clinical situation with a
speech-language pathologist that in other environments
may explain discrepant reports by various health professionals about aphasics' auditory comprehension (Egolf &
Chester, 1977; Helmick, Watamori, & Palmer, 1976).
Moreover, a speaker's intended meaning does not always
correspond to the literal meaning of the words used.
Aphasic individuals' difficulty comprehending indirect
requests, such as "Must you tap that pencil?", demonstrates the importance of context in determining an
appropriate interpretation.
How messages are presented to the aphasic patient
can influence understanding. Timing aspects of verbal
messages are important to aphasic patients' comprehen·
sion. Expanding the speech signal by inserting pauses has
a positive effect on comprehension, either on the accuracy or on the speed of response (Liles & Brookshire,
1975; Sheehan, Aseltine, & Edwards, 1973). Longer
pauses appear to be more facilitory. Aphasic individuals
may use different strategies during pause time (Salvatore,
1975). Expanding both speech and pause intervals has
not generally facilitated comprehension, although com·
pressing the signal in this way is detrimental to it (Bergman et al., 1977). Supplementing the primary auditory
input modality with visual information (gesture, written
language) can assist comprehension (Gardiner & Brookshire, 1972; Yorkston, Marshall, & Butler, 1977; Yorkston, Beukelman, & Waugh, 1979).
Presentation aspects, such as repetition of the message, frequently improve aphasic patients' performance
(Brookshire, 1978; Schuell, Jenkins, & Jimenez-Pabon,
1964). Live voice presentation of auditory material is
superior to tape recorded presentation (Boiler et aI.,
1979). The sequence of events presented may also be
important because presentation of difficult commands,
interspersed among easy ones, has been shown to interfere with aphasics' performance on commands previously
determined to be easy (Brookshire, 1976).
The response required from an aphasic person can
affect performance on an auditory comprehension test.
Response modality, choices, and scoring are some impor-
tant variables to consider. Most recent research in aphasia has recognized the necessity to avoid verbal
responses and to employ gestural responses, such as
pointing or manipulation of objects, when measuring auditory comprehension (Shewan, 1979; Goodglass &
Kaplan, 1972; 1983). Also the number of choices in a
response array can affect the difficulty of the comprehension task and an aphasic adult's chance score. With only
two choices, the chance score is 50% which is reduced to
25% when four choices are provided. The types of
response choices also influence task difficulty_ Selection
of "ball" from the array of "ball, house" is much easier
than from "ball, bat, wheel, doll". The former contains
only an unrelated decoy while the latter contains a semantic association, a perceptual similarity, and a phonetic
similarity.
The scoring system employed in an auditory com·
prehension task can determine the amount and quality of
information obtained. While accuracy scores are important, multidimensional scoring systems provide more
information. The 16-point PICA scale measuring accuracy, responsiveness, completeness, efficiency, and
promptness (Porch, 1967) is a good example. This kind of
system is not without its drawbacks, however, as outlined
by Silverman (1974).
The psychological dimension can be divided into
motivation, intelligence, and memory variables. As a
speaker interacting with an aphasic patient, one can
motivate better performance. With positive instructions,
Stoicheff (1960) found that aphasic patients performed
better; with negative expectations, they performed
poorer. The patient's own intrinsic motivation is also
important, but it is a difficult variable to quantify empirically. Clinical experience, however, repeatedly tells us
that motivated patients generally do better in treatment
than un motivated ones.
Although aphasia does not cause intellectual
impairment, it is important to consider an aphasic
patient's premorbid intellectual level when selecting goals
and materials for rehabilitation. To state the obvious, it is
inappropriate to use materials that exceed a patient's
premorbid intellectual level. Whether a sentence is
understood also depends, to some extent, on the constraints it imposes on memory. Auditory memory factors
play a role in an aphasic patient's ability to decode, retain,
and recall verbal material. However, specifying and quantifying exactly how memory influences understanding is
difficult, especially since measures of memory have
frequently used unrelated items. Numbers are unrelated
in an auditory digit span task, and may be processed
differently from related items, words in sentences.
Many aphasic patients have more difficulty accurately comprehending nonredundant material with highly
concentrated information content than sentences of
equivalent length in which the information content is distributed throughout (DeRenzi & Vignolo, 1962). Part of
the difficulty may arise from "chunking" or "clustering"
Human Communication Canada/Communication Humaine Canada, Vot 9, No. 5, 1985
153
problems that reduce the amount of information an
aphasic patient is able to process (TiIlman & Gerstman,
1977).
DeRenzi, E. & Vignolo, L.A. (1962). The Token Test: A sensi·
tive test to detect receptive disturbances in aphasics. Brain, 85,
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High emotional content of material has been found to
facilitate auditory comprehension (Boiler et al., 1979).
However, comprehension of affectively toned or melodically intoned sentences, which are neutral in semantic
content, was not superior to comprehension of normally
toned sentences (Wallace, Canter, & Shewan, 1980).
Also, familiar content can facilitate auditory comprehension. Severely impaired aphasic patients have been
shown to be able to follow familiar conversational topics,
but became confused and misunderstood less familiar
topics (Stachowiak et al., 1977). Interest and familiarity
probably interact with listener motivation and directly
affect it.
Derouesne, J. & Lecours, AR (1972). Two tests for the study
of semantic deficits in aphasia. International Journal 0/ Mental
Health, 1, 14·24.
Summary
Comprehension problems in the aphasic adult generally encompass understanding the meaning of the linguistic message; that is, they involve semantic and syntactic
processing. Explanations of these problems on the basis
of auditory perceptual disturbances are no longer widely
accepted. Although perception may be involved in some
cases, it is not the underlying explanatory factor in most.
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