Download Lexical representations in spoken language comprehension

LANGUAGE AND COGNITIVE PROCESSES, 1988,3(1) 1-16
Lexical Representations in Spoken
Language Comprehension
William Marslen-Wilson
Max-Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
and M.R. C. Applied Psychology Unit, Cambridge, U.K .
Colin M. Brown
Max-Planck Institute for Psycholinguistics, Nijmegen, The Netherlands
Lorraine Komisarjevsky Tyler
Department of Experimental Psychology, University of Cambridge,
Cambridge, U.K .
This study investigates the timing with which lexical representations are
deployed at different levels of the language system, contrasting linguistic
aspects of verb argument frames with their consequences for interpretation in
the domain of non-linguistic, conceptual models. The experiment examined
monitoring latencies to noun targets that were either normal with respect to
the preceding verb, or which violated either pragmatic, semantic, or categorial constraints imposed by the verb’s argument frame and its associated
co-occurrence restrictions. The results show that syntactic and semantic
constraints derived from the verb have immediate effects on processing, and
that there is also a very rapid projection of the thematic properties of verb
argument frames on to non-linguistic domains of interpretation and inference, involving the listener’s mental model of the discourse.
I NTRODUCTION
The comprehension of a spoken utterance requires the listener to integrate
together a variety of different types of linguistic and non-linguistic knowledge. In particular, the linguistic properties of the utterance-its acoustic-phonetic, lexical, syntactic, and semantic properties-must
in some
way be mapped onto a mental model of the current discourse, taking into
Requests for reprints should be addressed to William Marslen-Wilson, M.R.C. Applied
Psychology Unit, 15 Chaucer Road, Cambridge CB2 ZEF, U.K.
0 1988Lawrence Erlbaum Associates Ltd. & V.S.P. Publications
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MARSLEN-WILSON, BROWN, TYLER
account the listener’s general non-linguistic knowledge of the world. It has
become increasingly evident , from developments in linguistics, psycholinguistics, and computational linguistics, that lexical representations play a
central role in this process of integration. Not only do lexical representations provide the basic bridge between sound and meaning, linking the
phonological properties of word-forms with clusters of syntactic and
semantic attributes, but also they provide the basic structural framework in
terms of which the linguistic representation of the utterance is constructed,
and in terms of which this linguistic representation is projected on to an
interpretation in a mental model.
In the research reported here we exploit the diverse properties of the
argument frames associated with verbs, in order to examine the basic
timing with which lexical representations are deployed at different levels of
the comprehension process, and in order to assess the relative importance
of these lexically based processes at each level. We begin with a brief
summary of the linguistic and psycholinguisticbackground to this research.
Background
The psycholinguistically most influential analysis of the properties of
lexical representations is still Chomsky’s (1965) treatment of the cooccurrence constraints associated with a given lexical item. In a complex
analysis of how these constraints could be expressed as part of the base
component of a transformational grammar, he distinguished two major
types of context-sensitive subcategorisation rules. Strict subcategorisation
rules specify the categorial context in which lexical entries can occurstating, for example, that a verb like grow can be followed either by an NP,
by an Adjectival form, or by nothing (in its intransitive use). Selectional
rules further subcategorise lexical items in terms of the syntactic features of
the items that can fill the categorial possibilities specified by the subcategorisation rules. By syntactic features, Chomsky meant properties such as
[*Animate] or [+.Abstract], which in later treatments have usually been
classified as semantic in nature (e.g. Jackendoff, 1972).
All subsequent analyses of the properties of lexical representations have
preserved, in one form or another, this fundamental distinction between
the categorial properties of the verb argument frame and the semantic and
syntactic properties of the items that can fill these argument slots. And,
certainly, to develop a psycholinguistic model of how lexical representations participate in language comprehension, it is necessary to capture in
some way the processing implications of such a distinction. When a
verb-form is identified, what kinds of subcategorisation and selectional
constraints are made available, and when and how do they affect the
processing of the subsequent input? These are questions that have received
LEXICAL REPRESENTATIONS IN SPOKEN LANGUAGE COMPREHENSION
3
surprisingly little attention in psycholinguisticresearch. Scattered attempts
were made in the early literature (e.g. Downey & Hakes, 1968; Fodor,
Garrett, & Bever, 1968; Hakes, 1971; Moore, 1972) to explore some of the
processing consequences of Chomsky’s proposals for lexical representation, but the results of these studies were contradictory and inconclusive.
Recent developments in the linguistic analysis of lexical representations
make their processing implications all the more salient for an on-line
theory of language comprehension. Essentially every major initiative in
generative linguistics over the past decade has served to move lexical
representations into a central position in determining the syntactic and
semantic properties of a string-indeed, as Wasow (1985) remarks, clause
structure has come to be viewed as a projection of lexical semantics. For
example, in both the Government-Binding approach (Chomsky, 1981; van
Riemsdijk & Williams, 1986) and in Lexical Functional Grammar (Bresnan, 1982), lexical representations determine the basic relations between
elements at both syntactic and semantic levels of the theory. GovernmentBinding achieves this through the combined effects of the Theta-Criterion
and the Projection Principle, operating on the argument structures associated with verbs, whereas Lexical Functional Grammar assumes that lexical
entries have a dual specification, pairing predicate argument structures
with specifications of grammatical functions. The grammatical functions
associated with lexical items map on to a syntactic constituent structure,
whereas the lexical predicate argument structure determines the functional
structure of the string, which in turn determines its semantic properties at
the appropriate level of representation.
What is important about these developments is the closeness with which
they link the subcategorisation properties of a lexical item with its argument structure in a semantic representation. The argument frames associated with lexical items specify not only how these arguments might
function in a purely syntactic representation of the string, but also in its
semantic interpretation. And it is this semantic interpretation that determines, in turn, how the string is projected on to a discourse model. In
effect, on this type of enriched account of lexical representations, the
argument frames associated with verbs have consequences not simply for
the linguistic analysis of an utterance, but also for the construction of an
interpretation in the non-linguistic, conceptual domain (c.f. Carlson &
Tanenhaus, 1987).
But even in this current linguistic climate of emphasis on the importance
of the lexicon, the on-line processing functions of lexical representations
remain relatively neglected-especially in the auditory domain. A number
of studies have begun to appear looking at lexical effects in the parsing of
written texts. These range from questionnaire studies (e.g. Ford, Bresnan,
& Kaplan, 1982), to studies using more on-line measures (e.g. Clifton,
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MARSLEN-WILSON,BROWN, TYLER
Frazier, & Connine, 1984; Mitchell, 1987; Mitchell & Holmes, 1985;
Tanenhaus, Stowe, & Carlson, 1985). All of these studies show that
lexical “preferences”-the relative salience of different subcategorisation
frames associated with the same word-form-have an immediate effect on
subsequent structural processing. But in the auditory domain, as far as we
are aware, there is no research which has looked explicitly at the on-line
recognition of verb-forms and the activation of their associated argument
frames.
The research which seems most relevant to the current study is some
research of our own which did not directly vary lexical variables at all. This
was an experiment (Marslen-Wilson & Tyler, 1980) designed to track the
time-course with which different types of processing information-globally
defined as syntactic and semantic-became available as listeners heard a
spoken utterance. The subjects monitored for word-targets at different
serial positions in three kinds of prose material: Normal Prose, Anomalous
Prose, and Scrambled Prose. Anomalous Prose differed from Normal
Prose in having no semantic organisation while preserving syntactic and
prosodic structure. Scrambled Prose differed from both in having neither
syntactic nor semantic organisation. These three types of test materials
were presented either as isolated sentences, or in the context provided by a
preceding lead-in sentence. The pattern of monitoring responses across
word positions for the three prose materials led to a view of sentence
processing in which, from the first word of an utterance, the syntactic and
semantic properties of the incoming speech are immediately interpreted in
the context of the current discourse model (Marslen-Wilson & Tyler, 1980;
1981).
These global claims about the properties of on-line language processing
have a rather direct interpretation in the lexical domain we have been
discussing and, certainly, the enriched functions that are being associated
with lexical representations make it easier to see how the speech input can
be interpreted as it is being heard. They imply that as a lexical entry is
accessed, this immediately makes available information about its argument
frame and places syntactic and semantic constraints on the types of
elements that can fill these slots. These argument frames are specified in a
way that has immediate consequences not only for the local syntactic
relations of items in the string, but also for their thematic or functional
roles. This means that the elements that fill these argument slots are
assigned a value not only with respect to some putative level of syntactic
organisation, but also with respect to a semantic and ultimately pragmatic
interpretation. In the following section of the paper we describe an
experiment designed to establish how far lexical representations do make
available information or constraints that operate at these different levels,
and the timing with which these come into operation.
LEXICAL REPRESENTATIONS IN SPOKEN LANGUAGE COMPREHENSION
5
Local Violation of Lexical Constraints
In an earlier study (Marslen-Wilson & Tyler, 1980), the availability of
different types of processing information was evaluated using global distortions of complete texts-as, for example, in the overall contrast between
Normal Prose and Anomalous Prose. The problem with this technique is,
first, that it rules out the possibility of looking at the processing information made available by any specific lexical item and, secondly, that it makes
it difficult to decide exactly what are the types of information of which a
global distortion is in fact depriving the listener (cf. Cowart, 1982; Marslen-Wilson & Tyler, 1983). Marslen-Wilson & Tyler (1980) presented the
contrast between Normal and Anomalous Prose as a difference in semantic
interpretability, but without systematically dissociating this from pragmatic
interpretability. Furthermore, as Cowart (1982) points out, Anomalous
Prose may have contained violations of syntactic constraints as well as of
semantic constraints.
These problems are avoided by looking at the local violation of lexical
constraints in otherwise normal sentence contexts. Specifically, by holding
the sentence constant, and varying the properties of the verb, we can
determine how and when different aspects of the verb’s argument frame
affect the processing of a spoken sentence. Take as an example the
following set:
la.
lb.
lc.
Id.
John carried the guitar.
John buried the guitar.
John drank the guitar.
John slept the guitar.
These are four identical strings, all with the same monitoring target
(guitar), where the only variation is in the verb, and in the argument
frames associated with the verb. In so far as these variations involve
properties of lexical representations that are significant for on-line processing, then they will affect the listener’s response to the monitoring target.
In sentence (la) the relationship between the verb (carried) and the
target (guitar) is fully acceptable on syntactic, semantic, and pragmatic
grounds. The subcategorisation requirements of the verb allow for a
nounphrase as direct object, a guitar has the appropriate semantics for the
action of carrying, and carrying a guitar is a perfectly reasonable activity in
the context of a standard model of the world. Response times to targets in
Normal contexts like (la) form the baseline condition for the experiment.
Sentences (lb) and (lc) illustrate two grades of potential violation of the
lexical representations evoked by the verb. In both cases the target NP
(guitar) remains categorially appropriate-the verbs are transitive and
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MARSLEN-WILSON, BROWN, TYLER
accept a nounphrase as direct object. Sentence (lb), however, constitutes
what we will label a pragmatic anomaly, and contrasts with (lc), which
constitutes a semantic anomaly. This, in effect, is the distinction between
the linguistic and the non-linguistic aspects of the lexical representation of
a verb. The anomaly-or the “oddness”-of “John buried the guitar”
cannot be part of the linguistic specification of the semantics of the lexical
items involved. In fact, it is not something that is likely to be pre-stored at
all. The pragmatic oddness of burying a guitar is something that we have to
infer, given our knowledge of the world, and given what we know about
guitars, the likely effects of burying them, and so on.
The first question we ask here, therefore, is whether such pragmatic
violations affect the on-line response to the monitoring target-that is,
whether responses are slower than in the normal condition. This will only
be the case if the response in the normal condition reflects, at least in part,
the pragmatic normality of the actions or events involved. And this, in
turn, can only hold if the lexical representations associated with the verb
have already begun to have consequences for an interpretation in a mental
model of the discourse. This requires, we should remember, not only the
construction of a linguistic argument frame, realising the structural constraints on the relationship between the verb and its potential arguments,
but also the projection of the thematic consequences of these relations into
the non-linguistic domain.
The second type of violation, in (lc), can plausibly (though not necessarily) be treated as a violation of the linguistically specifiable properties of
the lexical representations associated with a given verb-a violation, in
Chomskian terms, of the selection restrictions on the semantic properties
of the items that can fill the argument slots made available by the verb’s
subcategorisation properties. It is plausible that the linguistic specification
of drinking (that it involves liquids) and of guitars (that they are solid
objects) is sufficient to make guitar anomalous following drink without
having to invoke knowledge or operations outside the linguistic domain.
That is why we refer to this as a semantic rather than a pragmatic violation.
Our second question, therefore, is twofold: Are semantically anomalous
targets responded to more slowly than normal targets, and are they also
responded to more slowly than pragmatically anomalous targets? If the
first of these holds, then this reflects the timing with which the semantic
restrictions associated with argument frames start to become available, and
begin to be integrated with the semantic properties of potential fillers for
these slots. If the second of these holds, and semantic anomalies are more
disruptive than pragmatic anomalies, then this tells us something about the
relative significance, for the on-line analysis process, of these two types of
disruptions (we will return later in the paper to the question of how far
semantic and pragmatic anomalies can be kept qualitatively distinct).
LEXICAL REPRESENTATIONS IN SPOKEN LANGUAGE COMPREHENSION
7
Finally, we can also predict that if the original difference between Normal
Prose and Anomalous Prose in Marslen-Wilson and Tyler (1980) was
indeed equivalent, as originally intended, to violations of semantic cooccurrence restrictions, then the reaction time difference between Normal
and Semantic targets here should be of the order of 55-60 msec.
The third type of sentence, exemplified in (Id), differs from the other
two in violating the subcategorisation frame associated with a given verb.
A verb-form like sleep is subcategorised as an intransitive verb, and has no
subcategorised argument slot into which a nounphrase like guitar can fit.
This categorial violation should be highly disruptive of monitoring performance. The target nounphrase will be heard in the context of a verb
argument frame to which it cannot be attached. This means that the
listener cannot construct the appropriately configured structural object for
projection on to any other domain of interpretation. The collocation of
sleep and guitar simply has no interpretation, either semantically or pragmatically. This means that the monitoring decision that the word guitar is
present can be based only on the bottom-up sensory input. If the distinction here between semantic and categorial anomalies is equivalent to the
distinction in the earlier study (Marslen-Wilson & Tyler, 1980) between
Anomalous and Scrambled Prose, then reaction times in the categorial
condition should be on the order of 25-30 msec slower than in the semantic
condition, and about 90-100 msec slower than targets in the normal
sentences.
In a final manipulation, over and above the four primary contrasts
already described, we will investigate further the role of the discourse
model in these lexical activation processes, by comparing responses to
normal targets (as in la) when the test sentence coheres normally to its
preceding discourse context as opposed to cases where there is no coherent
relationship. When the utterance containing the target word cannot be
readily mapped onto the scenario established in the preceding sentence,
does this slow down responses? These are not, strictly speaking, local
violations, but we include them here in order to maintain comparability
with the earlier study, where we did find effects of the presence or absence
of a discourse context for target-positions early in the test sentence.
METHOD
Materials
The test materials consisted of 40 sets of sentence pairs. Each pair within
these sets was made up of a lead-in sentence and a continuation sentence.
The monitoring target always occurred in the second sentence, placed in
object position, immediately following the verb. Four kinds of continua-
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MARSLEN-WILSON, BROWN, TYLER
tion sentences were constructed by varying the relationship between the
verb and the target noun in the embedded verb-noun sequence. Within
each item set the target noun was kept constant. This gave the following
four anomaly conditions, together with one extra condition constructed by
varying the congruence of the lead-in sentence with the continuation
sentence:
1. Normal: Here the verb and the target noun form a natural sequence in
standard Dutch subject-verb-object order (e.g. “The boy held the
guitar”, where “guitar” is the target).
2. Pragmatic: Here the verb in combination with the target noun forms a
possible, but pragmatically implausible real-world situation (e .g. “The
boy buried the guitar”).
3. Semantic: Here the semantic properties of the verb are incompatible
with the semantic properties of the noun (e.g. “The boy drank the
guitar”).
4. Categorial: Here the verb forms a syntactically illegal combination with
the target noun. This was done by choosing intransitive verbs that could
not be followed by a noun in direct object position (e.g. “The boy slept
the guitar”).
5 . Discourse Congruence: A fifth manipulation applied to the Normal
continuation sentences only. Here the lead-in sentence was varied to
give either a natural or an unnatural discourse linkage with the continuation sentence.
The following example shows one complete stimulus set, with the
subjects hearing either lead-in sentence (1) plus one of the four lead-in
sentences (a)-(d), or lead-in sentence (2) plus continuation sentence (a).
Note that the original materials were in Dutch (the set given here is for
illustration only):
1. The nurses walk to their work each morning.
2. Christmas falls on a Friday this year.
a.
b.
c.
d.
They puss the beach on their way to the hospital.
They measure the beach on their way to the hospital.
They chew the beach on their way to the hospital.
They yawn the beach on their way to the hospital.
Pre-tests
The 40 sets of test materials were selected from a larger initial pool of 60
sets, on the basis of three types of pre-tests.
1. A predictability pre-test was run to ensure that the target nouns were
LEXICAL REPRESENTATIONS IN SPOKEN LANGUAGE COMPREHENSION
9
not easily predictable given the discourse sentences and the various pretarget verbs. Three sentence combinations were tested: the normal condition ( l a above), the discourse incongruence condition (2a above), and the
pragmatic anomaly condition (lb above). A total of 36 subjects were tested
in three groups, using a written cloze procedure, with items rotated across
groups such that no subject had to predict the same target word twice. The
subjects’ responses were scored on a 4-point scale. A scale value of 4
corresponded to responses unrelated to the target noun, 3 to responses
related to the target noun, 2 to responses that were synonyms of the target
noun, and 1to cases where subjects responded with the actual target noun.
The overall mean predictability ratings for the 40 test sentences was very
low for all three conditions-3.86 for normal, 3.91 for discourse incongruence, and 3.87 for pragmatic anomaly.
2 . A subcategorisation pre-test was run to ensure that the intransitive
verbs used in the verb-noun sequences did indeed exclude the possibility
of inserting nouns in direct object position immediately following the verb.
The same 60 sentence pairs from the predictability pre-test were used,
along with 30 fillers. The fillers contained sentences that did allow for the
use of direct objects. Twelve subjects read the neutral lead-in sentence
followed by the (d)-continuation sentence, up to and including the intransitive verb, and were asked to write down a continuation. They were also
asked to indicate on a 7-point scale whether or not they thought the
sentence pair-including their own continuation-was a natural one, both
with respect to grammar and meaning. Responses were checked for the
occurrence of direct objects. If direct objects were given along with a
natural rating, the sentence pair was removed from the stimulus pool. Very
few prospective stimuli failed this test.
3. In a naturalness pre-test, we tested the naturalness of the discourse
linkage between the lead-in and the continuation sentences (as well as the
unnaturalness of the linkage for the discourse incongruence pairs). Two
groups of 12 subjects were given 60 typed sentence pairs containing an
equal number of normal (la) and incongruent (2a) pairs. Subjects were
required to give naturalness judgements on a 7-point scale, with value 1
representing “very unnatural”, and value 7 representing “very natural”.
The mean rating for the final stimulus set was 6.35 for the normal pairs and
1.31 for the incongruent pairs.
Filler Materials
In order to distract subjects from the specific construction of the test
sentence pairs, 80 filler items were constructed. These also consisted of a
lead-in sentence and a continuation sentence. Three kinds of variations
were made on the filler items:
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MARSLEN-WILSON, BROWN, TYLER
1. Target position: The standard construction of the test continuation
sentences is subject-verb-target noun. In order to prevent subjects from
noticing the uniform position of the target noun, and the fact that all test
targets were nouns, we vaned both the word type and the word position of
the filler target. Filler targets could occur either in the lead-in sentence, in
the beginning of the continuation sentence, in the same position as the test
sentences, or late in the continuation sentence.
2. Anomaly of target: In the test sentence pairs, three out of the five
combinations have an anomalous target noun (lb, lc, Id). This could lead
subjects to believe that every anomaly is a target. To prevent this, most of
the fillers contained anomalous words which were not the monitoring
targets (as well as containing non-anomalous targets).
3 . Task: The experimental task for all test stimuli is identical monitoring. For the filler sentences two further tasks were used, namely rhyme
monitoring and category monitoring, in order to make the test situation
comparable to that used by Marslen-Wilson and Tyler (1980), and in order
to reduce the possibility that the subjects would develop special listening
strategies in carrying out the identical monitoring response. A total of 20
fillers were run using identical monitoring, 30 fillers using rhyme monitoring, and 30 fillers using category monitoring. This task distribution brought
the total number of items presented using identical monitoring up to 60 (40
test and 20 filler items), balanced by 60 filler items on rhyme and category
monitoring.
Practice Sentences
A total of 25 practice sentences were also constructed. These practice items
reflected all conditions and variations used in the test and filler sentences.
A further 10 filler items were constructed to serve as start-up sentences to
stabilise subject responses following the breaks after the practice session
and half-way through the test sequence.
Recording
The materials were recorded in a soundproofed booth, using a Revox A700
reel-to-reel tape-recorder, by a female speaker who was naive with respect
to the purpose and background of the experiment. All sentences were read
with a normal intonation pattern, without contrastive stress on either the
target words or their preceding verbs.
LEXICAL REPRESENTATIONS IN SPOKEN LANGUAGE COMPREHENSION
11
Design and Procedure
A total of 40 test sentence pairs were used under five conditions, along with
80 filler items, 10 start-up fillers, and 25 practice items. The 40 test
sentence pairs were rotated by conditions over five experimental versions,
with each experimental version having eight items in each condition. Each
target word occurred only once in each version, and each subject heard an
equal number of targets in each of the five test conditions. The five
experimental versions were made by cross-recordingfrom a master tape.
Procedure
The 40 subjects were tested in groups of 4. They were seated facing a
projection screen on to which was projected the slide specifying the
monitoring task for the next trial, and the appropriate cue word. Only the
“identical monitoring” task was used for the test stimuli, so that the cue
word was always the target itself. Thus, if the target was “beach”, the
subject would see the words “IDENTICAL” and “BEACH’. All the test
materials were presented over closed-ear headphones.
Each trial began with a warning tone that also triggered the projection of
the relevant slide. The sentence pair followed 3 sec later. The subjects
pressed a response button as soon as they detected the monitoring target.
They were instructed to respond as quickly as possible, to avoid guessing in
advance what the target word could be, and not to try to correct any
mistakes they heard in the sentences.
A complete experimental session, including instructions and practice,
lasted approximately 1 hour. Subjects were given a short break half-way
through the test sequence.
Subjects
A total of 40 paid student subjects participated in the experiment, of whom
20 were male and 20 female, and all were native speakers of Dutch.
RESULTS AND DISCUSSION
Eight subjects were run in each condition. There were 28 missing values
due to machine and subject error. A further 26 extreme values were set to
zero because they were well outside the range of the other data points in
the condition in which they occurred. These 54 missing and extreme values
(totalling 3.4% of the data) were replaced‘by the mean for the item in the
condition in which they occurred. Table 1 gives the main results for the
corrected data.
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MARSLEN-WILSON,BROWN, TYLER
TABLE 1
Item Means by Conditions (msec)
Normal
Incongruous
Pragmatic
Semantic
Categorial
241
235
268
291
320
Two separate one-way analyses of variance were computed, on subjects
and on items. The main effect of conditions was highly significant (min
F’(4,46)=16.678, P<O.OOl). Post hoc comparisons between conditions
were performed using the Neuman-Keuls procedure, with the error term
computed using the min F’ value (Clark, 1973). Table 2 lists the outcome
of these comparisons between the means.
Before moving on to the main body of the results, we should comment
on the absence of any effect of discourse incongruence. Response times
were unaffected by variations in the coherence of the test sentence with its
lead-in sentence. There are two likely reasons for this. The first is that the
lead-in sentences in the normal condition (la) were constructed to be very
neutral, so that the target word would not be predictable (as the predictability pre-test reflects). This would have minimised the effective differences
in facilitation between the normal and the incongruous conditions. Secondly, the evidence from our earlier study (Marslen-Wilson & Tyler, 1980) is
that the additional facilitation due to the presence of a discourse context is
only detectable over the first few words of the test sentence. The differential advantage deriving from the discourse context disappears as a result of
increasing within-sentence constraints. In the current study, all the targets
occurred in the fourth or fifth word-position, following the verb. This may
have been too late to measure any differential effects due to the discourse
variable.
We now turn to the first set of verb anomaly results-namely, those
involving pragmatic and semantic anomalies. The contrast here, as we
argued in the Introduction, was between anomalies that necessarily deTABLE 2
Comparisons Between Item Means (Newman-Keuls)
~~
Incongruous
Normal
Pragmatic
Semantic
Incongruous
Normal
Pragmatic
Semantic
Categorial
-
-6
-
-34*
-28*
-56**
-.SO**
-22
-86**
-79**
-52**
-29*
* = P < 0.05, * * = P < 0.01.
-
-
LEXICAL REPRESENTATIONS IN SPOKEN LANGUAGE COMPREHENSION
13
pended on non-linguistic aspects of interpretation and anomalies that did
not. A pragmatic anomaly-someone, for example, burying a guitarcould only exist as an anomaly on the basis of some form of inferential
computation, involving not only the lexical semantics of terms like guitar
and bury, but also more general knowledge of the world. A semantic
anomaly-someone, for example, drinking a guitar-could be instantiated
simply as a function of the stored linguistic properties of terms like guitar
and drink, without involving non-linguisticsystems of knowledge at all.
The empirical question we asked, then, was whether pragmatic anomalies did significantly affect the on-line response to the monitoring target, or
whether the effect was restricted only to the semantic anomalies. The
results show clear effects of each type of anomaly, with pragmatic anomalies (at 268 msec) and semantic anomalies (at 291 msec) both significantly
slower than responses to normal targets (241 msec). The effect for pragmatic anomalies means that the lexical representations associated with the
verb must be being interpreted on-line, not only within a linguistic system
of analysis, but also with respect to the listener’s mental model of the
utterance-that is, with respect to a level of representation which incorporates inferential processes operating on non-linguistic as well as linguistic
knowledge. This in turn is consistent with a view of lexical processing
which stresses the immediacy with which the thematic consequences of a
given lexical argument frame can be projected on to non-linguistic domains
of interpretation.
It is also worth pointing out that these conclusions hold even if one takes
the view of monitoring performance argued for by Tanenhaus, Carlson,
and Seidenberg (1985), in which the sorts of context effects described in
Marslen-Wilson and Tyler (1980) are re-analysed as a form of sophisticated
guessing. Even if this were the way that context effects are mediated, the
difference between normal and pragmatic conditions still requires the
on-line computation of the pragmatic plausibility that the target will appear
as the object of the verb in the two conditions. The listener’s estimate, on
the guessing account, of the likelihood that guitar will be the object of
bury, can only differ from the subjective likelihood following curry on the
basis of some form of inference process, dependent on the properties of the
actual verb being heard. These inferences would require the projection of
verb properties onto a non-linguistic domain, so that the pattern of
responses still remains as evidence for the immediacy with which this
projection takes place.
Turning to the effects for semantic anomalies, these confirm, first of all,
that semantic aspects of lexical representations are also immediately
activated in on-line processing. Secondly, the comparability between the
size of the effect for these stimuli (at 50 msec) and the effect for the
contrast between Normal Prose and Anomalous Prose in Marslen-Wilson
14
MARSLEN-WILSON, BROWN, TYLER
& Tyler (1980)-where responses to Anomalous Prose were 58 msec
slower-suggests that the effects in this earlier study were also due to
violations of semantic restrictions on co-occurrence relations. Thirdly,
there is also a tendency for the semantic anomalies to have a more
disruptive effect on responses than the pragmatic anomalies. Although the
mean difference of 22 msec is not significant using a min F’ based statistic,
it is significant on the Neuman-Keuls using error terms derived either from
the subject or the item analyses alone.
This indicates that an anomaly based on violations of semantic selectiona1 restrictions-as classically defined-will tend to be more disruptive than
an anomaly based solely on violations of contingent plausibility. This does
not, however, allow us to conclude that there is a qualitative difference
between the types of representation involved-that semantic anomalies
involve only disruptions within a strictly linguistic system of semantic
representation and analysis, whereas pragmatic anomalies necessarily take
us outside this domain. This is because the semantic anomalies are anomalous not just with respect to putatively language internal co-occurrence
restrictions, but also with respect to considerations of real-word plausibility. If it is unusual and implausible to bury a guitar, it is far more unusual to
drink one. And while one can easily construct a context in which burying a
guitar is perfectly plausible, it is far more difficult to construct a context in
which the act of drinking a guitar becomes possible or plausible. The
additional increase in response time for the semantic anomalies may reflect
these additional difficulties in the domain of pragmatic inference, rather
than difficulties at some other level of the system. The present research
does not allow us to discriminate between these possibilities.
The final aspect of the results concerns the categorial violations, where
the target noun appears in a position in the sentence that violates the
subcategorisation frame associated with the preceding verb. This has the
strongest effect on response time, with responses being significantly slower
than to the semantic anomalies, and some 79 msec slower than responses
to the same targets in normal contexts. We predicted these strong effects in
the Introduction, on the argument that this type of violation of subcategorisation constraints means that the listener is presented with a structurally
uninterpretable combination of lexical items. The target nounphrase is
heard in the context of a verb subcategorisation frame which contains no
argument slot into which it can be attached. This means that the listener
cannot construct the appropriate structural formation for projection on to
normal domains of interpretation. For the purposes of the monitoring task,
then, the listener can only have access to the monitoring target by treating
it as a word heard in isolation.
This interpretation is supported by the similarity in the size of the effect
of categorial violations here to the difference (of 85 msec) between the
LEXICAL REPRESENTATIONS IN SPOKEN LANGUAGE COMPREHENSION
15
Normal Prose contexts and the Scrambled Prose contexts in the MarslenWilson and Tyler (1980) study. In Scrambled Prose the subjects heard
targets in unstructured word-lists, constructed by scrambling the order of
Anomalous Prose sentences. Evidently, subcategorial violations have a
comparable effect, by depriving the target nounphrase of any kind of
systematic sentential context of interpretation.
The goals of this study, in conclusion, were to gather some basic
information about the timing with which different aspects of lexical representations could begin to have consequences for the processing of subsequent items in a spoken utterance. The results, looking at the effects of
violating the pragmatic, semantic, and structural restrictions deriving from
the argument frames associated with transitive and intransitive verbs, show
immediate effects both at strictly linguistic levels of interpretation (as
classically defined) and at levels of interpretation and inference relevant to
the listener’s construction of a mental model of the current utterance.
These are results that are consistent with approaches to language comprehension which stress its continuous and incremental nature (e.g. MarslenWilson & Tyler, 1987; Steedman, 1988; Tyler, 1988), and which emphasise
the role of lexically derived thematic roles in constructing these higherlevel interpretations (e.g. Tanenhaus & Carlson, 1988).
Manuscript received May 1987
Revised manuscript received February 1988
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