SPEAKING WITH MANYTONGUES: 
SOME PROBLEMS IN MODELING SPEAKERS 
OF ACTUAL DISCOURSE 
John H. Clippinger, Jr. 
Teleos 
Cambridge MA 02138 
I. INTRODUCTION 
"It is as if our languages were 
confounded; when we want a thought, 
they bring us a word; when we ask 
for a word; they bring us a dash; 
and when we expect a dash, there 
comes a piece of bawdy." 
Lichtenberg 
Any discussion of natural language 
processing models eventually makes reference 
to the extent to which a particular model or 
class of models accurately describes an 
aspect of human language processing. While 
there has been considerable work done in 
natural language comprehending systems and 
subsequent discussion of their 
appropriateness as descriptive models, there 
has not been a parallel effort in the area 
of discourse generation. Moreover, most 
work done in language comprehension and 
generation systems has been highly 
restricted to very specialized speech 
situations, and has not seen as its primary 
objective the modeling of a specific speaker 
or listener. While there are good 
methodological reasons for working with 
restricted examples and limited domains, an 
argument can be made that such a restricted 
and normative focus can result in distorted 
notions about the character and complexity 
of natural speech generation and 
comprehension. 
In this paper I would like to break 
with some established practices in 
artificial intelligence and linguistics, and 
examine some of the properties of 
transcribed natural discourse in order to 
suggest the types of mechanisms and 
frameworks that might be most appropriate to 
a description of human discourse behavior. 
The paper consists of three parts: the first 
will begin with a brief analysis of a sample 
of a "therapeutic discourse" and then focus 
on some principal issues in modeling natural 
discourse; the following section will 
briefly describe the manner in which this 
particular discourse episode was modeled in 
the program ERMA, and the final section will 
discuss the limitations of my own approach 
and suggest others that may be more 
complete. 
II. AN EXAMPLE OF NATURAL DISCOURSE 
For all the work done in linguistics, 
it is only relatively recently that 
linguists -- especially sociolinguists -- 
have begun to look at actual language use. 
Like undergraduates in psychology 
experiments, there has been a tendency to 
use limited samples of speakers as data 
sources -- more often than not, linguists 
themselves. Although this trend is 
beginning to reverse itself, it nonetheless 
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has resulted in some distortions about the 
use and character of' language. For by 
solely focusing upon the grammaticality or 
well-formedness of an utterance, attention 
is often averted from the reasons a 
particular utterance was made, and why it 
took the particular form it did. Below is a 
fragment of a transcribed episode in 
therapeutic discourse which was used in 
constructing the ERMA model and which I 
believe, is rich in data about discourse 
behavior. 
You know, for some reason, I, huh, 
just thought about, uh, about the 
bill and payment agsin. That (pause 
2 seconds) that, uh (pause 4 
seconds) I was, uh, thinking that 
I -- of asking you whether it 
wouldn't be all right for (pause 2 
seconds), you know, not to give me a 
bill. That is, uh-I would 
(hesitates) since I usually 
by -- well, I immediately thought of 
objections to this, but my idea was 
that I would simply count up the 
number of hours and give you a check 
at the end of the month. 
Notice that the information content of 
this reques is quite limited; the patient 
wants to bill herself and pay by check at 
the end of the month. But this rather 
limited request is couched in a most 
extraordinary network of dubitatives -- "you 
know," "for some reason," "wouldn't be all 
right," "that is," "was thinking," etc. 
Similarly, the entire third sentence acts 
like a dubitative, and in effect was 
produced in anticipation of the therapist's 
reaction; obviously, the patient is worried 
about what her therapist might think. 
Notice too that the patient starts a 
sentence ("That is, uh-I would since I 
usually by-well,") and then initiaties 
another sentence. It is quite apparent that 
this particular speaker is monitoring most 
of what she says -- thinking about it, and 
then reacting to it. Moreover, she does not 
seem to know what she is finally going to 
say from the start, but modifies, qualifies, 
and corrects herself as she speaks. Hence 
she seems to be invoking a number of 
different and often contradictory criteria 
in her production of discourse. She doesn't 
so much generate discourse -- as that 
implies too neat and linear a process -- as 
she regulates it; she makes a statement, 
retracts it, qualifies it, and then restates 
it. In fact, as the remaining section of 
this discourse episode makes clear, she had 
only a limited understanding about why she 
made the request in the first place. It 
turns out that she initiated the request to 
reduce the formality of the therapeutic 
setting in order to facilitate "intercourse" 
between herself and the therapist. Not only 
would it appear that there are a number of 
different and conflicting control mechanisms 
operating during the course of discourse 
production, but also during its inception, 
when the notion of the request was first 
being considered. 
What I think that this example 
demonstrates is the extent to which 
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cognitive and linguistic behaviors are 
incredibly intertwined. For not only does 
the cognitive component itself appear to be 
fragmented and at odds with itself, but each 
of these fragments -- or control 
mechanisms -- seem to have access to 
linguistic knowledge, which they in turn can 
use for their own purposes. Hence entire 
constituents can be formed and inserted en 
masse, ("you know," "for some reason",) or 
entire sentences generated by relatively 
independent mechanisms. Moreover, similar 
linguistic items seem to have different 
meanings according to how they are used, and 
therefore would require multiple 
representations. For example, the first 
sentence is a type of foregrounding remark 
and was constructed to acquaint the 
listener, the therapist in this case, with 
the reason for a change in topic. The word 
"thought" here refers to a prior mental 
action of the speaker and differs 
considerably from the "was thinking" of the 
second sentence, which in this case acts as 
a qualifier or dubitative. Any intelligent 
system must of course know the difference of 
uses and hence, meanings, between the two. 
Moreover, the derivation of the two similar 
words would differ; the first one would be 
derived from the concept for thinking and 
psychology at that. But independent of such 
a move I am at a loss to see how discourse 
behavior can be adequately described at the 
linguistic level alone. 
III. THE ERMA MODEL OF DISCOURSE BEHAVIOR 
The ERMA (err-umm-ah) (Clippinger, 
1974; Brown, 1974), program Was written to 
simulate a speaker of a therapeutic 
discourse from beginning to end: the 
motivation of the discourse, its censoring, 
reformulation, expression, and 
introspection. The intent was to have a 
program which replicated the thought and 
discourse processes of the modeled 
speaker -- including her hesitations and 
mistakes. The program was initially written 
in CONNIVER (McDermott Sussman, 1973) and 
makes extensive use of two of its key 
features; methods and contexts. 
f~orm~-F~ve major "stages of the discourse 
ation au~_~, expression process were 
~identifiedi and represented a~ CONNIVER 
-~-6~ntex-t-s.-r- Calvin, Machiavelli, Cicero, 
Freud, and Realization. Each had their own 
programs and datums, and accordingly, often 
their own opinions about what should be said 
and how it should be said. The discourse 
therefore come from the cognitive component ~ stream, so to speak, has its source in a 
proper, whereas the second has more of a Y ~~cial_~r~.~ program which initiates topic 
thematic ~eaning and would be inserted as a ~.~ concepts T6Tac~on, and then flows through 
means of qualifying a statement. ~~eac~ of these contexts -- often back and 
forth before achieving its final expression. 
While it is quite possible to model or ~ When a concept (more will be said about what 
describe isolated instances of such ~ a concept is later) is placed within the 
examples, I am quite skeptical about the °~ ~,~alvin context, programs there examine that 
long term value of such models independent ~~oncept to determine its acceptability for 
of a more general framework or theory. ~~, expression. The concept can be censored 
There is, I believe, a need for more global right off or it can be passed on to the 
theories about what discourse is and does, .~ Machiavelli context with suggestions as to 
for without such a framework, there is a 
tendency for classificatory schemes to 
become too closed and too specialized and 
hence incompatible with related work. This 
is particularly true if the process of 
discourse formation is a highly 
interdependent one, as I believe it is, and 
decisions made at one level interact with 
those made at another. 
I rules, and forms are organized. This is particularly true of thematic information 
which is especially variable and sensitive 
i to the intentions and idiosyncracies of the 
speaker and his setting. Consequently, in 
order to understand why certain thematic 
forms were used, as against others, or why a 
particular form is appropriate in one 
I context and not another, it is necessary to 
understand both the multiple intentions of 
the speaker and the~s~ra~_n~s he or she 
felt were in effect. To some extent, to 
answer such questions entails a move from 
linguistlcs to psychology -- maybe analytic 
how it should be modified. For example, in 
the case of the discourse sample previously 
discussed, the motivating concept expressed 
a desire for intercourse with the therapist. 
This request is found to be unacceptable, 
and the reason given is the fact that the 
therapy situation is a formal one governed 
by the exchange of payments. Another 
program in Calvin then tries to see what 
A more global theory of discourse would 
by necessity have to take into account the i ~'~" ~ 
fact that discourse behavior is an| 
intentional activity which attempts to| 
affect some trade off between the speaker's| 
goals, his constraints, his competency, and| 
those of his audience. For it is within| 
this setting that the more manifest aspects 
of discourse or speech are cast and it is 
within this setting that linguistic options, 
would happen if the exchange relationship 
~r' ' were "negated" or eliminated. It sends this 
new concept to the Machiavelli context, who 
as a specialist in such matters, tries to 
figure out how this would be accomplished. 
Various programs there consider different 
possibilities, one of which is to ask the 
therapist not to give the patient a bill. 
This suggestion in turn is sent to the 
Cicero context to assess its possible impact 
upon the therapist. A program there says 
that it would shock the therapist and sends 
back the concept for further consideration. 
Once back in Machiavelli again, programs 
there, who specialize in reducing negative 
or shocking impacts of statements, make 
their suggestions as to how the request can 
be made, with a minimum of offense. It is 
at this point in the program that cognitive 
and thematic considerations becom@ mixed. 
For although the program is stlrl worklng 
with concepts, which may or may not have 
acceptable lexical realization, it is making 
suggestions as to how the concepts should be 
marked for expression and how certain 
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qualifying constituents can be inserted to 
modify the listener s interpretation. These 
suggestions are then again sent to the 
Cicero context, where barring no further 
objections, they are made into state 
concepts and sent onto the Realization 
context for lexical realization and 
ordering. However, even after lexical 
realization is completed, the possibility 
exists for further interruption and 
reformulation, as Calvin has one final look 
at what is to be said. He can either stop 
an expression altogether, for example, where 
the patient starts to say "I shouldn't be 
given a bill" but stops herself and instead 
says "of asking you whether it wouldn't 
be...", or he can make last minute 
suggestions, which in turn are translated by 
special programs into interjections such as, 
"you know," "huh," "I mean." 
In order to produce even this limited 
discourse the program had to be able to 
distinguish between several levels of 
cognition: thinking about how to achieve a 
particular goal (irrespective of whether it 
would be realized into discourse); thinking 
about what to say (a state concept) and 
thinking about how to say it (lexical 
realization). At each of these levels 
different points of view were involved; 
Calvin regularly objected to what Cicero 
found acceptable, and Machiavelli, though 
apolitical, often found himself caught in 
between. If one adds in the Freud context, 
used for introspection, then the clash of 
opinions can become all the more strident. 
While it is doubtful that all forms of 
discourse behavior involve such a multitude 
of personalities and agents, it is apparent, 
I believe, that discourse can be produced 
from a number of different sources and that 
higher level cognitive decisions effect 
lower level linguistic decisions and vice 
versa. 
Since the discourse production process 
was found to be so diverse and interactive, 
it was absolutely necessary to have an 
extremely flexible means for representing 
concepts. The basic notion is similar to 
that of frames (Minsky, 1974; Winograd, 
1974) where a "generic concept" is used to 
represent a general or stereotypic meaning 
and a "token concept" is used to represent 
an instantiation of the generic concept. 
House, for example, would be treated as the 
generic concept, and the big red house would 
be the token concept where "big" and "red" 
would be concepts on the property list. 
Information about what the concept was would 
be carried on one set of indicators such as 
CHARACTERISTIC, and how it was to be used by 
another, DENOTER, PROCESS, DE-EMPHASIZE, 
STRESS, etc. Similarly, information about 
concepts" relationship to other concepts 
would also be represented by indicators and 
their property lists: RELATED-CONCEPT, 
MOTIVATION, CAUSE, EFFECT, UNACCEPTABLE, 
etc. In all, about thirty different types 
of indicators were used. 
Token concepts could be combined 
together to form "conceptual clauses," where 
a process or "relator" concept occupied the 
primary position and all other concepts 
70 
filled the slot of arguments specifying a 
role with respect to the relator concept. 
These conceptual clauses could become 
arbitrarily complex where each argument 
could potentially contain other embedded 
conceptual clauses. Consequently, it was 
quite possible for the program to contain a 
thought which could not be expressed with 
the same meaning it had internally. 
All processing of concepts is performed 
by a modified form of CONNIVER methods 
called multiple body interrupts developed by 
Richard Brown (Brown, 1974). They are fired 
when a concept's particular pattern matches 
their invocation pattern within a given 
context. Therefore control within the 
program is transferred through the sending 
and receiving of concepts and the addition 
and removal of property lists and 
indicators. For the most part, the 
intelligence of these programs is very 
specialized, as they only worked with token 
concepts for relatively specific purposes. 
Certainly if the program were to be expanded 
and generalized, these programs would also 
have to be generalized, but how much I am 
uncertain. For example, it might be 
tempting to have one program perform all 
foregrounding. However, I think that this 
would be disadvantageous in the long run, as 
the type of foregrounding required in 
discourse seems to vary according to the 
context in which the statement is being 
prepared, and therefore should be performed 
locally. 
The organization of the grammar, I 
believe, also demonstrates the extent to 
which cognitive and linguistic factors are 
interdependent. Initially, I had planned to 
use Halliday's systemic grammar (Halliday, 
1968), as I found his functional 
representation of grammar, and especially 
his work on thematic structure to be 
consistent with my own thinking about 
discourse structure. However, as I began to 
adapt it to the model I found that his level 
of description was inappropriate to what I 
was attempting to do. The first problem was 
that it was not conceptually based, and 
therefore too tightly wedded to a rather 
closed description of linguistic structures 
at the clausal level. The second problem 
was that his descriptions of thematic 
structure were not strictly functional, and 
therefore rather than supplying information 
about how a particular construction could be 
used to achieve a particular effect, they 
instead told what it was. Information about 
whether a particular concept is given or new 
within the ERMA program, for example, is not 
given a priori but supplied through feedback 
by audience sensitive programs that comment 
on what the audience knows or can be 
expected to know. Consequently, if the 
program is acting half way intelligently and 
tracking on what it is saying, it will take 
care of matters such as topic and comment 
implicitly. It is my belief that notions 
like theme and rheme, topic and comment, and 
the alike are only known upon reflection 
about what has been said, and essentially 
are tangential to the interests of the 
speaker while speaking. The grammar I ended 
up designing is conceptually based, and 
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while borrowing from Fillmore's notion of 
cases (Fillmore, 1968), employes a 
classification scheme which is ordered 
according to the effects various linguistic 
options achieve rather than simply what they 
are. 
Con.iectures and Conclusions 
While the study of discourse structure 
and cognition is now being actively pursued 
by linguists (Hymes and Gumperz, 1972; 
Labov, 1975; Lakoff, 1971; Halliday, 1973), 
philosophers (Ricoeur, 1970, Searle, 1971), 
and computational linguists (MacDonald, 
1975; Hayes, 1973; Schank, 1974; Philips, 
1973, Schmidt, 1973), there have not to my 
knowledge been any models developed which 
attempt to model the discourse behavior of a 
specific speaker. As a consequence, it is 
difficult to place the ERMA model or theory 
within any given paradigm of research on 
discourse, as the frameworks, objectives, 
and methods within this field are as nearly 
varied as the people working in it. 
Moreover, it is my belief that computational 
linguistics -- not to mention discourse 
simulation -- has yet to find its paradigm, 
for there remains a welter of data yet to be 
organized or explained, and no overriding 
consensus as to how it should be done. 
Therefore seen from this light, a 
discussion of the limitations and the goals 
of the ERMA model assumes a somewhat 
different cast, as I believe that the local 
and more technical decisions made in 
developing the model are of less relevance 
to an integrated understanding of human 
discourse than are some basic theoretical 
decisions which were made. For at present 
there is no basic methodological consensus 
on how discourse should be described -- or 
even what it is, for that matter, and hence 
any subsequent discussion of mechanisms 
alone would be, I believe, ungrounded. 
Therefore, I first want to make clear my own 
theoretical inclinations and then discuss 
some of the approaches of others to see how 
disourse behavior can be more 
comprehensively represented. First off, I 
regard the discourse process as a regulatory 
one, whereby the speaker attempts to achieve 
some effect through his communication of the 
medium of language. In speaking he has 
intentions as well as counter-intentions 
which he attempts to realize under the 
constraints of his own intellectual and 
linguistic competency as well as those of 
his listener. He can listen to what he 
says, and he can modify what he says at 
virtually any point in the discourse stream. 
He makes his linguistic selections according 
to the communicative effect he feels they 
will have; hence he is less concerned with 
the grammaticality or well-formedness of his 
utterance than with their effectiveness; in 
fact he might find being ungrammatical an 
effective means of expression. Moreover, he 
can be inventive as he speaks and listens, 
devising more abbreivated and specialized 
expressions according to context and intent. 
In developing the ERMA model I 
attempted to embody as many of these notions 
of discourse behavior as possible, but I 
71 
found that as I got further into working out 
a representation of the processes involved 
in producing the sample text, that I needed 
more empirical evidence for my modeling 
decisions. For example, why does the 
speaker hesitate at a particular point and 
not another, or why does she use "I mean," 
as against "You know," or how do I know that 
her request for a change in the billing 
arrangement is really a displaced request 
for intercourse? While I did examine other 
transcripts, roughly two hundred of them, to 
detect patterns, I lacked a sufficiently 
developed framework to really organize and 
focus my search. This lack of both 
empirical evidence and a more comprehensive 
and systematic understanding of discourse 
behavior in general led me to represent some 
of the discourse mechanisms and processes in 
a somewhat ad hoc fashion. For example, for 
the purposes of a general theory, it would 
have beendesirable to segregate in more 
detail the different possible stages of 
discourse formation and production and be 
able to justify these distinctions on sound 
theoretical or empirical grounds. 
Similarly, I would have liked to have had 
some basis for classifying the types of 
roles indicators play, and hence provide a 
more general understanding of their part in 
shaping discourse. But as it were, there 
were so many sizable gaps in my knowledge 
about natural discourse that it was far too 
easy to make any number of simplifying, if 
not erroneous, assumptions about how 
discourse was formed and produced without 
any immediate penalty. 
Consequently I would like to make an 
argument for more empirical research into 
the character of natural-unedited discourse, 
preferably those forms of discourse that 
exhibit mistakes and errors. I think that 
such inquiries in turn will provide a basis 
for designing and selecting the 
representational structures and procedures 
appropriate to model natural discourse. 
Certainly this cannot be done independent of 
some more general computational theory, but 
it is critical that this theory be not too 
specified or closed to preclude a full view 
of discourse data. 
Finally, I would like to briefly 
comment on two recent approaches in 
artificial intelligence which might begin to 
fill in the gaps in my own work. One of the 
hazards of research in this area is that by 
the time you complete your work someone else 
has already come up with an improvement on 
your own ideas. The notion of frames 
(Minsky, 1974; Winograd, 1975) is a case in 
point. Although ERMA uses a knowledge 
representation similar to that of frames, 
her cognitive skills are too specialized and 
too localized; she is quite incapable of 
making inferential loops. Moreover, the 
ERMA model has no systematic overall 
organization to her belief system, and 
hence, it is difficult at times to visualize 
from a distance what is taking place. There 
is also the question as to whether the 
production of discourse is best organized 
according to relatively set contexts, such 
as Machiavelli and Calvin, or whether the 
concepts themselves should determine their 
own formation and production contexts. I 
can see how something like a frame's 
representation might be able to resolve some 
of these problems because of its means for 
integrating general and specific knowledge. 
But exactly how I am uncertain. Perhaps, 
instead of having the program think in terms 
of concepts, it would think in terms of 
frame systems, which in turn would carry 
their own opinions as to how the discourse 
should be expressed. Similarly, these frame 
systems would be a part of larger frame 
systems, which would ovesee the overall and 
more general aspects of discourse 
regulation. 
I would also like to adapt some key 
notions of Sussman's model of skill 
acquisition (Sussman, i973) to a discourse 
model, as I feel that the process of 
producing a discourse and acquiring a skill 
-- albeit manipulating blocks, are 
intrinsically similar. Morever, his notions 
of representing actions in terms of their 
effects as well as his treatment of learning 
as a feedback process involving debugging 
and patching procedures, is similar in kind 
to my own notion of discourse production as 
a feedback regulated process. However, the 
added advantage of his approach is that the 
knowledge that his model has or acquires is 
a function of its own experience. This is 
substantially different from ERMA, where her 
knowledge is not learned to any substantial 
degree but programmed in from the start. 
This I feel to be a basic limitation, as it 
is my belief that at least part of an 
understanding of what discourse behavior is 
entails understanding how it was derived; 
especially, if one is concerned with the 
more subtle psychological factors that 
underlie therapeutic dicourse. For example, 
the manner in which the discourse formation 
contexts and procedures are organized 
reflect the learning and the experience of 
the speaker over time. Consequently, if we 
are ever going to adequately explain the 
organization of a discourse formation 
process of a real speaker, we are going to 
have to be able to identify those mechanisms 
which generated the discourse procedures and 
contexts in the first place. This is not 
just because it would be nice to have a 
means of describing the evolution of 
discourse styles and conventions over time, 
but because a single speaker will in the 
course of speaking use such deeper level 
mechanisms to both invent and to interpret 
new discourse. 
In conclusion, I would like to 
encourage the developement of more 
comprehensive computational theories of 
discourse that link diachronic descriptions 
and concerns with synchronic ones. If this 
is done with sufficient empirical content, I 
feel it is quite possible to create good 
descriptive and perhaps even predictive 
models of human discourse behavior in the 
near future. 
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