Page 76

 

 

(TYPICALLY (#STREP-SYMPTOMS FINOING
. AGN
(AND (STATUS PHARYNGITIS PRESENT)
(STATUS FEVER PRESENT)
(STATUS MALAISE PRESENT))))

(USUALLY (TIME-OF sSTREP-SYMPTONS
(AFTER (ONSET STREPTOCOCCAL-INFECTION)
"INTERVAL (DAYS 1.) (DAYS 5.220)

(ALNOST-RLUAYS (sAGN-SYNPTONS FINOING
AGN
(AND (NOT sSTREP-SYMPTONS)
(STATUS WEAKNESS PRESENT)
(STATUS ANOREXIA PRESENT) )))

(TIME~OF sAGN-SYMPTOMS
(AFTER (ONSET STREPTOCOCCAL-INFECTION)
CINTERVAL (WEEKS 1.) (WEEKS 2.))))

FIGURE 8. FRAGMENT OF THE AGN CONTEXT

NOTE:

For convenience, GOBBLE permits

expressions to be fabelled for later reference. Expressions beginning
with starred words are labeiled. The starred word is discarded,

but it is remembered as standing for the rest of the expression.
Later mentions of the name are replaced by the full expression.

We have used this convention in this Figure.
Privileged - i G.A.Gorry Qn Page 77

and it would have the tentative hypotheses of stone, renal tumor, etc.

We have begun to integrate GOBBLE into our various projects. For
example, we are planning to convert the present iliness program to this
system., and we are experimenting with the conversion of the formal
representation of clinical knowledge to this format. Also the
digitalis/digoxin advisor project is using GOBBLE in its preliminary
programming. Some further examples of. the use of GOBBLE will be
presented in the next section when we discuss the time specialist.

Building "Specialists"

Any expert system needs specialists in common sense knowledge. A
doctor in addition to needing medical knowledge must know rather
everyday things about time , location or quantities. During the process
of diagnosis the doctor must be able to understand that if a patient is
25 years old and he was told that when the patient was about 22 years

old he had a heart murmur, that it occured three years ago or during
1978-1971. .

The GOBBLE system also needs specialists. When asked if there is a
mention of edema of the face, the system must respond positively if
there is periorbital edema mentioned. This requires that the system
know that periorbital edema is located around the eyes and the eyes are
part of the face. Many such elementary deductions are required for

accessing a large knowledge. The question is how best to provide such a
facility.

One solution is to distribute the requirement for such deductions

through the system. Another solution, which seems much more promising
is to concentrate as much special knowledge about such matters as time,
location, etc. in isolated specialists, programs which are expert in

the rather shallow deductions needed. Our belief is that most of the
questions about time can be answered by a time specialist. The same

holds true for location, status, amount, etc. Undoubtedly there will be
special questions, in certain contexts, which may be beyond the
competence of the specialists, but we think that such questions wil! be
rare.

With these considerations in mind, a time specialist for was
developed as part of the GOBBLE framework. First a representation of
time expressions was developed. Two different time representations were
chosen to be as close to everyday usage as possible . One is absolute
time where the time is given as a date and a fuzz factor to describe the
uncertainty of the time of the event’s occurrence. The format is:

(TIME-OF <event> (DATE (19NN NN NN)
(FUZZ <days,weeks,months, years> NN)))

Where event is either an event such as "(STATUS EDEMA PRESENT)" or an
event preceded by either “beginning-cf" or "end-of". Beginning-of and
_ Privileged C

C.A.Corry Page ‘78

end-of are used to specify that an event occured over a period of time

longer than a day. If only the beginning-of an event is specified it is
assumed to be currently true as in "(BEGINNING-OF LIFE)" . The. fuzz is

simply the length of time from the date given, that one considers it

possible that the event occured and is used in the routines that search
the data base.

 

The other representation for the time of an event is more common in
everyday speech, that is the time is given relative to some other event
whose time is presumably known. Thus "25 years old" translates to
"(AFTER (BEGINNING-OF LIFE) (BY-AMOUNT (YEARS 25.) (FUZZ MONTHS 6.)))".
"Exactly three weeks ago" becomes "(BEFORE TODAY (BY-AMOUNT (WEEKS 3.)

NIL))". To express the fact that edema occured two weeks after a strep
infection one would GOBBLE:

(TIME-OF (STATUS EDEMA PRESENT)
(AFTER (STATUS STREP-INFECTION PRESENT)
(BY-AMOUNT (WEEKS 2.) (FUZZ DAYS 3.))))

What the Time Specialist Ooes

When a fact is GOBBLE’d in the relative time format the corresponding
absolute time is computed and GOBBLE’d, leaving the origina! alone. In
addition when. an absolute time is GOBBLE’d the event is put on a “time
line" which orders the events on a number line as either points or
segments. This time line is used by a function called "SEARCH" which
takes one or two dates in the form "(19NN NN NN)” and finds all events

that were true during that period regardless of whether they began or
ended between those dates. —

The other main interrogator of the data base is the function “TIME-
OF" which when applied to an event, a time specification identical to
that of the time specification for general non-fact rules, i.e. interval
instead of amount, and a context, returns the internal identifier of the
first fact it finds that meets the time specification which in the case

of non-fact contexts is found in that context and is matched in the
facts context. For example,

(TIME-OF * (STATUS EDEMA PRESENT)

"(AFTER STREP-INFECTION A-FEW-WEEKS)
*FACTS)

would return "nil" if edema was not a few weeks after the strep
infection otherwise the identity of the expression whose TIME-OF edema
matched. If the context were say, edema, then the time expression. would

be searched for in the edema context and matched in facts. (See Figure
9.)
Page 79

SSS SCCACSTSCCAEARSSCSKCSSHATCAKSAETTESTAASHSTACSTASTCTSTTSSLAKSTARTESSSLESTKES
2

The following is a sample conversation with the time specialist.
Lower case letters are typed by the user and upper case by the
the computer. Comments are precaeded by “#5 ",

when he was 21 years old he had a heart attack.

IF YOU THINK THE FOLLOWING IS RIGHT TREN RESPOND YES
AND IT WILL BE GOBBLED INTO FACTS.
(TIME-OF HEART-ATTACK (AFTER (BEGINNING-OF LIFE)
(BY-AMOUNT CYEARS 21.) (FUZZ MONTHS 9.9)))
sexe This is the Gobble: form translated from
aee% the English. After the present testing
axee Stage this will automatically be Gobbled.

THE TIME OF HEART-ATTACK IS WHEN THE PATIENT WAS 21. YEARS
GIVE OR TAKE 9. MONTHS OLD

wank This is the English paraphrasing of the
sexe Gobble form.

yes xezx The fact in now in the data base.
(cp ’ facts) wee This displays the "FACTS" context.

THE TIME OF HEART-ATTACK IS ABOUT JANUARY 25. , 1973.
GIVE OR TAKE 9. MONTHS
zaee The date was calculated and Gobbled by
etek the time specialist.
THE TIME OF HEART-ATTACK IS WHEN THE PATIENT WAS 21. YEARS
GIVE OR TAKE 3. MONTHS

THE TIME OF THE BEGINNING OF LIFE IS EXACTLY JANUARY 25. ,
1952.

three years ago he had edema.
eeex The system can presently accept a wide
#s%%x variety of ways of expressing when
*&t% something happened.

IF YOU THINK THE FOLLOWING IS RIGHT THEN RESPOND YES
AND IT WILL BE GOBBLED INTO FACTS.
(TIME-OF EDEMA (BEFORE TODAY

(BY-AMOUNT (YEARS 3.) (FUZZ MONTHS 9.))))
THE TIME OF EDEMA IS 3. YEARS GIVE OR TAKE §. MONTHS AGO

yes

BRIPSPSIOSSETEDPSESSTSIARSSS STASSAARSSSSSTSSARSSTSSSITSSE SA LASTTSLSISAARBEESOSEC=S

FIGURE S. Session With The TIME SPECIALIST
Page 80

(time-of *hear t-attack
"(before today (interval (years 2.)
(months 4.))) ’ facts)
«zee Here the computer is asked if
s%s%x the heart attack occured between
#%%% two years and four months ago.

YES, THE TIME OF HEART- ATTACK IS ABOUT JANUARY 25. , 1973.
GIVE OR TAKE S$. MONTHS

(auhy) see Here the system is asked why it
Se&% answered as it did.

I WAS ASKED IF THE TIME OF HEART-ATTACK WAS BETWEEN 2. YEARS
AND 4. MONTHS AGO

SO FIRST I TRIED TO FIGURE OUT WHAT YOU MEANT BY BETWEEN 2.
YEARS AND 4. MONTHS AGO

THE EARLIEST POSSIBLE TINE TODAY COULD HAVE BEEN IS 1974. 2.
27. AND THE LATEST POSSIBLE TIME IT COULD HAVE BEEN IS 1974,
2. 27.

I THEN FIGURED OUT THE DATES WHICH WERE BETHEEN 2. YEARS

AND 4. MONTHS BEFORE 1974. 2. 27. AND 1974. 2. 27.

WHICH WERE 1972. 2. 27. AND 1973. 18. 27.

THEN I CHECKEO TO SEF IF THE TIME OF HEART-ATTACK FELL INTO
THE RANGE BETWEEN 1972. 2. 27. AND 1973. 18. 27.

THE EARLIEST TIME HEART-ATTACK COULD HAVE HAPPENED IS 1972, 4.
25. AND THE LATEST IT COULD HAVE HAPPENED IS 1973. 18. 25.
SO I OECIDED THAT

THE TIME OF HEART-ATTACK PROBABLY WAS BETWEEN 2. YEARS AND 4.
MONTHS AGO ,

(setq time-of-talk-sw t) suze This tells the system to
axes "think outloud".

(time-of ’edema
(after (beginning-of life) (interval (years 28)
(years 18))) ’ facts)

I WAS ASKEO IF THE TIME OF EDENA WAS WHEN THE PATIENT HAS
BETWEEN 28. AND 18. YEARS OLD

SO FIRST I TRIED TO FIGURE OUT WHAT YOU MEANT BY

WHEN THE PATIENT WAS BETHEEN 20. AND 18. YEARS OLD

THE EARLIEST POSSIBLE TIME THE BEGINNING OF LIFE COULD HAVE
BEEN IS 1952. 1. 25. AND THE LATEST POSSIBLE TINE IT COULD
HAVE BEEN 1S 1952. 1. 25.

I THEN FIGURED OUT THE DATES WHICH WERE BETWEEN 28. YEARS
AND 18. YEARS AFTER 1952. 1. 25. AND 1952. 1. 25. WHICH
WERE 1978. 1. 25. AND 1972. 1. 25.

THEN I CHECKED TO SEE IF THE TINE OF EDEMA FELL INTO THE RANGE
BETWEEN 1978. 1. 25. AND 1972, 1. 25.

THE EARLIEST TIME EDEMA COULD HAVE HAPPENED IS 1970. S. 27.
AND THE LATEST IT COULD HAVE HAPPENED IS 1971. 11. 27. SO I
DECIDED THAT

THE TINE OF EDEMA PROBABLY WAS WHEN THE PATIENT WAS. BETWEEN
28. ANDO 18. YEARS OLD

FIGURE S. Continued
Note: Patient is Known to hava been born on

January 25, 1952, and the discussion is being heid
on February 27, 1976.
Privi | eget ERD C.A. Corry Page 81

Research on the Time Specialist and Other Specialists

Although the time specialist deals wel! with rudimentary questions
about time, some additional work is needed to expand its capabilities.
One of the. most important problems is to incorporate into it some

understanding of rates. For example, it should understand such
statements as

The onset of the disease is abrupt.
Usually the disease develops insidiously.

The hypertension subsides slowly after the diuresis.
etc.

Now it is clear that in certain circumstances, even doctors would have
difficulty saying exactly what these statements mean. So we are not
proposing to equip the time specialist with more than human expertise.
On the other hand, we can get very good agreement on what these
statements do not.mean. For example, if the symptoms of the disease
mentioned in the first statement appear over a two week interval, then
we would not call the onset abrupt. Similarly, we would not call the
development of a disease within a fen weeks insidious. The time
specialist should be aware of these distinctions, too.

It is very important to realize. that even rough definitions of these
concepts will allow the time specialist to answer @ great many
questions. People have developed these concepts and have used them
successfully because in most instances, their exact definitions do not
matter. If someone tells you that an event will occur "within a feu
days", you may find that acceptable, never ascertaining whether two
days, three days, or more is meant. The language of medicine is rich in
terms which are understood, but never precisely defined. In certain
instances, this lack of precise definition can be troublesome, but for

the most part, a rough idea, commoniy shared, of the meaning of the
concept is sufficient.

We propose to pursue our research on the time specialist and other
specialist with such a bias. The goal will be to equip each specialist
with just enough knowledge to permit areasonable discussion with a
clinician. The program should answer- the questions of the clinician
directly even when they contain vague phrases of the type mentioned
above. The goal is to have the specialist have trouble only when most
people would have trouble in interpretting a question.

In addition to the problems associated with rates, we want to look at
another important problem for the time specialist. This is the concept

of episodes. In a sense, this problem belongs in the domain of

representation work as well as here in the province of the time
specialist. In any event, the representation and understanding of
episodic disease is very important, and will require considerable

research before a good salution can be developed. Basically we need a
Privileged ‘el? G.A.Gorry fT Page 82

mechanism to describe the "prototypical" episode and the time intervals
between occurrences of episodes. For certain instances, this is quite
straightforward, but for other situations, this is quite difficult.
Because we have just begun to work on this problem, we cannot discuss it

further here, other than to note that it will receive careful attention
in the near future.

Inquiry and Expianation
The development of markedly improved facilities for inquiry = and

explanation is one of the central computer science research projects of
the proposed Laboratory. The importance of such facilities should be

recognized, because without them, it is doubtful whether a large,
knowledge-based program can be built for a complex clinical problem.
The construction of such a program will require three things:

1) understanding of the processes of clinical cognition
2) mechanization of a very large amount of knowledge
3) development of new programming concepts and technology

The achievement of the first two goals will require the close
collaboration of clinicians and computer scientists. The former must be
able to actively work with the computer realizations of the cognitive
theories, and they must also be able to explore the knowledge base of
the programs in use. Hence, the clinicians will need direct interaction
with the developing system. Further as the system grows, computer
scientists as well will meed such access. As the system grows in

complexity, it must be able to answer questions about its knowledge and
per formance. ‘

Further, if we look to the day in which such systems are introduced
into the health care system, we see the additional need for such
facilities. It is unreasonable to expect that clinicians will accept
advice from such a system about a serious problem without any access to
the knowledge or reasoning upon which the advice is based. In addition,
this explanation of the reasoning of the system must be in terms which
the clinician can understand.

So for our own immediate needs, and for the long run needs of the
field, we will actively pursue research in both inquiry and explanation.
Of the two, explanation will receive the most attention. The reason for
this is that other researchers at M.I.7. are vigorously pursuing natural
language research. This research has already led to significantly
improved parsers. We plan to adopt one of these parsers when it has
reached a satisfactory state of development. We plan to invest only
enough time and resources to assure that the special needs of an

interface designed for clinicians can be accomodated by the parser we
select.

As an example of this policy, consider the English language facility
used in the dialogue with the time specialist. The parser used there is
Privileged Communication G.A.Gorry a> Page 83

called LINGOL {19} and it was developed by Professor Vaughn Pratt of
M.1.T. We found that we could easily adapt it to our needs, and that it
provides us with a reasonable. interface. Certainly, there are problems
Which it doesn’t handle, but we will leave most all of these problems to
the language researchers. For the small effort involved in adapting it
to our needs, LINGOL has returned considerable benefit. Other language
research at M.1.T. may yield even better facilities. If so, we will be
able to further improve our interface with the clinicians, and thereby
improve our ability to achieve our research objectives.

The matter of explanation, however, is one to which we wil put more
effort. Because of its importance, and because it appears to be a
problem in which we are more interested than other computer science
researchers, we feel that we must take more of a lead in’ research. To

this end, we have undertaken the development of an explanation facility
to incorporated into GOBBLE.

Now the first issue to be considered is what constitutes an adequate

explanation. In certain instances, simply retrieving a fact may
suffice. In other cases, the explanation may require the use of a model
(e.g. of physiology). In still other cases, a dialogue may be required

to accomplish the task.

As a first step, we have developed a rudimentary "“explainer" for
GOBBLE. It gives simple explanations of relationships in a knowledge
base. An example of an interaction with this explanation program is
shown in Figure 18a, The program is following back through a causal
chain to produce an explanation of the findings of nephrotic syndrome.
Although it is not apparent from this particular interaction, this
program differs from one which has a "canned" response in that it can
enter this chain at any point as requested by the user. A more
interesting example of this capabitity is shown in Figure 1@b.
Page 84

 

AT ANY TIME YOU MAY ENTER THE QUESTION MODULE BY TYPING R ?
FOLLOWED BY A SPACE. A RETURNS TO PROGRAM.

I HAVE FOUND 2. POSSIBLE CONTEXTS

1. NEPHROTIC SYNDROME

2. GENERAL

WHICH OO YOU WANT TO REFERENCE ?

>>> i

EOEMA CAN OFTEN BE OBSERVED IN NEPHROTIC SYNOROME

THE BASIC CAUSE OF EDEMA IN NEPHROTIC SYNDROME IS MASSIVE PROTEINURIA
WOULD YOU LIKE TO KNOW MORE ?

>>> Y¥

EDEMA IS DIRECTLY CAUSED BY INCREASED INTERSTITIAL FLUID
WOULD YOU LIKE TO KNOW HORE ?

>>> Y

INCREASED INTERSTITIAL FLUIO IS OIRECTLY CAUSED BY RENAL SALT AND
WATER RETENTION ,

WOULD YOU LIKE TO KNOW MORE 7

>>> Y

I THINK THAT THERE ARE 2. POSSIBLE CAUSES OF RENAL SALT AND WATER
RETENTION ,

1. DECREASED GLOMERULAR FILTRATION RATE
2. INCREASED MINERALOCORTICOID SECRETION
WHICH WOULD YOU LIKE TO KNOW MORE ABOUT ?

>>> 2

INCREASED MINERALOCORTICOIO SECRETION IS DIRECTLY CAUSED BY
DECREASED PLASMA VOLUNE AND DECREASED CAROIAC OUTPUT

BY THE WAY DECREASED PLASNA VOLUNE ANO DECREASED CARDIAC OUTPUT
ALSO CAUSES OECREASED RENAL 8L000 FLOW

WOULD YOU LIKE TG KNOW MORE ?

>>> Y¥

IN NEPHROTIC SYNDRONE

DECREASED PLASNA VOLUNE AND DECREASED CARDIAC OUTPUT IS DIRECTLY
CAUSED BY DIFFUSION OF WATER AND SOLUTES TO INTERSTITIAL FLUID

FIGURE 10a. An explanation from the knowledge base
Page 85

WOULD YOU LIKE TO KNOW MORE ?

>>> Y.

DIFFUSION OF WATER AND SOLUTES TO INTERSTITIAL FLUID IS DIRECTLY
CAUSED BY DECREASED ONCOTIC PRESSURE
WOULD YOU LIKE TO. KNOW MORE ?

>>> Y

DECREASED ONCOTIC PRESSURE 1s OIRECTLY CAUSED BY HYPOPROTEINEMIA
WOULD YOU LIKE TO KNOW MORE ?

>>> Y

HYPOPROTEINENIA IS DIRECTLY CAUSED BY MASSIVE PROTEINURIA
BY THE WAY MASSIVE PROTEINURIA IS ASSOCIATED WITH
HYPERCHOLESTEROLEMIA AND LIPIOURIA

WOULD YOU LIKE TO KNOW MORE .?

>>> ¥

T 00 NOT KNOW ANY MORE

FIGURE 10a. Continued
Page 86

BUS SRETERAESRRERERTEELSRT AAC ASaescssssecessseseseseers SFT KSPR HELSETASAREX

YOU HAVE JUST ENTERED THE QUESTION MODULE. TYPE ANY QUESTION THAT
YOU LIKE TERMINATED BY A “?" FOLLOWED BY A SPACE.
PLEASE CONTINUE

>>> what causes decreased renal blood flow ?

THE MOST IMMEDIATE CAUSE OF DECREASED RENAL BLOOD FLOW IS DECREASED
PLASMA VOLUME AND DECREASED CARDIAC OUTPUT
PLEASE CONTINUE

>>> what is the usual result of decreased oncotic pressure ?
THE RESULT OF DECREASED ONCOTIC PRESSURE IS DIFFUSION OF WATER AND

SOLUTES TO INTERSTITIAL FLUIO
PLEASE CONTINUE

>>> what could cause decreased renal blood flow ?
THE MOST IMMEDIATE CAUSE OF DECREASED RENAL BLOOD FLOW IS DECREASED
PLASMA VOLUME AND DECREASED CARDIAC OUTPUT
PLEASE CONTINUE

>>> what could cause a decreased glomerular filtration rate ?

THE MOST IMMEDIATE CAUSE OF DECREASED GLOMERULAR FILTRATION RATE IS
DECREASED RENAL BLOOD FLOW OR DAMAGE TO GLOMERULI

>>> what is the possinle cause of hypoproteinamia ?

THE MOST IMMEDIATE CAUSE OF HYPOPROTEINEMIA IS MASSIVE PROTEINURIA

SURES ELSE SERS eecereEr ess ees esse eesscssacsssexeesszscessaesceercetcezans

FIGURE 1Ob. Explanations in inquiry mode
Privileged | G.A.Gorry Ga? Page 87

Methods of Procedura

Introduction

Much of the work reviewed above is already underway. Some activities
are more advanced than others, but alli the projects discussed are

receiving the attention of at least one member of our group. In most
cases, most of the members of the group are involved in at least some
aspect of each project. We expect that this mode of operation will be

common in the Laboratory, and as a result, it is not a simple matter to
give a detailed timetable for each project. The researchers in our
group will naturally tend to shift their attentions somewhat to those
problems which loom most prominantly at any point in time. We believe
that this flexibility will prove tremendously beneficial to the
Laboratory, but it, coupled with our present uncertainty about the

degree of difficulty each project will manifest, makes our current
projections only informed guesses.

Nonetheless, we offer here our best guesses as to the course the
research of the Laboratory will take. As our work proceeds, we will

undoubtedly modify these plans in the light of new problems and
developments.

Present Iliness Project

Because of its complexity, it is most difficult to chart the course of
the present illness project. The broad outlines are clear, but the
details are hard to discern at this point in time.

For the next six months or so, we will continue our detailed analysis
of the problem-solving behavior of a few renal experts. The procedure
we will use will include protocol analysis and close man-machine
interaction involving a computer simulation of cognitive process. This
approach has been quite successful so far, and we expect it will become
one of the major methodological tools of the Laboratory.

The work on the simulation program for the present illness will remain
focused on the presenting problem of edema during the next six months.
We believe that a very detailed study of the way in which one or two

experts deal with this one problem will prove extremely useful and
interesting.

Within a year, we will have a simulation of this behavior which is
rather complete, in that the program can take a a present illness for
edema which will deal with al! the major issues outlined in the above

discussion (e.g., pattern-matching of signs and symptoms, finding a
specific context for the problem, "backing up" in the face of failure,
etc.) in at least a preliminary way.

We cannot expect that the program will take a present illness of edema
which is fully comparabie {tc that which would be taken by an expert.
Privileged “Cla G.A.Gorry > | Page 88

The major problem, as we see things now, is not so much a matter of
strategy (although some knotty problems are apparent), but rather the
amount of real world knowledge which the expert uses. Thus the program
might do quite well on one problem, but on a second problem, it might
"fail" because it didn’t know that “waitresses who stand up all day
often get swollen ankles at night".

At this time (approximately July, 1975), we expect to produce a paper
aimed a a medical audience which discusses the cognitive theory we have
developed, and the implications of this theory with respect to such
issues as the assessment of problem solving skill, medical education,

etc. This paper will draw on the study of cognitive style which at this
point should have produced some. new and interesting results. (Of
course, this may be best presented in a separate paper.) The second
major paper will be focused on the use of computer science methadology

in cognitive theory formulation.

At this point, we expect that our experiences of the first six to
eight months will prompt us to undertake a re-design of the simulation
program, and will help us structure the “knowledge acquisition" problem
so that several teams can be set to work on it. During the year 197S-
1976, the emphasis should be on the broadening and deepening of the
knowledge base for the program. If large areas of knowledge can be

dealt with by separate groups, our work should proceed much more
rapidly.

Here we expect that the work on the formalization of clinical!

knowledge will begin to yield great benefits. By this time, a scheme
for codifying knowledge should be available, and a "compiler" for
knowledge expressed in this scheme will have been developed. This will

greatiy facilitate the expansion of the knowledge base of the simulation
program.

It should also aid in the exploration of another medical area. During
this year (1975-1976), we expect to begin a similar project ina

different medical speciality (perhaps cardiology). We would be
interested in assessing the usefulness of our theories and concepts ina
different area. Although we expect that some modifications will be
required, we believe the bulk of the theory will apply.

By July, 1976, we expect to have built sufficient knowledge about the
Present problems of edema, hematuria, etc. into the present illness
Program that its performance can be meaningfully compared with that of
clinicians of various skill levels. Such comparisons will involve

detailed studies of the protocols of the clinicians and the trace of the
program on the same cases.

Undoubtedly, this study will also point out deficiencies in theory and
in the program. The direction of this research beyond this point will
be determined in large part by the outcome of tests such as_ this. At
this point in time, we can say little other than that the basic effort
Privileged

 

G.A.Gorry a» : Page 89

Will be directed at expanding the theory and developing the program.

As we proceed, however, we will make a concerted effort to publicize
successes of the Laboratory and to find ways to make these successes
available to researchers in other centers. One way in which we will do
this is through publications; another Way may be through the ARPA
network. A third way is through conferences and research meetings. The
point is that our proposed work touches on so’many central issues that
it will be to our advantage and to the benefit of others for us to

maintain close contacts with the existing research community in computer
science and medicine.

Digitalis Advisor

It is anticipated that the central mathematica! algorithm will be
implemented and packaged in simple routines for limited physician use
within six months’ time. Programming of criteria for speed of

administration, interpretation of therapeutic and toxic effects and
searches for factors influencing sensitivity should take an additional
two to three months, with allowance for an additional two months to
create a crude set of programs to facilitate more extensive physician
interaction with the model. Thus, by April, 1975, we would hope to have
a crude program available for testing by physicians both in our
Laboratory and possibly in limited areas of the hospital. We would
envision this initial testing phase to encompass about three months
time, and then another three months for further program development
before a second stage program is available for testing. At that stage,
we would hope to be able to begin testing effectiveness among non-expert
physicians. We would plam that this trial include some of our surgical
colleagues, who deal with patients requiring this drug.

This test of effectiveness wil! require careful study of the decision-
making of clinicians and surgeons both before and after their
introduction to the program. This raises the question of how one should
measure the effectiveness of clinical decision-making, and we will have
to give this question careful thought. The particular problem we have
chosen, however, may make this problem somewhat less troublesome,
because over a sufficient number of trials, the toxic/therapeutic
response of the patient can be taken as the prime indicator of
effectiveness of decision-making.

Papers recounting the development of the program and the experience
With it in the clinical setting will be prepared at this time. Further,

steps will be taken to provide the program to other researchers for
their use and evaluation.

If this project is successful, we plan to initiate another “model-
based" effort such as the administration of antibiotic therapy or the
like to gain more experience, and to test our ability to transfer the
technology and understanding we have gained to other problems.
Privileged

 

C..Corry Page 98

GOBBLE Oevelopment

By introducing GOBBLE into the various projects which are underway,
we expect to learn a great deal about its limitations. Some are already
known to us, because we have made a conscious decision to defer the
development of certain features of the system until we have more
experience with medical problems. Others will arise in the course of
the research in the various projects. Thus at present, we can only give
a rough time-table for the development of the system.

The basic development of GOBBLE should be complete within the next
six months. Tnat is, by December 1, 1974, we should have the first
version in sufficiently de-bugged and polished state that it can be
“frozen” and it can be a major tool in the program development
activities of the Laboratory. The features of this first version of the
system will be: ,

1) An improved facility for stringing sub-contexts
together

2) Semantics for specifying retrieval searches through
various contexts and subcontexts

3) Facilities for specifying "a-kind-of" relationships
{e.g. pedal edema is a kind of edema) such that the
subclasses automatically take on the properties of the
main class unless otherwise indicated

4) A rudimentary capability for responding to
questions about the knowledge base

S) An improved dictionary facility to automatically
check new additions to the knowledge base for obvious
errors (misspellings, etc.) and obvious contradici tons

At this time, a small manual will be written on the use of the system,
and it will be formally introduced into each of the projects. For a

period of three months, we will record problems and failings in the
system. After this trial period, several decisions will be made.

First, we will decide whether GOBBLE is a viable and useful concept.
At present, we believe that it almost certainly will prove to be one.
It may prove more useful for some projects than for others, however, and

at this point, we will decide which projects should continue to use the
system.

From the recorded problems with the system and from our general

understanding of its limitations, we will identify the most important
additions to and revisions of the system which are required, and
undertake a new design. Into this design, we will incorporate the

results of the three projects described below, the specialists project,
the explanation and inquiry project, and the interface project. This
new implementation should be completed within a month or so, and then
GOBBLE will be a basic part of the work of the Laboratory, with
revisions being made as necessary by members of the staff.
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G.A.Gorry > Page 31

A detailed description of the system with examples of its
applications in the medical project will be issued by the Laboratory
about six months after the second implementation of the system.

In addition to further work on the time specialist, the development of

other specialists will be undertaken. The current choice for the next
project is the location specialist. This program will manage the common

sense knowledge about the parts of the body and their locations relative
to one another. This specialist wilt know the difference between the
inside and the outside of the body as well. In large, the location

specialist will be like the time specialist. Instead of a time-line for
organizing facts, the location specialist will maintain a model of the
body, and it will organize statements about locations around this model.

We expect that a first version of the location specialist can be
developed with eight months, and so by December, 1974, this specialist,
and the improved time specialist should be available in the second
version of GOBBLE. . Although other specialists will be developed, we

cannot say at this time how many there will be, or in what order they
Will be built. —

Further developments of GOBBLE or its descendants will flow from the

use of this technology in the medical projects. Their needs will
determine the efforts in this area.

Significance of the Research

The impediments to the use of computer science and technology to
favorably influence the quality and the quantity of health care
available to the community are large and complex. These impediments
will not fall to simple extensions of past work, rather new, more
powerful combinations of resources and people will be required. The
most immediate significance of the proposed laboratory is that it can
focus the attentions of first rate medical scientists and computer
scientists on one of the most important of these problems, the lack of a
Well-articulated theory of clinical cognition. Further the efforts of
these researchers can be built on the base of the most advanced
technology and methodology of its kind in existence.

The development of such a theory and the successful application
of the technology which will be developed in concert with the theory
Will radically alter the way in which expert physicians can interact
With programs, and the kind of expertise these programs can have.
Further the technology which results will allow an attack on many
clinical areas by other workers. Thus we see the techniques and
facilities which will result from our research as being the vital first
step on the road to creating distributable expertise in the form of
specialist consultant programs.
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In this way the physician dealing with even the most complex
problems in a site remote from consultants could be assured af guidance
that would allow him to enormously upgrade his performance. The
expectation is not that the local physician can perform at a level equal
to the best consultant but simply at a level approaching that of the
expert,.a level far above that generally achieved today.

Beyond the use of programs such -as these, and. perhaps even more
significant in the long run, lies the prospect of analogous programs
being prepared for the support of allied health personnel in the
delivery of primary medical care. Such support is vital, because even
if the current shortage of physicians can be overcame, it is unlikely

that the problem of maldistribution of physicians will be resolved. Feu
physicians wish to practice in the rural areas (consisting of nearly 48
million people without adequate access to physicians) nor in the inner
city where tens of millions more face a similar problem. For this
reason it seems to be highly likely that new classes of allied health
personnel must be trained to fulfill the primary care functions. Such

personnel must, if they are to be accepted by the patient, be able to
provide care of good quality. Current programs for use of allied health
Personnel, such as the MEQEX effort, promise quantity but cannot provide
quality and it is here that the computer can make its contribution.

Once the basic problems related to computer-support of the physician
have been worked out, as described in the present proposal, it should te
possible through utilization of this knowledge and experience to develop
programs geared to the needs of the allied health professional in his
triage function-making as certain as possible that he does not overlook
serious disease and restraining him from taking on complex problems
beyond his capability. These programs could also provide him with the
assistance necessary for dealing with crises under circumstances in
which a transfer of the patient is not feasible.

We realize, that most patients coming to most primary care physicians
(or or new kinds of allied health personnel envisioned as delivering
primary care) do not have serious diseases and that a wide range of
relatively simple algorithms wil! be necessary to assist in the care of
the patient. Nevertheless, these procedures must be organized within
the context of a knowledgable system in order to insure their correct
application. Qur studies and those being pursued at the Massachusetts
General and Beth Israel Hospitals and elsewhere should complement each
other . Thus in the long term we believe that our work can assist in
solving our manpower and quality problem by contributing to an
understanding of the use of the computer in serious management problems
by both physicians and non-physicians.

A second major benefit of this research is its potential impact
on medical education. The development of clearly understood theories of
expert knowledge and its application is a major goal of our effort.
Although it is undoubtedly true that effective decision-making is one of
the central factors in clinical practice, little, if any, attention is
Privi 'oc0d @igupialaaas, G.A.Gorry a> Page 93

directed to this subject in current medical education. Most medical
students are forced to infer from their observation and experience the
general principles of diagnostic and therapeutic decision-making. At
present there exist no well-articulated theories of medical decision-

making, and it is very difficult for the average medical student to
become a good problem-solver.

We believe that our work will result in extensive new knowledge of the
Way in which clinical experts solve problems, and further it will
suggest many new ways in which students can be introduced to the
processes upon which expertise is built. Rather than simply being a
collection of facts about the medical problem in question, programs wi! |
provide procedures for solving the problem, and students can study and

interact with these programs. Such procedures, supported by additional
reference material, organized in more associative ways, will allow the
student to enlarge his understanding of a given area.

A further benefit which will result from the activities of the
Laboratory will be the training of computer science graduate students to
work with clinicians on important research questions, and in turn the
Laboratory will offer clinicians the opportunity to learn about the
methodology of computer science. We believe that the Laboratory will be

the basis for a whole new area of coilaborative research and education,
an area which can greatiy benefit society.
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The Management of the Laboratory

As Principal Investigator and Director of the Laboratory, Professor

Gorry ultimately will be responsible for all activities of the
Laboratory, both scientific and administrative. Because of the
interdisciplinary nature of the activities of the Laboratory, Prafessor
Gorry will draw an the advice and. assistance of key senior people in

both medicine and computer science. Or. Schwartz has accepted the
responsibility for overseeing the medical aspects aspects of the

research, and he will be the Deputy Director of the Laboratory. His
judgments concerning. the medical. importance and relevance of projects
will be a key factor in determining the directions in which our efforts
go.

Professors Fredkin and.Minsky will help with the development = and

maintenance of close relations between the Laboratory and Project MAC
and the Artificial Intelligence Laboratory.

One of the goals of the Laboratory will be to promote a real
community devoted to research on computer science and clinical decision-
making. The facilities and research programs of the Laboratory

represent on nucleus. about which such a community could be centered.
Through a concerted effort to publicize these facilities and resources,
we will establish relationships with individuals. and groups who are
already active in this area or who could be fruitfully encouraged to
become active. A variety of relationships between the Laboratory and

these individuals and groups will be explored. We expect that some
relationships will be very close, while others will be quite loose.
We believe that it will be to the advantage of the research programs

of the Laboratory to develop such contacts, and in certain cases, to
grant the use of some of its resources to researchers who are
technically outside it. We would like to accept certain proposals from
research outside the Laboratory to use resources of the Laboratory,
particularly the computer. If such a proposal were in keeping with the
broad aims of the Laboratory, and if the required resources were
available, it would be accepted.

As an extension of the above idea, we would consider inviting certain
researchers to come to the Laboratory for a period of time ranging from
a few days to aie few months. These guests would be chosen for the
potential of the contribution they could make to the programs of . the
Laboratory. Such contributions might be tectures or consultations with
staff and students. These visitors would also provide a good source of

criticism of our activities, either from a medical or from a computer
science point of vieun.

Because we believe that informed criticism is very valuable, we pian
to form a small visiting committee composed of three or four respected
computer scientists and physicians from other institutions. They would
come to the Laboratory for a day or two every six months to review and
Privileged Gena C.A. Corry i Page 935

criticize our activities. We feel that careful consideration of our
work by this committee will be extremely valuable.

If it is possible, we would like to hold some form of conference once
each year on computer science and clinical decision-making at the
Laboratory. . Currently, we envision this as a working research
conference attended by people who are active in the field. We also will
encourage Laboratory staff to prepare papers for conferences and

publication as appropriate to help transfer the ideas and technology of
the Laboratory to others in the field.

Facilities

The Laboratory computer will be-directly linked to 4 large time-
sharing computer systems at M.I.T.: the MULTICS system which is ouned
by M.1.T. and operated by the Information Processing Center, and 3
compatible PDP-18 systems, 2 at Project MAC and ome at the Artificial

Intelligence Laboratory. Through this connection, we will have direct
access to an impressive array of software including an advanced
operating system and programming languages such as LISP. These
languages will operate on all these systems.

All these machines are linked to the ARPA network, and thus are
accessible to researchers and general users at 25 other locations. We

plan to connect our machine to this network as well to facilitate use of
our technology by selected researchers at other institutions.

In addition to these computers per se, we can draw on a large reservoir
of computer talent. The Laboratory will be located in the same building
with Project MAC and the Artificial Intelligence Laboratory, and many
members of these two research efforts have an active interest in our
work. Further, we expect to attract some very good graduate students in
computer science by virtue of our close proximity to these laboratories
and the inherent appeal of our research program.

Further, the Laboratory will have access to a library of computer
science publications, a printing and reproduction section, an

electronics shop, and a machine shop, all housed in the same building
with the Laboratory.

The primary offices of the clinical members of the effort will be
located at the New Engiand Medical Center Hospital. . The Hospital is a
general hospital consisting of about 488 beds. This private, non-profit
university hospital has 11,888 admissions per year and 148,888 out-
patient visits per year. Approximately 38% of these out-patient visits
are handied by the Department of Medicine. The in-patient Medical
Service is divided into units of 15 beds each, each of which has a
professional staff consisting of an attending physician, an assistant
resident, an intern, and two medical students. One or more of these
units will serve as a test environment for programs developed in the
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Laboratory.

As Physician-in-Chief, Dr. Schwartz has contro! of the beds in the
hospital. In addtion, Or. Kassirer is the Director of the House Staff
Training Program. Both these facts should greatiy facilitate the

interaction of the research program of the Laboratory with the clinical
environment.

Principal Investigator Assurance

The undersigned agrees to accept responsibility for the scientific and
technical conduct of the research project and for provision of required
progress reports if a grant. is awarded as the result of this
application.

 
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References

1) Schwartz, W.B., "Medicine and the Computer: The Promise and Problems
of Change", New England Journal of Medicine, 283: (December 3, 1978),
pp. 1257-1264

2) Newell, A., and Simon, H.A., Human Problem Solving, Prentice Hail,
Englewood Cliffs, N.J., 1972

3) Gorry, G.A. and Barnett, G.O0., "Sequential Diagnosis by Computer",
Journal of the American Medical Association, 285: (1968), pp. 849-854

4) Schwartz, W.B8., et al, “Decision Analysis and Clinical Judgment",
American Journal of Medicine, SS: (October, 1973), pp. 459-472

5) Gorry, G.A., "Decision Analysis as the Basis for Computer-Aided
Management of Acute Renal Failure", American Journal of Medicine, SS:
(October, 1973), pp. 473-484

6) Weed, L.L., Medical Records, Medical Education and Patient Care, Case
Western Reserve University Press, Cleveland, 1978

 

7) Slack, W.V., et al, “A Computer-Based Medical History System", New

»e
England Journal of Medicine, 274: (1966), pp.194-198

8) Bleich, H.L., “Computer Evaluation of Acid-Base Disorders", Journal
of Clinical Investigation, 48: (1969), pp. 1686-1696

3) Ginsburg, A.S., "Decision Analysis in Clinical Patient Management",
R-751-RC/nim, Rand Corporation, Santa Monica, 1978

18) Winograd, T., "A Procedural Model of Language Understanding", in

Schank, R.C. and Colby, K.M. (eds.) Computer Models of Thought and
Language, Freeman, San Francisco, 1973

11) Sussman, G.J. "A Computational Model of Skill Acquisition" M.I.T.
Ph.D. Thesis, 1973.

12) Minsky, M. and Papert, S., Progress Report of the M.I.T. Artificial
Intelligence Laboratory, January 1, 1972

13) Minsky, M. “Frame-Systems: A System for the Representation of
Knowledge”, unpublished paper, 1973.

14) Jelliffe, R.W., Buell, J., and Kalaba, R., "A Computer Program for
Digitalis Dosage Regimens" Math Biosci, (1978), pp. 179-193

15) Doherty, J, “Digitalis Glycosides: Pharmacokinetics and their
Clinical Implications", Ann Intern Med, (1972), pp. 891-986
Privi 99° @enaoaaas 6.A.Corry Page 98

16) Jelliffe, R.W., Buell, J., and Kalaba, R., “Reduction of Digitalis
Toxicity by Computer-assisted Glycoside Dosage Regimens", Ann Intern
Med, (1972), pp. 891-986

17) Peck C.C. and Sheiner L.B., "Computer-assisted Digoxin Therapy", New
England Journal of Medicine, (1973), pp. 441-446

18) Martin, W.A., "MAPL 2", Automatic Programming Group Memo., Project
MAC, 1973.

13) Sussman, G.J. and McDermott, 0.¥Y. “From PLANNER ta CONNIVER: A
Genetic Approach", Proceedings of the Fall Joint Computer Conference,
1972, pp. 1171-1179

28) Pratt, V., "A Linguistics Oriented Programming Language", Artificial
Intelligence Memo No. 277, Febuary 1973.