In a few years, men will be able to communicate more effectively
through a machine than face to face.

That is a rather startling thing to say, but it is our conclusion. As
if in confirmation of it, we participated a few weeks ago in a
technical meeting held through a computer. In two days, the group
accomplished with the aid of a computer what normally might have taken
a week.

We shall talk more about the mechanics of the meeting later; it is
sufficient to note here that we were all in the same room. But for all
the communicating we did directly across that room, we could have been
thousands of miles apart and communicated just as effectively-as
people-over the distance.

Our emphasis on people is deliberate. A communications engineer thinks
of communicating as transferring information from one point to another
in codes and signals.

But to communicate is more than to send and to receive. Do two tape
recorders communicate when they play to each other and record from
each other? Not really - not in our sense. We believe that
communicators have to do something nontrivial with the information
they send and receive. And we believe that we are entering a
technological age in which we will be able to interact with the
richness of living information -- not merely in the passive way that
we have become accustomed to using books and libraries, but as active
participants in an ongoing process, bringing something to it through
our interaction with it, and not simply receiving something from it by
our connection to it.

To the people who telephone an airline flight operations information
service, the tape recorder that answers seems more than a passive
depository.  It is an often updated model of a changing situation -- a
synthesis of informa-tion collected, analyzed, evaluated, and
assembled to represent a situation or process in an organized way.

Still there is not much direct interaction with the airline
information service; the tape recording is not changed by the
customer's call. We want to emphasize something beyond its one-way
transfer: the increasing significance of the jointly constructive, the
mutually reinforcing aspect of communication -- the part that
transcends "now we both know a fact that only one of us knew before."
When minds interact, new ideas emerge. We want to talk about the
creative aspect of communication.

Creative, interactive communication requires a plastic or moldable
medium that can be modeled, a dynamic medium in which premises will
flow into consequences, and above all a common medium that can be
contributed to and experimented with by all.

Such a medium is at hand— the programmed digital computer. Its
presence can change the nature and value of communication even more
profoundly than did the printing press and the picture tube, for, as
we shall show, a well-programmed computer can provide direct access
both to informational resources and to the processes for making use of
the resources,

Communication: a comparison of models

To understand how and why the computer can have such an effect on
communication, we must examine the idea of modeling-in a computer and
with the aid of a computer. For modeling, we believe, is basic and
central to communication.  Any communication between people about the
same thing is a common revelatory experience about informational
models of that thing.  Each model is a conceptual structure of
abstractions formulated initially in the mind of one of the persons
who would communicate, and if the concepts in the mind of one would-be
communicator are very different from those in the mind of another,
there is no common model and no communication.

By far the most numerous, most sophisticated, and most important
models are those that reside in men's minds, In richness, plasticity,
facility, and economy, the mental model has no peer, but, in other
respects, it has shortcomings. It will not stand still for careful
study. It cannot be made to repeat a run. No one knows just how it
works. It serves its owner's hopes more faithfully than it serves
reason. It has access only to the information stored in one man's
head. It can be observed and manipulated only by one person.

Society rightly distrusts the modeling done by a single mind. Society
demands consensus, agreement, at least majority. Fundamentally, this
amounts to the requirement that individual models be compared and
brought into some degree of accord. The requirement is for
communication, which we now define concisely as "cooperative modeling"
-- cooperation in the construction, maintenance, and use of a model.

How can we be sure that we are modeling cooperatively, that we are
communicating, unless we can compare models?

When people communicate face to face, they externalize their models so
they can be sure they are talking about the same thing. Even such a
simple externalized model as a flow diagram or an outline-because it
can be seen by all the communicators -- serves as a focus for
discussion. It changes the nature of communication: When communicators
have no such common framework, they merely make speeches at each
other; but when they have a manipulable model before them, they utter
a few words, point, sketch, nod, or object.

The dynamics of such communication are so model-centered as to suggest
an important conclusion: Perhaps the reason present-day two-way
telecommunication falls so far short of face-to-face communication is
simply that it fails to provide facilities for externalizing models.
Is it really seeing the expression in the other's eye that makes the
face-to-face conference so much more productive than the telephone
conference call, or is it being able to create and modify external
models?

The project meeting as a model

In a technical project meeting, one can see going on, in fairly clear
relief, the modeling process that we contend constitutes
communication. Nearly every reader can recall a meeting held during
the formulative phase of a project. Each member of the project brings
to such a meeting a somewhat different mental model of the common
undertaking— its purposes, its goals, its plans, its progress, and its
status. Each of these models interrelates the past, present, and
future states of affairs of (1) himself; (2) the group he represents;
(3) his boss; (4) the project.

Many of the primary data the participants bring to the meeting are in
undigested and uncorrelated form. To each participant, his own
collections of data are interesting and important in and of
themselves. And they are more than files of facts and recurring
reports. They are strongly influenced by insight, subjective feelings,
and educated guesses. Thus, each individual's data are reflected in
his mental model. Getting his colleagues to incorporate his data into
their models is the essence of the communications task.

Suppose you could see the models in the minds of two would-be
communicators at this meeting. You could tell, by observing their
models, whether or not communication was taking place. If, at the
outset, their two models were similar in structure but different
simply in the values of certain parameters, then communication would
cause convergence toward a common pattern. That is the easiest and
most frequent kind of communication.


[Caption: When mental models are dissimilar, the achievement of
communication might be signaled by changes in the structure of one of
the models, or both of them.]


If the two mental models were structurally dissimilar, then the
achievement of communication would be signaled by structural changes
in one of the models or in both of them. We might conclude that one of
the communicating parties was having insights or trying out new
hypotheses in order to begin to understand the other -- or that both
were restructuring their mental models to achieve commonality.

The meeting of many interacting minds is a more complicated process.  
Suggestions and recommendations may be elicited from all sides. The
interplay may produce, not just a solution to a problem, but a new set
of rules for solving problems. That, of course, is the essence of
creative interaction. The process of maintaining a current model has
within it a set of changing or changeable rules for the processing or
disposition of information.

The project meeting we have just described is representative of a
broad class of human endeavor which may be described as informational
housekeeping. The latter is what computers today are used for in the
main; they process payroll checks, keep track of bank balances,
calculate orbits of space vehicles, control repetitive machine
processes, and maintain varieties of debit and credit lists. Mostly
they have not been used to make coherent pictures of not well
understood situations.

We referred earlier to a meeting in which the participants interacted
with each other through a computer. That meeting was organized by Doug
Engelbart of Stanford Research Institute and was actually a
progress-review conference for a specific project. The subject under
discussion was rich in detail and broad enough in scope that no one of
the attendees, not even the host, could know all the information
pertaining to this particular project.

Face to face through a computer

Tables were arranged to form a square work area with five on a side.
The center of the area contained six television monitors which
displayed the alphanumeric output of a computer located elsewhere in
the building but remotely controlled from a keyboard and a set of
electronic pointer controllers called "mice." Any participantin the
meeting could move a near-by mouse, and thus control the movements of
a tracking pointer on the TV screen for all other participants to see.

Each person working on the project had prepared a topical outline of
his particular presentation for the meeting, and his outline appeared
on the screens as he talked— providing a broad view of his own model.
Many of the outline statements contained the names of particular
reference files which the speaker could recall from the computer to
appear in detail on the screens, for, from the beginning of the
project, its participants had put their work into the computer
system's files.

So the meeting began much like any other meeting in the sense that
there was an overall list of agenda and that each speaker had brought
with him (figuratively in his briefcase but really within the
computer) the material he would be talking about.

The computer system was a significant aid in exploring the depth and
breadth of the material. More detailed information could be displayed
when facts had to be pinpointed; more global information could be
displayed to answer questions of relevance and interrelationship. A
future version of this system will make it possible for each
participant, on his own TV screen, to thumb through the speaker's
files as the speaker talks— and thus check out incidental questions
without interrupting the presentation for substantiation.


[Caption: At a project meeting held through a computer, you can thumb
through the speaker's primary data without interrupting him to
substantiate or explain.]


[Caption: A communication system should make a positive contribution
to the discovery and arousal of interests.]


Obviously, collections of primary data can get too large to digest.
There comes a time when the complexity of a communications process
exceeds the available resources and the capability to cope with it;
and at that point one has to simplify and draw conclusions.

It is frightening to realize how early and drastically one does
simplify, how prematurely one does conclude, even when the stakes are
high and when the transmission facilities and information resources
are extraordinary.  Deep modeling to communicate -- to understand --
requires a huge investment.  Perhaps even governments cannot afford it
yet.

But someday governments may not be able not to afford it. For, while
we have been talking about the communicant ion process as a
cooperative modeling effort in a mutual environment, there is also an
aspect of communication with or about an uncooperative opponent. As
nearly as we can judge from reports of recent international crises,
out of the hundreds of alternatives that confronted the decision
makers at each decision point or ply in the "game," on the average
only a few, and never more than a few dozen could be considered, and
only a few branches of the game could be explored deeper than two or
three such plies before action had to be taken. Each side was busy
trying to model what the other side might be up to-but modeling takes
time, and the pressure of events forces simplification even when it is
dangerous.

Whether we attempt to communicate across a division of interests, or
whether we engage in a cooperative effort, it is clear that we need to
be able to model faster and to greater depth. The importance of
improving decision-making processes -- not only in government, but
throughout business and the professions -- is so great as to warrant
every effort.

The computer -- switch or interactor? 

As we see it, group decision-making is simply the active, executive,
effect-producing aspect of the kind of communication we are
discussing. We have commented that one must oversimplify. We have
tried to say why one must oversimplify. But we should not oversimplify
the main point of this article.  We can say with genuine and strong
conviction that a particular form of digital computer organization,
with its programs and its data, constitutes the dynamic, moldable
medium that can revolutionize the art of modeling and that in so doing
can improve the effectiveness of communication among people so much as
perhaps to revolutionize that also.

But we must associate with that statement at once the qualification
that the computer alone can make no contribution that will help us,
and that the computer with the programs and the data that it has today
can do little more than suggest a direction and provide a few germinal
examples.  Emphatically we do not say: "Buy a computer and your
communication problems will be solved."

What we do say is that we, together with many colleagues who have had
the experience of working on-line and interactively with computers,
have already sensed more responsiveness and facilitation and "power"
than we had hoped for, considering the inappropriateness of present
machines and the primitiveness of their software. Many of us are
therefore confident (some of us to the point of religious zeal) that
truly significant achievements, which will markedly improve our
effectiveness in communication, now are on the horizon.

Many communications engineers, too, are presently excited about the
application of digital computers to communication. However, the
function they want computers to implement is the switching function.
Computers will either switch the communication lines, connecting them
together in required configurations, or switch (the technical term is
"store and forward") messages.  

The switching function is important but it is not the one we have in
mind when we say that the computer can revolutionize communication. We
are stressing the modeling function, not the switching function. Until
now, the communications engineer has not felt it within his province
to facilitate the modeling function, to make an interactive,
cooperative modeling facility.  Information transmission and
information processing have always been carried out separately and
have become separately institutionalized. There are strong
intellectual and social benefits to be realized by the melding of
these two technologies. There are also, however, powerful legal and
administrative obstacles in the way of any such melding.

Distributed intellectual resources 

We have seen the beginnings of communication through a computer --
communication among people at consoles located in the same room or on
the same university campus or even at distantly separated laboratories
of the same research and development organization. This kind of
communication -- through a single multiaccess computer with the aid of
telephone lines -- is beginning to foster cooperation and promote
coherence more effectively than do present arrangements for sharing
computer programs by exchanging magnetic tapes by messenger or mail.
Computer programs are very important because they transcend mere
"data''— they include procedures and processes for structuring and
manipulating data. These are the main resources we can now concentrate
and share with the aid of the tools and techniques of computers and
communication, but they are only a part of the whole that we can learn
to concentrate and share. The whole includes raw data, digested data,
data about the location of data -- and documents -- and most
especially models.

To appreciate the import ante the new computer-aided communication can
have, one must consider the dynamics of "critical mass," as it applies
to cooperation in creative endeavor. Take any problem worthy of the
name, and you find only a few people who can contribute effectively to
its solution.  Those people must be brought into close intellectual
partnership so that their ideas can come into contact with one
another. But bring these people together physically in one place to
form a team, and you have trouble, for the most creative people are
often not the best team players, and there are not enough top
positions in a single organization to keep them all happy.  Let them
go their separate ways, and each creates his own empire, large or
small, and devotes more time to the role of emperor than to the role
of problem solver. The principals still get together at meetings. They
still visit one another. But the time scale of their communication
stretches out, and the correlations among mental models degenerate
between meetings so that it may take a year to do a week's
communicating. There has to be some way of facilitating communicant
ion among people wit bout bringing them together in one place.

A single multiaccess computer would fill the bill if expense were no
object, but there is no way, with a single computer and individual
communication lines to several geographically separated consoles, to
avoid paying an unwarrantedly large bill for transmission. Part of the
economic difficulty lies in our present communications system. When a
computer is used interactively from a typewriter console, the signals
transmitted between the console and the computer are intermittent and
not very frequent. They do not require continuous access to a
telephone channel; a good part of the time they do not even require
the full information rate of such a channel.  The difficulty is that
the common carriers do not provide the kind of service one would like
to have---a service that would let one have ad lib access to a channel
for short intervals and not be charged when one is not using the
channel.

It seems likely that a store-and-forward (i. e., store-for-just-a-
moment-and-forward-right-away) message service would be best for this
purpose, whereas the common carriers offer, instead, service that sets
up a channel for one's individual use for a period not shorter than
one minute.

The problem is further complicated because interaction with a computer
via a fast and flexible graphic display, which is for most purposes
far superior to interaction through a slow-printing typewriter,
requires markedly higher information rates. Not necessarily more
information, but the same amount in faster bursts -- more difficult to
handle efficiently with the conventional common-carrier facilities.

It is perhaps not surprising that there are incompatibilities between
the requirements of computer systems and the services supplied by the
common carriers, for most of the common-carrier services were
developed in support of voice rather than digital communication.
Nevertheless, the incompatibilities are frustrating. It appears that
the best and quickest way to overcome them— and to move forward the
development of interactive communities of geographically separated
people— is to set up an experimental network of multiaccess computers.
Computers would concentrate and interleave the concurrent,
intermittent messages of many users and their programs so as to
utilize wide-band transmission channels continuously and efficiently,
with marked reduction in overall cost.

Computer and information networks 

The concept of computers connected to computers is not new. Computer
manufacturers have successfully installed and maintained
interconnected computers for some years now. But the computers in most
instances are from families of machines compatible in both software
and hardware, and they are in the same location. More important, the
interconnected computers are not interactive, general-purpose,
multiaccess machines of the type described by David [1] and Licklider
[2]. Although more interactive multi-access computer systems are being
delivered now, and although more groups plan to be using these systems
within the next year, there are at present perhaps only as few as half
a dozen interactive multiaccess computer communities.

These communities are socio-technical pioneers, in several ways out
ahead of the rest of the computer world: What makes them so? First,
some of their members are computer scientists and engineers who
understand the concept of man-computer interaction and the technology
of interactive multiaccess systems. Second, others of their members
are creative people in other fields and disciplines who recognize the
usefulness and who sense the impact of interactive multiaccess
computing upon their work. Third, the communities have large
multiaccess computers and have learned to use them. And, fourth, their
efforts are regenerative.

In the half-dozen communities, the computer systems research and
development and the development of substantive applications mutually
support each other. They are producing large and growing resources of
programs, data, and know-how. But we have seen only the beginning.
There is much more programming and data collection -- and much more
learning how to cooperate-to be done before the full potential of the
concept can be realized.

Obviously, multiaccess systems must be developed interactively. The
systems being built must remain flexible and open-ended throughout the
process of development, which is evolutionary.

Such systems cannot be developed in small ways on small machines.  
They require large, multiaccess computers, which are necessarily
complex.  Indeed, the sonic barrier in the development of such systems
is complexity.

These new computer systems we are describing differ from other
computer systems advertised with the same labels: interactive,
time-sharing, multiaccess. They differ by having a greater degree of
open-endedness, by rendering more services, and above all by providing
facilities that foster a working sense of community among their users.
The commercially available time-sharing services do not yet offer the
power and flexibility of soft ware resources— the "general
purposeness''— of the interactive multiaccess systems of the System
Development Corporation in Santa Monica, the University of California
at Berkeley, Massachusetts Institute of Technology in Cambridge and
Lexington, Mass. -- which have been collectively serving about a
thousand people for several years.

The thousand people include many of the leaders of the ongoing
revolution in the computer world. For over a year they have been
preparing for the transition to a radically new organization of
hardware and software, designed to support many more simultaneous
users than the current systems, and to offer them -- through new
languages, new file-handling systems, and new graphic displays -- the
fast, smooth interaction required for truly effective man-computer
partnership.

Experience has shown the importance of making the response time short
and the conversation free and easy. We think those attributes will be
almost as important for a network of computers as for a single
computer.

Today the on-line communities are separated from one another
functionally as well as geographically. Each member can look only to
the processing, storage and software capability of the facility upon
which his community is centered. But now the move is on to
interconnect the separate communities and thereby transform them into,
let us call it, a supercommunity. The hope is that interconnection
will make available to all the members of all the communities the
programs and data resources of the entire supercommunity.  First, let
us indicate how these communities can be interconnected; then we shall
describe one hypothetical person's interaction with this network, of
interconnected computers.

Message processing 

The hardware of a multiaccess computer system includes one or more
central processors, several kinds of memory -- core, disks, drums, and
tapes -- and many consoles for the simultaneous on-line users.
Different users can work simultaneously on diverse tasks. The software
of such a system includes supervisory programs (which control the
whole operation), system programs for interpretation of the user's
commands, the handling of his files, and graphical or alphanumeric
display of information to him (which permit people not skilled in the
machine's language to use the system effectively), and programs and
data created by the users themselves. The collection of people,
hardware, and software-the multiaccess computer together with its
local community of users -- will become a node in a geographically
distributed computer network. Let us assume for a moment that such a
network has been formed.

For each node there is a small, general-purpose computer which we
shall call a "message processor." The message processors of all the
nodes are interconnected to form a fast store-and-forward network. The
large multi-access computer at each node is connected directly to the
message processor there. Through the network of message processors,
therefore, all the large computers can communicate with one another.
And through them, all the members of the supercommunity can
communicate-with other people, with programs, with data, or with
selected combinations of those resources. The message processors,
being all alike, introduce an element of uniformity into an otherwise
grossly nonuniform situation, for they facilitate both hardware and
software compatibility among diverse and poorly compatible computers.  
The links among the message processors are transmission and high-speed
digital switching facilities provided by common carrier. This allows
the linking of the message processors to be reconfigured in response
to demand.

A message can be thought of as a short sequence of "bits" flowing
through the network from one multiaccess computer to another. It
consists of two types of information: control and data. Control
information guides the transmission of data from source to
destination. In present transmission systems, errors are too frequent
for many computer applications. However, through the use of error
detection and correction or retransmission procedures in the message
processors, messages can be delivered to their destinations intact
even though many of their "bits" were mutilated at one point or
another along the way. In short, the message processors function in
the system as traffic directors, controllers, and correctors.

Today, programs created at one installation on a given manufacturer's
computer are generally not of much value to users of a different
manufacturer's computer at another installation. After learning (with
difficulty) of a distant program's existence, one has to get it,
understand it, and recode it for his own computer. The cost is
comparable to the cost of preparing a new program from scratch, which
is, in fact, what most programmers usually do. On a national scale,
the annual cost is enormous. Within a network of interactive,
multiaccess computer systems, on the other hand, a person at one node
will have access to programs running at other nodes, even though those
programs were written in different languages for different computers.

The feasibility of using programs at remote locations has been shown
by the successful linking of the AN/ FSQ-32 computer at Systems
Development Corporation in Santa Monica, Calif., with the TX-2
computer across the continent at the Lincoln Laboratory in Lexington,
Mass. A person at a TX-2 graphic console can make use of a unique
list-processing program at SDC, which would be prohibitively expensive
to translate for use on the TX-2. A network of 14 such diverse
computers, all of which will be capable of sharing one another's
resources, is now being planned by the Defense Department's Advanced
Research Projects Agency, and its contractors.

The system's way of managing data is crucial to the user who works in
interaction with many other people. It should put generally useful
data, if not subject to control of access, into public files. Each
user, however, should have complete control over his personal files.
He should define and distribute the "keys" to each such file,
exercising his option to exclude all others from any kind of access to
it; or to permit anyone to "read" but not modify or execute it; or to
permit selected individuals or groups to execute but not read it; and
so on— with as much detailed specification or as much aggregation as
he likes. The system should provide for group and organizational files
within its overall information base.


[Caption: Interactive communication consists of short spurts of dialog
. . . . . ]


At least one of the new multiaccess systems will exhibit such features. 
In several of the research centers we have mentioned, security and privacy 
of information are subjects of active concern; they are beginning to get the 
attention they deserve. 

In a multiaccess system, the number of consoles permitted to use the
computer simultaneously depends upon the load placed on the computer
by the users' jobs, and may be varied automatically as the load
changes.  Large general-purpose multiaccess systems operating today
can typically support 20 to 30 simultaneous users. Some of these users
may work with low-level "assembly" languages while others use
higher-level "compiler" or "interpreter" languages. Concurrently,
others may use data management and graphical systems. And so on.

But back to our hypothetical user. He seats himself at his console,
which may be a terminal keyboard plus a relatively slow printer, a
sophisticated graphical console, or any one of several intermediate
devices. He dials his local computer and "logs in" by presenting his
name, problem number, and password to the monitor program. He calls
for either a public program, one of his own programs, or a colleague's
program that he has permission to use.  The monitor links him to it,
and he then communicates with that program.


[Caption: . . . filibustering destroys communication.] 


When the user (or the program) needs service from a program at another
node in the network, he (or it) requests the service by specifying the
location of the appropriate computer and the identity of the program
required. If necessary, he uses computerized directories to determine
those data. The request is translated by one or more of the message
processors into the precise language required by the remote computer's
monitor. Now the user (or his local program) and the remote program
can interchange information.  When the information transfer is
complete, the user (or his local program)  dismisses the remote
computer, again with the aid of the message processors.  In a
commercial system, the remote processor would at this point record
cost information for use in billing.

Who can afford it? 

The mention of billing brings up an important matter. Computers and
long-distance calls have "expensive" images. One of the standard
reactions to the idea of "on-line communities" is: "It sounds great,
but who can afford it ?"

In considering that question, let us do a little arithmetic. The main
elements of the cost of computer-facilitated communication, over and
above the salaries of the communicators, are the cost storage,
transmission, and supporting software. of the consoles, processing, In
each category, there is a wide range of possible costs, depending in
part upon the sophistication of the equipment, programs, or services
employed and in part upon whether they are custom-made or
mass-produced.

Making rough estimates of the hourly component costs per user, we
arrived at the following: $1 for a console, $5 for one man's share of
the services of a processor, 70 cents for storage, $3 for transmission
via line leased from a common carrier, and $1 for software support— a
total cost of just less than $11 per communicator hour.

The only obviously untenable assumption underlying that result, we
believe, is the assumption that one's console and the personal files
would be used 160 hours per month. All the other items are assumed to
be shared with others, and experience indicates that time-sharing
leads on the average to somewhat greater utilization than the 160
hours per month that we assumed, Note, however, that the console and
the personal files are items used also in individual problem solving
and decision making. Surely those activities, taken together with
communication, would occupy at least 25% of the working hours of the
on-line executive, scientist or engineer. If we cut the duty factor of
the console and files to one quarter of 160 hours per month, the
estimated total cost comes to $16 per hour.

Let us assume that our $16/ hr interactive computer link is set up
between Boston, Mass., and Washington, D. C. Is $16/ hr affordable?
Compare it first with the cost of ordinary telephone communication:
Even if you take advantage of the lower charge per minute for long
calls, it is less than the daytime direct-dial station-to-station
toll. Compare it with the cost of travel: If one flies from Boston to
Washington in the morning and back in the evening, he can have eight
working hours in the capital city in return for about $64 in air and
taxi fares plus the spending of four of his early morning and evening
hours en route. If those four hours are worth $16 each, then the bill
for the eight hours in Washington is $128— again $16 per hour. Or look
at it still another way: If computer-aided communication doubled the
effectiveness of a man paid $16 per hour then, according to our
estimate, it would be worth what it cost if it could be bought right
now. Thus we have some basis for arguing that computer-aided
communication is economically feasible. But we must admit that the
figure of $16 per hour sounds high, and we do not want to let our
discussion depend upon it.

Fortunately, we do not have to, for the system we envision cannot be
bought at this moment. The time scale provides a basis for genuine
optimism about the cost picture. It will take two years, at least, to
bring the first interactive computer networks up to a significant
level of experimental activity. Operational systems might reach
critical size in as little as six years if everyone got onto the
bandwagon, but there is little point in making cost estimates for a
nearer date. So let us take six years as the target.

In the computer field, the cost of a unit of processing and the cost
of a unit of storage have been dropping for two decades at the rate of
50% or more every two years. In six years, there is time for at least
three such drops, which cut a dollar down to 12 1/ 2 cents. Three
halvings would take the cost of processing, now $5 per hour on our
assumptions, down to less than 65 cents per hour.

Such advances in capability, accompanied by reduction in cost, lead us
to expect that computer facilitation will be affordable before many
people are ready to take advantage of it. The only areas that cause us
concern are consoles and transmission.

In the console field, there is plenty of competition; many firms have
entered the console sweepstakes, and more are entering every month.
Lack of competition is not the problem. The problem is the problem of
the chicken and the egg— in the factory and in the market. If a few
companies would take the plunge into mass manufacture, then the cost
of a satisfactory console would drop enough to open up a mass market.
If large on-line communities were already in being, their mass market
would attract mass manufacture. But at present there is neither mass
manufacture nor a mass market, and consequently there is no low-cost
console suitable for interactive on-line communication.

In the field of transmission, the difficulty may be lack of
competition.  At any rate, the cost of transmission is not falling
nearly as fast as the cost of processing and storage. Nor is it
falling nearly as fast as we think it should fall. Even the advent of
satellites has affected the cost picture by less than a factor of two.
That fact does not cause immediate distress because (unless the
distance is very great) transmission cost is not now the dominant
cost. But, at the rate things are going, in six years it will be the
dominant cost. That prospect concerns us greatly and is the strongest
damper to our hopes for near-term realization of operationally
significant interactive networks and significant on-line communities.

On-line interactive communities 

But let us be optimistic. What will on-line interactive communities be
like?  In most fields they will consist of geographically separated
members, sometimes grouped in small clusters and sometimes working
individually. They will be communities not of common location, but of
common interest. In each field, the overall community of interest will
be large enough to support a comprehensive system of field-oriented
programs and data.

In each geographical sector, the total number of users -- summed over
all the fields of interest -- will be large enough to support
extensive general-purpose information processing and storage
facilities. All of these will be interconnected by telecommunications
channels. The whole will constitute a labile network of networks --
ever-changing in both content and configuration.

What will go on inside? Eventually, every informational transaction of
sufficient consequence to warrant the cost. Each secretary's
typewriter, each data-gathering instrument, conceivably each dictation
microphone, will feed into the network.

You will not send a letter or a telegram; you will simply identify the
people whose files should be linked to yours and the parts to which
they should be linked-and perhaps specify a coefficient of urgency.
You will seldom make a telephone call; you will ask the network to
link your consoles together,

You will seldom make a purely business trip, because linking consoles
will be so much more efficient. When you do visit another person with
the object of intellectual communication, you and he will sit at a
two-place console and interact as much through it as face to face. If
our extrapolation from Doug Engelbart's meeting proves correct, you
will spend much more time in computer-facilitated teleconferences and
much less en route to meetings.

A very important part of each man's interaction with his on-line
community will be mediated by his OLIVER. The acronym OLIVER honors
Oliver Selfridge, originator of the concept. An OLIVER is, or will be
when there is one, an "on-line interactive vicarious expediter and
responder," a complex of computer programs and data that resides
within the network and acts on behalf of its principal, taking care of
many minor matters that do not require his personal attention and
buffering him from the demanding world.  "You are describing a
secretary," you will say. But no! Secretaries will have OLIVERS.


[Caption: Your computer will know who is prestigious in your eyes and 
buffer you from a demanding world.] 


At your command, your OLIVER will take notes (or refrain from taking
notes) on what you do, what you read, what you buy and where you buy
it.  It will know who your friends are, your mere acquaintances. It
will know your value structure, who is prestigious in your eyes, for
whom you will do what with what priority, and who can have access to
which of your personal files.  It will know your organization's rules
pertaining to proprietary information and the government's rules
relating to security classification.

Some parts of your OLIVER program will be common with parts of other
people's OLIVERS; other parts will be custom-made for you, or by you,
or will have developed idiosyncrasies through "learning" based on its
experience in your service.

Available within the network will be functions and services to which you 
In the former group will be investment guidance, tax counseling, selective 
dissemination of information in your field of specialization, announcement of 
cultural, sport, and entertainment events that fit your interests, etc. In the 
latter group will be dictionaries, encyclopedias, indexes, catalogues, editing 
programs, teaching programs, testing programs, programming systems, 
data bases, and -- most important -- communication, display, and modeling 
programs. 

All these will be -- at some late date in the history of networking --
systematized and coherent; you will be able to get along in one basic
language up to the point at which you choose a specialized language
for its power or terseness.

When people do their informational work "at the console" and "through
the network," telecommunication will be as natural an extension of
individual work as face-to-face communication is now. The impact of
that fact, and of the marked facilitation of the communicative
process, will be very great— both on the individual and on society.

First, life will be happier for the on-line individual because the people 
with whom one interacts most strongly will be selected more by commonality 
of interests and goals than by accidents of proximity. Second, communication 
will be more effective and productive, and therefore more enjoyable. 
Third, much communication and interaction will be with programs and programmed 
models, which will be (a) highly responsive, (b) supplementary to 
one's own capabilities, rather than competitive, and (c) capable of representing 
progressively more complex ideas without necessarily displaying all 
the levels of their structure at the same time-and which will therefore be 
both challenging and rewarding. And, fourth, there will be plenty of opportunity 
for everyone (who can afford a console) to find his calling, for the 
to him— with programs ready to guide him or to help him explore. 

For the society, the impact will be good or bad, depending mainly on
the question: Will "to be on line" be a privilege or a right? If only
a favored segment of the population gets a chance to enjoy the
advantage of "intelligence amplification," the network may exaggerate
the discontinuity in the spectrum of intellectual opportunity.

On the other hand, if the network idea should prove to do for
education what a few have envisioned in hope, if not in concrete
detailed plan, and if all minds should prove to be responsive, surely
the boon to humankind would be beyond measure.

Unemployment would disappear from the face of the earth forever, for
consider the magnitude of the task of adapting the network's software
to all the new generations of computer, coming closer and closer upon
the heels of their predecessors until the entire population of the
world is caught up in an infinite crescendo of on-line interactive
debugging.
--------------

Acknowledgements 

Evan Herbert edited the article and acted as intermediary during its
writing between Licklider in Boston and Taylor in Washington.  Roland
B. Wilson drew the cartoons to accompany the original article.


References 

[1] Edward E. David, Jr., "Sharing a Computer," International Science
and Technology, June, 1966.


[2] J. C. R. Licklider, "Man-Computer Partnership," International
Science and Technology, May, 1965.

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*Copyright Science and Society, April 1968.
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