a cybernetic model for curriculum development

A CYBERNETIC MODEL FOR CURRICULUM DEVELOPMENTAuthor(s): DAVID PRATTSource: Instructional Science, Vol. 11, No. 1 (MAY 1982), pp. 1-12Published by: SpringerStable URL: http://www.jstor.org/stable/23368328 .

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Instructional Science 11 (1982) 1-12

Elsevier Scientific Publishing Company, Amsterdam — Printed in The Netherlands

A CYBERNETIC MODEL FOR CURRICULUM DEVELOPMENT

DAVID PRATT

Faculty of Education, Queen's University, Kingston, Canada K7L 3N6

ABSTRACT

The task of the curriculum developer is to design instructional systems which will

produce consistently high levels of learning despite wide variation in pupil characteristics.

This can be viewed as a cybernetic question of regulating variety in a system to produce stable and high level output. Six cybernetic principles — goal orientation, limitation of

input, monitoring, control decisions, restoration of equilibrium, and positive feedback —

are described, and their application to curriculum discussed. It is concluded that a cyber netic model can guide curriculum developers in designing effective learning systems.

Curriculum as an Applied Science

The last decade has seen enormous advances in curriculum development. The field is currently characterized by a sense of optimism and confidence which is the more striking when compared with the gloom and defeatism that prevailed in the "schools make no difference" aftermath of the Coleman

Report. It is only a decade since Schwab described the curriculum field as

moribund, and ascribed its moribundity to "inveterate, unexamined, and mistaken reliance on theory" (Schwab, 1969: 1). Schwab was half-right. The field of curriculum was not moribund: even as he wrote, the most

significant advance of a generation, Mastery Learning, was well under way. But the search for a "curriculum theory" was, as it remains, a false trail.

Curriculum, like such applied sciences as engineering or medicine, does not

generate theory of its own. Curriculum development is usually pragmatic, discovering by experience what works. Sometimes curriculum derives oper

ating principles from theory in the sciences; more commonly it first develops a practice and subsequently seeks its theoretical basis.

Curriculum development — the process of planning instructional

systems — has successfully adopted many operating principles from such

0020-4277/8 2/0000-0000/$ 2.75 © 1982 Elsevier Scientific Publishing Company



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fields as philosophy, measurement, and psychology. Cybernetics — which

might be defined as the science of self-regulation in systems — has enriched

many disciplines, from biology and ecology to political science and psychiatry. But although educators have adopted (somewhat loosely) such cybernetic terms as "feedback", the richness of cybernetics does not appear to have

been fully described or utilized in curriculum thought. Yet the central

concerns of curriculum developers — how to help all students learn, and how

to maximize individual growth — can be viewed as cybernetic questions. This paper will describe six basic principles from cybernetics which

have a direct application to curriculum development. They constitute a

model which helps to explain the success of certain curriculum practices, and

increases the capacity of practitioners to design effective curricula.

Cybernetic Systems

Before examining cybernetic principles, the basic cybernetic model

should be described, and one example provided of a cybernetic system.

Figure 1 illustrates the cybernetic model in its simplest form, in which there

is a control system and a controlled system. Control is defined as "any influence of one system on some other system which leads to the attainment

of some end state" (Landa, 1977: 8). Raw input enters the controlled

system, where it is transformed; the control system monitors the output,

intervening as necessary to maintain the desired level or quality. In an

instructional system, the desired output is student learning. This is monitored

by the instructor, who takes remedial action when underachievement becomes

evident. The model will apply even to self-instructional systems; indeed, it

is an important aim of education to develop in learners a capacity for self

conducted lifelong learning: in cybernetic terms, to have learners internalize

their own control system.

Fig. 1. Basic model of a cybernetic system.



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Cybernetic processes may be illustrated in more detail by examining an

example from human physiology. The human body contains numerous

cybernetic systems, such as the respiratory, cardiovascular, and endocrine

systems, all remarkable for their elegance and precision, which maintain the various body functions and constituents in equilibrium or homeostasis.

Temperature regulation is one such system. While it is extraordinarily elaborate and complex, its basic functioning is fairly well understood.

Human beings, like all animals, recognize a comfortable environmental

temperature, and seek to limit the variety in temperature input by avoiding extremes of heat and cold. The simplest response to temperature change is

behavioral: changing body location or position relative to sources of heat or

cold; physical movement; and use of all the artifacts of buildings, clothing, and heating and cooling devices. But in addition, people are equipped with an automatic regulative system for maintaining an internal temperature equilibrium.

The human body has various temperature sensors distributed in the skin and the body core. Information regarding heat and cold is transmitted to the

hypothalamus, a structure at the base of the brain, which is the main regulator of temperature as well as of many other body functions. The hypothalamus responds to neural feedback from the skin and other sensors, and to the

temperature of the blood flowing through the brain.

The hypothalamus functions as the switching mechanism to initiate certain reactions to temperature change. When body heat drops below a threshold level, the hypothalamus switches a number of mechanisms into

operation. Increased adrenalin is secreted into the bloodstream, metabolic

activity is accelerated, heart rate and blood pressure are increased, and

peripheral blood vessels are constricted. If these responses are insufficient, the skin papillae are erected (gooseflesh), and delay in feedback from the brain to the small muscles produces the symmetrical oscillation we know as

shivering. The cooling system reverses some of these processes. The thyroid gland

becomes less active, heart rate and blood pressure are decreased, blood vessels in the limbs and body surface dilate. If these defenses do not restore equili brium, sweat is secreted, cooling the skin as it evaporates. All the defenses come into play before blood temperature rises more than one degree. The

system functions primarily to protect the temperature of the brain, which is kept stable within one hundredth of a degree.

Figure 2 illustrates the human thermoregulation system. It is a classical

cybernetic system, which limits input from the environment, monitors the state of the system, compares it with a set point, triggers responses in the event of a discrepancy, and produces a stable output. The set point itself

may vary: temperature set point fluctuates on a 24-hour cycle, and (in women) also on a 28-day cycle, while in fever it is set slightly higher than normal.



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INPUT LIMITER ENVIRONMENT

Fig. 2. Cybernetic model of human thermoregulation.

The system is sufficiently responsive that fit and acclimatized subjects can

rest in an environmental temperature of 5°C, and perform heavy exercise in

which body heat product may reach 15 times the resting value, in environ

ments up to 50°C, without losing equilibrium of body temperature (Cabanac,

1972; Nielsen, 1970).

Curriculum Applications

Six basic principles are exemplified in cybernetic systems. Each of these

has a direct application to the design of curriculum.

1. GOAL ORIENTATION

Cybernetic systems are teleological, or goal-seeking. All such systems

have a set point, representing a goal or optimal state which they generate

themselves or are designed to follow. Without a set point, the system could

not recognize its own optimal state, and hence could not achieve it. Systems

involving voluntary human behavior are unique in that they are purposive:

the systems are conscious of the goals they pursue.

Extensive research over the past decade into the effect of specific goals

or expectations on human performance points clearly to the critical im

portance of a set point in human behavior. Hamner summarized a review of

the research with the conclusion that "the most immediate, direct, and



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motivational determinant of task performance is the subject's goal" (Hamner, 1974: 217). "Simply stated" an experimental study of goal-setting con

cluded, "when difficult (but attainable) goals are set for a person, he will

perform at a higher level than when goals are easier or are not clearly specified" (Dockstader et al., 1977: 1).

Aims, objectives, and performance criteria are the set point for a curriculum. They will contribute to system stability, that is, to consistent achievement by learners at the desired level, to the extent that they are the

focus of instruction, are explicit, and are accepted by all participants. The

quality of the curriculum goals will determine the quality of the curriculum

system. Principle 1: The quality and stability of a curriculum system will be a

function of the understanding and acceptance by all participants of the

expectations reflected in the goals.

2. LIMITATION OF INPUT

The complexity of a system's control mechanism is relative to the

variety or range of the system input. The more variety or disturbance per mitted to enter the system, the greater the energy that the system must

devote to managing that variety. All systems have boundaries or strategies for preventing, avoiding, or reducing input variety. Animals minimize the

effects of climatic change by migration, hibernation, construction of dens or

nests, and by their hide, feathers, fur, or body fat. The pupil of the eye contracts automatically to prevent the amount of light entering the visual

system and striking the retina from exceeding a danger limit. Churches are social systems which manage minor deviations from their doctrinal set point

(heresies), but exclude from membership those who reject basic doctrinal

premises (e.g., atheists). Such boundaries limit the amount of variety which

the internal regulative system must manage. The more variety excluded from

the system, the more stable the system. In most conventional instructional situations, the main kind of variety

excluded is that of age. The result is that classrooms are extremely homo

geneous in terms of age, although this factor has only slight and indirect

relevance for most learning. Some systems of "ability grouping" appear to

reduce variety primarily in terms of social class (Esposito, 1973). The kinds

of variety which are highly relevant to learning are cognitive prerequisites and motivation. If, for example, we can ensure that all our pupils have

mastered addition before we teach multiplication, and that they are all

interested or willing to learn multiplication, we can expect to produce the

desired learning output with little difficulty. Significant variety is normally allowed to enter instructional systems in the form of a wide range in reading

competence, which increases as students move through school (Goodlad and



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Anderson, 1963). This variety is too great to be managed effectively within the system, and the result is highly variable or unstable output.

A major task of the curriculum designer is to determine relevant and valid prerequisites for entry to a learning sequence. Such researchers as Bloom (1976) and Anderson (1976) have demonstrated the powerful effect on achievement that results from ensuring that all learners have acquired the

relevant cognitive prerequisites. Prerequisites are often discussed in the

ideological language of elitism and egalitarianism. But from a cybernetic perspective, a prerequisite is valid simply if it contributes to the stability of the instructional system. This implies exclusion or dissuasion of students from programs from which they could not benefit, either because they lack the minimum background to learn effectively, or because they have already mastered what is to be taught. Such exclusion, if without prejudice, and if

(in the case of underachievers) temporary and reversible by remediation, appears to conform to humane as well as to cybernetic principles.

Principle 2: Application of relevant prerequisites will increase the

stability of an instructional system.

3. MONITORING

All cybernetic systems have sensors which monitor the performance of the system. Sensors may operate continuously or intermittently. A car driver glances at the speedometer intermittently and accelerates or slows down to maintain a constant speed. The more frequently the driver checks the speedometer, the less correction will be necessary and the less the fluctuation in speed. On the other hand, the driver monitors direction almost

continuously, again making intermittent corrections as the car moves too close to the center or edge of the road. Such motor skills as walking or eye head movement are made possible by complex feedback systems with

receptors in the muscles, joints, tendons, and skin which constantly monitor and compute changes in load, mechanical advantage, position, and rates of

angular movement (Gibbs, 1970). Human sensing mechanisms can be im

proved by training and experience. Steel workers can distinguish several hundred shades of red where laymen can perceive only a few dozen; experi enced grinders can discern gaps of 0.6 microns, as compared with the be

ginner, who cannot see a gap below 10 microns (Pekelis, 1974). The effect of increased sensitivity is to provide faster and smoother control of output. In all systems, the more sensitive the sensors and the more frequently they operate, the more stable the system.

Most classroom teachers monitor pupil learning frequently and infor

mally, by observation of verbal and nonverbal responses, overview of written

work, dialog and consultation with individuals, and brief tests and quizzes. The principle underlying this formative evaluation is that the monitoring



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should be frequent and sensitive enough to indentify minor underachievement

before it develops into major failure. Assessing learning only once a semester

would not achieve this; on the other hand, formal daily assessment might consume inordinate amounts of instructional time. A consensus appears to be emerging among curriculum developers that the optimal length of an

instructional unit, that is, of a learning sequence containing specific objectives and formal evaluation, is about three weeks, ten hours of instruction, or the

time needed to teach as much material as can be adequately tested in twenty minutes (Bloom, 1976; Keller and Sherman, 1974). To guide the next set of

decisions, it is desirable that the outcome of such assessment be a diagnostic

profile of student achievement, rather than a unidimensional scale of success

or failure.

Principle 3: The stability of an instructional system will be a function

of the frequency and sensitivity of measurement of learning output.

4. CONTROL DECISIONS

Signals from the sensors are transmitted to a controller (or servo

mechanism, in cybernetic terms) which compares their value with the set

point. If there is a critical difference, that is, if the value is above or below

the predetermined thresholds, the controller signals remedial action. A

controller may function continuously, like the voltage regulator in a car, which has a variable response range, or, like the device in a buoy which

responds to a photoelectric cell, it may be an on/off switch with only two

possible values for the regulating variable. In both types, the faster the

controller responds, the less likely it is that fluctuation will disrupt the

system. In a military campaign, a general behind the lines (the controller)

compares information received from reconnaissance units (sensors) with

strategic objectives (set point), identifies the problem or discrepancy (system

error), and orders action on the part of infantry, artillery, etc. (effectors)

which will bring realization of the objectives closer. An indecisive general increases the delay between determining the problem and ordering the appro

priate response. A similar slowdown in response will occur if the decision

must be approved by a group of commanders. Hence MacAulay's observation

that, "Many an army has prospered under a bad commander, but no army

has every prospered under a debating society." In all cybernetic systems, the more rapid the response of the controller,

the more stable the system. As controller in the curriculum system, the

teacher makes decisions on the basis of feedback on learner achievement. A

fully articulated curriculum will provide guidelines for such decisions; for

example: "Administer remedial unit on photosynthesis to any student

scoring less than 80 per cent on the photosynthesis subtest." Such decisions

must be taken rapidly if system stability is to be restored and preserved.



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Tests which are time-consuming to mark are generally unsuitable for this

purpose. A major concern must always be to narrow the time between the

occurrence of underachievement and its measurement, detection, and

correction. It is hard to improve on the situation in which students complete

self-marking tests and know they can expect prompt remediation if they score below a recognized cut-off point.

Principle 4: A curriculum system will be stable to the extent that

decisions to remediate are made rapidly.

5. RESTORATION OF EQUILIBRIUM

The controller ascertains error and acts as a switching mechanism for

the effectors or actuators, which function to restore equilibrium. A nuclear

reactor provides a typical illustration. When a free neutron enters a uranium

235 nucleus, it causes it to fission, releasing 2 or 3 neutrons, which in turn

cause more nuclei to fission. To prevent the chain reaction from proceeding

exponentially, the surviving neutrons must be reduced to a factor of one. This is achieved by the insertion into the reactor core of rods of some such

neutron-absorbing material as boron. The boron rods and the driving mechanism which automatically pushes them in and out of the core constitute the control system which sustains the nuclear chain reaction in a steady state

(Mclntyre, 1975). Many natural systems contain a number of effectors, which are brought into operation in series to deal with threats to equilibrium. In the human body, the effectors for temperature regulation are the thyroid, adrenal, and sweat glands, the heart, the vasodilator and vasoconstrictor

centers, the arrector pili muscles, and the small muscles involved in shivering. The actuators "close the feedback loop", restoring equilibrium to the

system; the more rapid and effective their response, the more stable the

system. Remediation or correctives are the effectors used with learners whose

achievement falls below a predetermined threshold. If remediation is to restore stability to the instructional system, it must be sufficiently effective that it returns the underachieving student to the mainstream of the class, and it must be rapid enough that it has this effect before the other students have moved much further ahead. Reliance on individual tuition by the teacher, or on vague instructions to underachieving students to review past work are

likely to be both slow and ineffective. Prerecorded audio cassettes, structured

peer tutoring, random-access audiovisual materials, or print materials which are brief, specific, and motivational enough to be used in the pupil's own time are more likely to be appropriate. Such approaches imply prior design of remedial units. One of the more effective forms of remediation is to group students of varying aptitude together, and have them complete formative tests cooperatively; much informal peer tutoring will take place, enabling



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the functions of formative evaluation and remediation to be fulfilled simul

taneously. All of this assumes that underachievement will occur in a small

minority of students. Significant underachievement on the part of large numbers of students in a class suggests design defects which remedial proce dures alone may be unable to overcome.

Principle 5: A curriculum will produce stable learning to the extent

that remedial procedures are rapid and effective.

6. POSITIVE FEEDBACK

The feedback described so far is negative feedback, whereby comparison of output and set point generates an error signal; the error is cancelled by intervention of the effectors. This is the essence of self-regulation in homeo

static systems. But learning cannot be adequately conceptualized in terms of

negative feedback, equilibrium, or homeostasis; for the essence in learning is not stasis but growth.

In positive feedback, movement away from equilibrium is fed back into the system to produce further movement in the same direction. Positive feedback can be observed in the vicious circle of racial discrimination resulting in degradation which is used to justify further discrimination. The "knowl

edge explosion", the rate of cultural change, growth of bacteria, multi

plication of rabbits, crowd behavior, the emergence of a media "star", vendettas, wars, civil unrest and repression, love and hate, all manifest the

exponential growth typical of positive feedback. Positive feedback leads to one of two possible outcomes. One outcome

is catastrophe and collapse of the system. A nuclear explosion or a forest fire ends by destroying the system itself. Alternatively, positive feedback results in re-establishment of the set point at a different level. Inflation tends to

proceed exponentially, as the expectation of higher prices becomes built in to wage demands. In the Weimar Republic, it resulted in collapse of the

monetary system; but more commonly it eventually stabilizes at a new level.

Psychotic depression may end in the catastrophe of suicide, or the sufferer

may establish the classic equilibrium of withdrawal seen in institutionalized

depressives. Positive feedback has important manifestations in learning. The cycle of

failure — damaged self-image — lowered motivation — nonachievement of

critical learnings — accelerated failure, is well known to educators. Ultimately it leads either to the student dropping out of school mentally or physically, which eliminates the learning system, or to an equilibrium in which the

student exerts the minimum effort necessary to avoid major sanctions. The

success syndrome is a mirror image: successful achievement — raised self

image — increased motivation and time-on-task — acquisition of prerequisites —

increased probability of success.



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Observance of certain basic principles of curriculum development, such as high expectations, monitoring, and remediation, will help to ensure learner success which, as recent evidence shows, is cumulative overtime and repeated experience (Bloom, 1980). But the most striking examples of positive feed back in learning operate at a less scientific and more personal and creative level. These are the points at which a learner or a class will "take off' —

develop a sudden but unmistakable enthusiasm for a subject, or establish a

special relationship with a teacher. The effect is similar to that of an amplifier increasing the gain in an electronic system: the set point for output moves

rapidly to a higher threshold as learners and teacher develop and realize

higher expectations of each other and of themselves. These are the events which are most valued by teachers, and which have the most lasting effects on learners.

Principle 6: "The role of the teacher is not to extinguish fire, but to enkindle it" (Anton Ramonas).

The Cybernetic Model of Curriculum

Figure 3 illustrates the cybernetic model of curriculum. It is a model

which, when understood, makes immediate sense to most professional teachers, whose dual concern is to limit underachievement and maximize

Fig. 3. A cybernetic model of curriculum. Positive and negative signs denote positive and

negative feedback paths.



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learning. It is highly compatible with philosophical positions such as Rawls'

(1971) theory of justice which aim primarily to eliminate disadvantage; and

with Mastery Learning principles in which goals, prerequisites, formative

evaluation, and remediation play an important part. It is less compatible with laissez-faire or elitist approaches to schooling which tolerate high levels

of failure or seek to increase the variability in student achievement.

What has been described is not a set of metaphors or analogies, but laws

of cybernetics which apply universally to systems in the natural and the

contrived world. There is no reason to believe that education is an exception. This paper has attempted to show how cybernetic principles operate in

instructional systems, and hence how curriculum developers can utilize them

to increase their own effectiveness. While relatively recent approaches such

as Mastery Learning exemplify cybernetic principles, so do the age-old

practices used by a master potter training an apprentice, a Buddhist monk

instructing a disciple, and a mother teaching a nursery rhyme to a child.

Daniel Benor, the Israeli agricultural expert who has had great success

in teaching Third World farmers how to produce more food, comments that

"there are almost no new ideas, merely well-known principles applied

systematically" (Rowen, 1977). This appears to be the case with curriculum

development. And just as the world can no longer afford inefficient agricul

ture, society's tolerance is diminishing for schooling systems which operate at an amateur level of effectiveness. By providing a theoretical explanation for certain fundamental and familiar educational practices, cybernetics enhances our ability to develop curricula whose effectiveness is predictable.

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