Instructional Science 11 (1982) 1-12 Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands

A CYBERNETIC MODEL F O R CURRICULUM DEVELOPMENT

DAVID PRATT Faculty o f 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 t h a t 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, mad ascribed its moribundi ty to "inveterate, unexamined, and mistaken reliance on theory" (Schwab, 1969: 1). Schwab was half-right. The field o f 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

0020-4277/82/0000-0000/$2.75 © 1982 Elsevier Scientific Publishing Company

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 o f 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 o f 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 cybemet ic 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 ou tpu t 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.

INPUT

CONTROL

SYSTEM

Feedback

loop

~] CONTROLLED q SYST M ] OUTPUT

Fig. 1. Basic model of a cybernetic system.

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 consti tuents 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 he, at 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 o f 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 o f temperature as well as o f many other body functions. The hypothalamus responds to neural feedback from the skin and other sensors, and to the temperature o f 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 o f 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 LIMI TER

houses

INPUT

heat from 1~ environment, exercise, and body

SENSORS l I thermal receptors , in body

SET POINT

37 °

rCONTROLLER

hypothalamus compares and triggers ~ffectors

ENVIRONMENT

radiation, 1 wind, etc.

OUTPUT

37 o

body heat

EFFECTORS T I behavioral, l ~ muscular, andl

"]metabolic l ]reactions ]

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 o f these has a direct application to the design o f 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 o f 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 o f a set point in human behavior. Hamner summarized a review of the research with the conclusion that "the most immediate, direct, and

motivational determinant o f task performance is the subject 's goal" (Hamner, 1974: 217). "Simply s tated" an experimental s tudy 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 contr ibute 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 cuniculum 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 expectat ions reflected in the goals.

2. LIMITATION OF INPUT

The complexi ty o f a system's control mechanism is relative to the variety or range of the system input. The more variety or disturbance per- mit ted 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 o f 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 "abili ty 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 t h a t they are all interested or willing to learn multiplication, we can expect to produce the desired learning ou tpu t 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

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, o f 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 o f decisions, it is desirable that the outcome of such assessment be a diagnostic profile o f s tudent achievement, rather than a unidimensional scale of success or failure.

Principle 3: The stability of an instructional system will be a function o f the frequency and sensitivity o f 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 photoelectr ic cell, it may be an on /o f f switch with only two possible values for the regulating variable. In bo th types, the faster the controller responds, the less likely it is that f luctuation 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 s lowdown 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 sys tem, the teacher makes decisions on the basis of feedback on learner achievement. A fully articulated curriculum will provide guidelines for such decisions; for example: "Adminis ter 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.

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 (McIntyre, 1975). Many natural systems contain a number of effect0rs, 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

the functions o f 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 o f 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 o f ou tpu t 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 just ify further discrimination. The "knowl- edge explosion", the rate of cultural change, growth of bacteria, multi- plication of rabbits, c r o w d behavior, the emergence of a media "star", vendettas, wars, civil unrest and repression, love and hate, all manifest the exponential growth typical o f 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 expectat ion 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 s tudent dropping out o f school mentally or physically, which eliminates the learning system, or to an equilibrium in which the s tudent 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 probabil i ty o f 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 over time 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 o f 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

RAW INPUT

F

INPUT~IMITER prerequisites exclude extremes

INPUT~ learner aptitudes, background, motivation

OUTPUT ihigh & stabl~ achievement &~ motivation I TM

~~PERATION instruction

SET POINT 1 goals I understood and accepted

CONTROLLER yes

EFFEC~- ~ remediation I

restores equilibrilgn

SENSORS ~ formative b

evaluation

"I

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 at tempted 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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Bloom, Benjamin S. (1976). Human Characteristics and School Learning. New York: McGraw Hill.

Bloom, Benjamin S. (1980). All Our Children Learning. New York: McGraw Hill. Cabanac, Michel (1972). "Thermoregulatory behavior," in J. Bligh and R. E. Moore (eds.),

Essays on Temperature Regulation. Amsterdam: North-Holland, pp. 19-36. Dockstader, Steven L., Nebeker, Delbert M. and Shumate, E. Chandler (1977). The Effects

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Esposito, Dominick (1973). "Homogeneous and heterogeneous ability grouping: principal findings and implications for evaluating and designing more effective educational environments," Review o f Educational Research 43: 163-179.

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Hamner, W. Clay (1974). "Goal setting, performance and satisfaction in an interdependent task," Organizational Behavior and Human Performance 12:217-230.

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Nielsen, Marius (1970). "Heat production and body temperature during rest and work," in James D. Hardy, A. Pharo Gagge, and Jan A. J. Stolwijk (eds.), Physiological and Behavioral Temperature Regulation. Springfield, IL: Charles C. Thomas, pp. 205-214.

Pekelis, V. (1974). Cybernetics A to Z. Moscow: Mir Publishers. Rawls, John (1971). A Theory of Justice. Cambridge, MA: Harvard University Press, 1971. Rowen, Hobart (1977). Teaching basics to India's farmers. Washington Post, 15 December

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