piaget (1972) - intellectual evolution from adolescence to adulthood

Human Development 2008;51:4047DOI: 10.1159/000112531Reprint of Human Development 1972;15:112

Key WordsCognitive development Adolescence Adulthood Logic Environmentaldifferences Individual differences

AbstractGrowing out of a childs cognitive devel-

opmental history, formal operations becomeestablished at about the age of 1215 years.Reflected in his ability to reason hypotheticallyand independently on concrete states ofaffairs, these structures may be representedby reference to combinatorial systems and to4-groups. The essence of the logic of culturedadults and the basis for elementary scientificthought are thereby provided. The rate atwhich a child progresses through the develop-mental succession may vary, especially fromone culture to another. Different children alsovary in terms of the areas of functioning towhich they apply formal operations, accordingto their aptitudes and their professional spe-cializations. Thus, although formal operations

are logically independent of the reality contentto which they are applied, it is best to test theyoung person in a field which is relevant to hiscareer and interests.

We are relatively well informed aboutthe important changes that take place in cog-nitive function and structure at adolescence.Such changes show how much this essentialphase in ontogenic development concerns allaspects of mental and psychophysiological evo-lution and not only the more instinctive, emo-tional or social aspects to which one often limitsones consideration. In contrast, however, weknow as yet very little about the period whichseparates adolescence from adulthood and wefeel that the decision of the Institution FONEMEto draw the attention of various research workersto this essential problem is extremely wellfounded.

In this paper we would first like to recallthe principal characteristics of the intellectualchanges that occur during the period from 1215

Intellectual Evolution fromAdolescence to Adulthood1

J. Piaget

Universit de Genve, Ecole de Psychologie et des Sciences de lEducation, Genve

Prof. Jean PiagetUniversit de GenveEcole de Psychologie et des Sciences de lEducation Palais WilsonCH-1211 Genve 14 (Switzerland)

Fax 41 61 306 12 34E-Mail [email protected]

2008 S. Karger AG, Basel0018716X/08/05110040$24.50/0

Accessible online at:www.karger.com/hde

1A French version of the article was presented at FONEME, 3rd International Convention, Milan 1970, and published in the proceedings(FONEME, Institution for Studies and Research in Human Formation, 20135, Via Bergamo 21, Milan, Italy). The English translation wasprepared by JOAN BLISS and HANS FURTH, to whom special thanks are due. The editors of Human Development gratefully acknowledgepermission by the author and FONEME to publish the English version.

years of age. These characteristics are too fre-quently forgotten as one tends to reduce the psy-chology of adolescence to the psychology ofpuberty. We shall then refer to the chief problemsthat arise in connection with the next period(1520 years); firstly, the diversification of apti-tudes, and secondly, the degree of generality ofcognitive structures acquired between 12 and 15years and their further development.

The Structures of Formal Thought

Intellectual structures between birth and theperiod of 1215 years grow slowly, but accordingto stages in development. The order of successionof these stages has been shown to be extremelyregular and comparable to the stages of anembryogenesis. The speed of development, how-ever, can vary from one individual to another andalso from one social environment to another; con-sequently, we may find some children whoadvance quickly or others who are backward, butthis does not change the order of succession ofthe stages through which they pass. Thus, longbefore the appearance of language, all normalchildren pass through a number of stages in theformation of sensorimotor intelligence which canbe characterized by certain instrumental behav-ior patterns; such patterns bear witness to theexistence of a logic which is inherent to the coor-dination of the actions themselves.

With the acquisition of language and theformation of symbolic play, mental imagery, etc.,that is, the formation of the symbolic function (or,in a general sense, the semiotic function), actionsare interiorized and become representations; thissupposes a reconstruction and a reorganizationon the new plane of representative thought.However, the logic of this period remains incom-plete until the child is 7 or 8 years old. The internalactions are still preoperatory if we take opera-tions to mean actions that are entirely reversible(as adding and subtracting, or judging that the dis-tance between A and B is the same as the distancebetween B and A, etc.). Due to the lack ofreversibility, the child lacks comprehension of theidea of transitivity (A C, if A B and B C)

and of conservation (for a preoperatory child, if theshape of an object changes, the quantity of matterand the weight of the object change also).

Between 78 and 1112 years a logic ofreversible actions is constituted, characterized bythe formation of a certain number of stable andcoherent structures, such as a classification sys-tem, an ordering system, the construction of natu-ral numbers, the concept of measurement of linesand surfaces, projective relations (perspectives),certain general types of causality (transmission ofmovement through intermediaries), etc.

Several very general characteristics distin-guish this logic from the one that will be consti-tuted during the pre-adolescent period (between 12and 15 years). Firstly these operations are con-crete, that is to say, in using them the child stillreasons in terms of objects (classes, relations,numbers, etc.) and not in terms of hypotheses thatcan be thought out before knowing whether theyare true or false. Secondly, these operations, whichinvolve sorting and establishing relations betweenor enumerating objects, always proceed by relatingan element to its neighboring elementthey can-not yet link any term whatsoever to any other term,as would be the case in a combinatorial system:thus, when carrying out a classification, a childcapable of concrete reasoning associates one termwith the term it most resembles and there is nonatural class that relates two very different objects.Thirdly, these operations have two types ofreversibility that are not yet linked together (in thesense that one can be joined with the other); thefirst type of reversibility is by inversion or nega-tion, the result of this operation is an annulment,for example, A A 0 or n n 0; thesecond type of reversibility is by reciprocity andthis characterizes operations of relations, forexample, if A B, then B A, or if A is to theleft of B, then B is to the right of A, etc.

On the contrary, from 1112 years to 1415years a whole series of novelties highlights thearrival of a more complete logic that will attain astate of equilibrium once the child reaches ado-lescence at about 1415 years. We must, there-fore, analyze this new logic in order tounderstand what might happen between adoles-cence and full adulthood.

41Reprint of Human Development1972;15:112

Intellectual Evolution from Adolescence to Adulthood

The principle novelty of this period is thecapacity to reason in terms of verbally statedhypotheses and no longer merely in terms of con-crete objects and their manipulation. This is adecisive turning point, because to reason hypo-thetically and to deduce the consequences thatthe hypotheses necessarily imply (independent ofthe intrinsic truth or falseness of the premises) isa formal reasoning process. Consequently thechild can attribute a decisive value to the logicalform of the deductions that was not the case inthe previous stages. From 78 years, the child iscapable of certain logical reasoning processes butonly to the extent of applying particular opera-tions to concrete objects or events in the immedi-ate present: in other words, the operatory form ofthe reasoning process, at this level, is still subor-dinated to the concrete content that makes up thereal world. In contrast, hypothetical reasoningimplies the subordination of the real to the realmof the possible, and consequently the linking ofall possibilities to one another by necessaryimplications that encompass the real, but at thesame time go beyond it.

From the social point of view, there is alsoan important conquest. Firstly, hypothetical rea-soning changes the nature of discussions: a fruit-ful and constructive discussion means that byusing hypotheses we can adopt the point of viewof the adversary (although not necessarily believ-ing it) and draw the logical consequences itimplies. In this way, we can judge its value afterhaving verified the consequences. Secondly, theindividual who becomes capable of hypotheticalreasoning, by this very fact will interest himselfin problems that go beyond his immediate field ofexperience. Hence, the adolescents capacity tounderstand and even construct theories and toparticipate in society and the ideologies of adults;this is often, of course, accompanied by a desireto change society and even, if necessary, destroyit (in his imagination) in order to elaborate a bet-ter one.

In the field of physics and particularly in theinduction of certain elementary laws (many exper-iments have been carried out under the direction ofB. INHELDER on this particular topic), the differencein attitude between children of 1215 years,

already capable of formal reasoning, and childrenof 710 years, still at the concrete level, is verynoticeable. The 7- to 10-year-old children whenplaced in an experimental situation (such as whatlaws concern the swing of a pendulum, factorsinvolved in the flexibility of certain materials,problems of increasing acceleration on an inclinedplane) act directly upon the material placed infront of them by trial and error, without dissociat-ing the factors involved. They simply try to clas-sify or order what happened by looking at theresults of the co-variations. The formal level chil-dren, after a few similar trials stop experimentingwith the material and begin to list all the possiblehypotheses. It is only after having done this thatthey start to test them, trying progressively to dis-sociate the factors involved and study the effectsof each one in turnall other factors remainingconstant.

This type of experimental behavior, directedby hypotheses which are based on more or lessrefined causal models, implies the elaboration oftwo new structures that we find constantly in for-mal reasoning.

The first of these structures is a combinator-ial system, an example of which is clearly seenin the set of all subsets, (2n2 or the simplexstructure). We have, in fact, previously men-tioned that the reasoning process of the child atthe concrete level (710 years old) progresses bylinking an element with a neighboring one, andcannot relate any element whatsoever to anyother. On the contrary, this generalized combina-torial ability (1 to 1, 2 to 2, 3 to 3, etc.) becomeseffective when the subject can reason in a hypo-thetical manner. In fact, psychological researchshows that between 12 and 15 years the pre-adolescent and adolescent start to carry out oper-ations involving combinatorial analysis,permutation systems, etc. (independent of allschool training). They cannot, of course, figureout mathematical formulas, but they can discoverexperimentally exhaustive methods that work forthem. When a child is placed in an experimentalsituation where it is necessary to use combinato-rial methods (for example, given 5 bottles ofcolorless, odorless liquid, 3 of which combine tomake a colored liquid, the fourth is a reducing

42 Reprint of Human Development1972;15:112

Piaget

agent and the fifth is water), the child easily dis-covers the law after having worked out all thepossible ways of combining the liquids in thisparticular case.

This combinatorial system constitutes anessential structure from the logical point of view.The elementary systems of classification andorder observed between 7 and 10 years, do notyet constitute a combinatorial system. Prepositionallogic, however, for two propsitions p and qand their negation, implies that we not only con-sider the 4-base associations (p and q, p and notq, not p and q, not p and not q) but also the 16combinations that can be obtained by linkingthese base associations 1 to 1, 2 to 2, 3 to 3 (withthe addition of all 4-base associations and theempty set). In this way it can be seen that impli-cation, inclusive disjunction and incompatibilityare fundamental propositional operations thatresult from the combination of 3 of these baseassociations.

At the level of formal operations it isextremely interesting to see that this combinator-ial system of thinking is not only available andeffective in all experimental fields, but that thesubject also becomes capable of combiningpropositions: therefore, propositional logicappears to be one of the essential conquests offormal thought. When, in fact, the reasoningprocesses of children between 1112 and 1415years are analyzed in detail it is easy to find the16 operations or binary functions of a bivalentlogic of propositions.

However, there is still more to formalthought: when we examine the way in which sub-jects use these 16 operations we can recognizenumerous cases of the 4-group which are isomor-phic to the Klein group and which reveal them-selves in the following manner. Let us take, forexample, the implication p q, if this staysunchanged we can say it characterized the iden-tity transformation I. If this proposition ischanged into its negation N (reversibility bynegation or inversion) we obtain N p and not q.The subject can change this same propositioninto its reciprocal (reversibility by reciprocity)that is R q p; and it is also possible tochange the statement into its correlative (or dual),

namely C not p and q. Thus, we obtain a com-mutative 4-group such that CR N, CN R,RN C and CRN I. This group allows thesubject to combine in one operation the negationand the reciprocal which was not possible at thelevel of concrete operations. An example of thesetransformations that occurs frequently is thecomprehension of the relationship betweenaction (I and N) and reaction (R and C) in physicsexperiments; or again, the understanding of therelationship between two reference systems, forexample: a moving object can go forwards orbackwards (I and N) on a board which itself cango forwards or backwards (R and C) in relation toan exterior reference system. Generally speakingthe group structure intervenes when the subjectunderstands the difference between the can-celling or undoing of an effect (N in relation to I)and the compensation of this effect by anothervariable (R and its negation C) which does noteliminate but neutralizes the effect.

In concluding this first part we can see thatthe adolescents logic is a complex but coherentsystem that is relatively different from the logicof the child, and constitutes the essence of thelogic of cultured adults and even provides thebasis for elementary forms of scientific thought.

The Problems of the Passage fromAdolescent to Adult Thought

The experiments on which the above-mentioned results are based were carried out withsecondary school children, 1115 years, takenfrom the better schools in Geneva. However,recent research has shown that subjects fromother types of schools or different social environ-ments sometimes give results differing more or lessfrom the norms indicated; for the same experi-ments it is as though these subjects had stayed atthe concrete operatory level of thinking.

Other information gathered about adults inNancy, France, and adolescents of different levelsin New York has also shown that we cannot gen-eralize in all subjects the conclusion of ourresearch which was, perhaps, based on a some-what privileged population. This does not mean



that our observations have not been confirmed inmany cases: they seem to be true for certain pop-ulations, but the main problem is to understandwhy there are exceptions and also whether theseare real or apparent.

A first problem is the speed of development,that is to say, the differences that can be observedin the rapidity of the temporal succession of thestages. We have distinguished 4 periods in thedevelopment of cognitive functions (see begin-ning of part 1): the sensorimotor period before theappearance of language; the preoperatory periodwhich, in Geneva, seems on the average to extendfrom about 12 to 67 years; the period ofconcrete operations from 78 to 1112 years(according to research with children in Genevaand Paris) and the formal operations period from1112 to 1415 years as observed in the schoolsstudied in Geneva. However, if the order of suc-cession has shown itself to be constanteachstage is necessary to the construction of the fol-lowing onethe average age at which children gothrough each stage can vary considerably fromone social environment to another, or from onecountry or even region within a country toanother. In this way Canadian psychologists inMartinique have observed a systematic slownessin development; in Iran notable differences werefound between children of the city of Teheran andyoung illiterate children of the villages. In Italy,N. Peluffo has shown that there is a significantgap between children from regions of southernItaly and those from the north; he has carried outsome particularly interesting studies indicatinghow, in children from southern families migratingnorth, these differences progressively disappear.Similar comparative research is at present takingplace in Indian reservations in North America, etc.

In general, a first possibility is to envisage adifference in speed of development without anymodification of the order of succession of thestages. These different speeds would be due tothe quality and frequency of intellectual stimula-tion received from adults or obtained from thepossibilities available to children for spontaneousactivity in their environment. In the case of poorstimulation and activity, it goes without sayingthat the development of the first 3 of the 4 periods

mentioned above will be slowed down. When itcomes to formal thought, we could propose thatthere will be an even greater retardation in its for-mation (for example, between 15 and 20 yearsand not 11 and 15 years); or that perhaps inextremely disadvantageous conditions, such atype of thought will never really take shape orwill only develop in those individuals whochange their environment while development isstill possible.

This does not mean that formal structuresare exclusively the result of a process of socialtransmission. We still have to consider the spon-taneous and endogenous factors of constructionproper to each normal subject. However, the for-mation and completion of cognitive structuresimply a whole series of exchanges and a stimulat-ing environment; the formation of operationsalways requires a favorable environment for co-operation, that is to say, operations carried out incommon (e.g., the role of discussion, mutual crit-icism or support, problems raised as the result ofexchanges of information, heightened curiositydue to the cultural influence of a social group,etc.). Briefly, our first interpretation would meanthat in principle all normal individuals are capa-ble of reaching the level of formal structures onthe condition that the social environment andacquired experience provide the subject with thecognitive nourishment and intellectual stimula-tion necessary for such a construction.

However, a second interpretation is possiblewhich would take into account the diversificationof aptitudes with age, but this would meanexcluding certain categories of normal individu-als, even in favorable environments, from thepossibility of attaining a formal level of thinking.It is a well-known fact that the aptitudes of indi-viduals differentiate progressively with age. Sucha model of intellectual growth would be compa-rable to a fully expanded hand fan, the concentriclayers of which would represent the successivestages in development whereas the sectors, open-ing wider towards the periphery, correspond tothe growing differences in aptitude.

We would go so far as to say that certainbehavior patterns characteristically form stageswith very general properties: this occurs until a


Piaget

certain level in development is reached; from thispoint onwards, however, individual aptitudesbecome more important than these general char-acteristics and create greater and greater differ-ences between subjects. A good example of thistype of development is the evolution of drawing.Until the stage at which the child can representperspectives graphically, we observe a very gen-eral progress to the extent that the draw a mantest, to cite a particular case as an example, canbe used as a general test of mental development.However, surprisingly large individual differ-ences are observed in the drawings of 13-to 14-year-old children, and even greater differenceswith 1920 year olds (e.g., army recruits): thequality of the drawing no longer has anything todo with the level of intelligence. In this instancewe have a good example of a behaviour patternwhich is, at first, subordinate to a general evolu-tion in stages [cf. those described by LUQUET andother authors for children from 23 until about89 years] and which, afterwards, graduallybecomes diversified according to criteria of indi-vidual aptitudes rather than the general develop-ment common to all individuals.

This same type of pattern occurs in severalfields including those which appear to be morecognitive in nature. One example is provided bythe representation of space which first dependson operatory factors with the usual 4 intellectualstagessensorimotor (cf. the practical group ofdisplacements), preoperatory, concrete opera-tions (measure, perspectives, etc.) and formaloperations. However, the construction of spacealso depends on figurative factors (perception andmental imagery) which are partially subordinatedto operatory factors and which then become moreand more differentiated as symbolical and repre-sentative mechanisms. The final result is that forspace in general, as for drawing, we can distin-guish a primary evolution characterized by thestages in the ordinary sense of the term, and thena growing diversification with age due to gradu-ally differentiating aptitudes with regard toimaged representation and figurative instruments.We know, for example, that there exist bigdifferences between mathematicians in theway in which they define geometrical intuition:

POINCAR distinguishes two types of mathemati-cians the geometricians, who think more con-cretely and the algebrists, or analysts, whothink more abstractly.

There are many other fields in which wecould also think along similar lines. It becomespossible at a certain moment, for example, to dis-tinguish between adolescents who, on the onehand, are more talented for physics or problemsdealing with causality than for logic or mathe-matics and those who, on the other hand, showthe opposite aptitude. We can see the same ten-dencies in questions concerning linguistics, liter-ature, etc.

We could, therefore, formulate the followinghypothesis: if the formal structures described inpart 1 do not appear in all children of 1415 yearsand demonstrate a less general distribution thanthe concrete structures of children from 710years old, this could be due to the diversificationof aptitudes with age. According to this interpre-tation, however, we would have to admit that onlyindividuals talented from the point of view oflogic, mathematics and physics would manage toconstruct such formal structures whereas literary,artistic and practical individuals would be inca-pable of doing so. In this case it would not be aproblem of under-development compared to nor-mal development but more simply a growingdiversification in individuals, the span of apti-tudes being greater at the level of 1215 years,and above all between 15 and 20 years, than at710 years. In other words, our fourth period canno longer be characterized as a proper stage, butwould already seem to be a structural advance-ment in the direction of specialization.

But there is the possibility of a third hypoth-esis and, in the present state of knowledge, thislast interpretation seems the most probable. Itallows us to reconcile the concept of stages withthe idea of progressively differentiating aptitudes.In brief, our third hypothesis would state that allnormal subjects attain the stage of formal opera-tions or structuring if not between 1112 to1415 years, in any case between 15 and 20years. However, they reach this stage in differentareas according to their aptitudes and theirprofessional specializations (advanced studies or



different types of apprenticeship for the varioustrades): the way in which these formal structuresare used, however, is not necessarily the same inall cases.

In our investigation of formal structureswe used rather specific types of experimental sit-uations which were of a physical and logical-mathematical nature because these seemed to beunderstood by the school children we sampled.However, it is possible to question whether thesesituations are, fundamentally, very general andtherefore applicable to any school or professionalenvironment. Let us consider the example ofapprentices to carpenters, locksmiths, or mechan-ics who have shown sufficient aptitudes for suc-cessful training in the trades they have chosen butwhose general education is limited. It is highlylikely that they will know how to reason in ahypothetical manner in their speciality, that is tosay, dissociating the variables involved, relatingterms in a combinatorial manner and reasoningwith propositions involving negations and reci-procities. They would, therefore, be capable ofthinking formally in their particular field,whereas faced with our experimental situations,their lack of knowledge or the fact they have for-gotten certain ideas that are particularly familiarto children still in school or college, would hinderthem from reasoning in a formal way, and theywould give the appearance of being at the con-crete level. Let us also consider the example ofyoung people studying lawin the field of juridi-cal concepts and verbal discourse their logicwould be far superior to any form of logic theymight use when faced with certain problems inthe field of physics that involve notions they cer-tainly once knew but have long since forgotten.

It is quite true that one of the essential char-acteristics of formal thought appears to us to bethe independence of its form from its reality con-tent. At the concrete operatory level a structurecannot be generalized to different heterogenouscontents but remains attached to a system ofobjects or to the properties of these objects (thusthe concept of weight only becomes logicallystructured after the development of the concept ofmatter, and the concept of physical volume afterweight): a formal structure seems, in contrast,

generalizable as it deals with hypotheses.However, it is one thing to dissociate the formfrom the content in a field which is of interest tothe subject and within which he can apply hiscuriosity and initiative, and it is another to be ableto generalize this same spontaneity of researchand comprehension to a field foreign to the sub-jects career and interests. To ask a future lawyerto reason on the theory of relativity or to ask astudent in physics to reason on the code of civilrights is quite different from asking a child togeneralize what he has discovered in the conser-vation of matter to a problem on the conservationof weight. In the latter instance it is the passagefrom one content to a different but comparablecontent, whereas in the former it is to go out ofthe subjects field of vital activities and enter atotally new field, completely foreign to his inter-ests and projects. Briefly, we can retain the ideathat formal operations are free from their con-crete content, but we must add that this is trueonly on the condition that for the subjects the sit-uations involve equal aptitudes or comparablevital interests.

Conclusion

If we wish to draw a general conclusionfrom these reflections we must first say that, froma cognitive point of view, the passage from ado-lescence to adulthood raises a number of unre-solved questions that need to be studied in greaterdetail.

The period from 15 to 20 years marks thebeginning of professional specialization and con-sequently also the construction of a life programcorresponding to the aptitudes of the individual.We now ask the following critical question: Canone demonstrate, at this level of development asat previous levels, cognitive structures commonto all individuals which will, however, be appliedor used differently by each person according tohis particular activities?

The reply will probably be positive but thismust be established by the experimental methodsused in psychology and sociology. Beyond that,the next essential step is to analyze the probable


Piaget



processes of differentiation: that is to say,whether the same structures are sufficient for theorganization of many varying fields of activitybut with differences in the way they are applied,or whether there will appear new and specialstructures that still remain to be discovered andstudied.

It is to the credit of the FONEME Institutionto have realized the existence of these problemsand to have understood their importance andcomplexity, particularly as, generally speaking,developmental psychology believed that its workwas completed with the study of adolescence.Fortunately, today, certain research workers are

conscious of these facts and we can hope to knowmore about this subject in the near furture.

Unfortunately the study of young adults ismuch more difficult than the study of the youngchild as they are less creative, and already part ofan organized society that not only limits them andslows them down but sometimes even rousesthem to revolt. We know, however, that the studyof the child and the adolescent can help us under-stand the further development of the individual asan adult and that, in turn, the new research onyoung adults will retroactively throw light onwhat we already think we know about earlierstages.

piaget (1972) - intellectual evolution from adolescence to adulthood

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