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Extraversion: Sociability and Impulsivity?Robert Plomin

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To cite this article: Robert Plomin (1976): Extraversion: Sociability and Impulsivity?, Journal of

Personality Assessment, 40:1, 24-30

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Journal o f Personality Assessment, 1976,4O, 1

Extraversion: Sociability and Impulsivity?

ROBERT PLOMIN

Institute for Behavioral GeneticsUniversity of Colorado, Boulder

Summary: The sociability and impulsivity components of extraversion were studied. Thirty

experimental items were written to assess different aspects of sociability and impulsivity.These items, along with the 24 extraversion items of the MPI, were administered to 146

college students. Facto r analyses of th e experimental items indicated that neither sociabilitynor impulsivity is unitary. Correlations among these sociability and impulsivity factors andthe MPI extraversion item s indicated t hat MPI extraversion is essentially a measure of oneaspect of sociability: th e qua ntity of social relationships. Extraversion touches on bu t doesnot adequately sample either the intensity (quality) of social relationships or aspects ofimpulsivity.

"You only get ou t of factor analysiswhat you put in" is an underrated m aximin personality research and te nds to beswept away in a swirl of statisticalsophistry. The maxim assumes greaterimportance when one considers thatmuch of our modern definition of person-ality stems from factor analytic research(e.g., Cattell, 1 94 6; Eysenc k, 1947).

From the welter of factors emergingfrom factor analysis, extraversion hascome into sharpest focus. The extraver-sion dimension has been advocated pri-marily by Eysen ck (e.g., 1973) and hasbeen measured most often by his factor-analyzed self-report questionnaires. Al-though most of the extraversion researchduring the last two decades has beenaimed at testing Eysenck's neurologicaltheory of extraversion (e.g., E ysenck,1967), the descriptive foundation for thistheoretical framework rests on his earlyfactor analytic research. Let us examinewhat was "put in" these factor analyses.

In a factor analysis of ratings ofneurotic symptoms, Eysenck (1947) dis-covered a bipolar factor of dysthyrnic-hyste ric symptom s. He concludeci thatthis dichotomy was closely related toJung's concept of extraversion. In 1953

Eysenck fo und tha t several scales of theGuilford-Martin (Guilford, 1940) person-ality questionnaire were related to thedysthymic-hysteric dichotomy . One scale,Rhathymia, loaded most highly on anextraversion factor. In a factor analysisthat included 24 Rhathymia items,Eysenck (1956) derived a factor which

became the extraversion scale of hisMaudsley Personality Inventory (MPI)(Eysenck, 1959), which was later re-factored and revised to produce theEysenck Personality Inventory (Eysenck& Eysenck, 1963a). Thus, for Eysenck'sfactor analyses, the major extraversioningredient was Guilford's Rhathymiascale.

After the 24 items were settled into a nextraversion scale, two factors began toemerge. Eysenck and Eysenck (1963b)labelled these factors "sociability" and"impulsivity." They reported a correla-tion of .47 betwee n the 1 4 highest-loading impulsivity items and the 14highest-loading sociability items. How-

ever, other researchers have reportedlower correlations (e.g., Farley, 1970).There are several arguments for consider-ing these components of extraversionseparately (Buss & Plomin, 197 5). Inaddition, we should go further and askwhether the limited pool of items fromwhich these components were extractedadequately represents all aspects ofsociability and impulsivity.

A logical analysis of sociability andimpulsivity reveals their com plexity (Buss& Plomin, 1975). One aspect of soci-ability is the

quantityof social relation-

ships (gregariousness); another element isthe quality (intensity) of the interaction.Some people need intense relationships,while others are content with superfici-ality. Impulsivity may also involve severalcomponents: (a) Impulse control. Impul-sives may have difficulty in controlling



ROBERT PLOMIN 25

Table 1

EASI Sociability and Imp ulsivity Items -mpulse Contro l

a 12. I often buy things on impulse.

a 18. My impu lses often get the better of me.

26 . 1 ike to spend my money right away rather than save it for long-range goals.a3 6. I have trouble resisting my cravings (for food , cigarettes, etc.).

a4 5. When I try self-con trol, it generally works. (reversled)

a5 2. I can tolerate frustration better than most. (reversed)

Sensation-seeking

a 4. 1some times do "crazy" things just t o be different.

10. 1 tend t o avoid anything risky. (reversed)

a2 7. 111 try anything once.

a3 2. I generally seek new and exciting experiences and sensations.

a3 5. Routine jobs really bug me.

Decision Time--a

1, I often have trouble making up m y mind. (reversed)

a20. I usually mak e quick decisions.

54. Before I do some thing, I like to have every detail spelled out. (reversed)

a48. It bugs me when people take a long time to make up their m inds.

"49. I tend to hop from interest to interest quickly.--Sociability: Quantity-

7. 1generally prefer to d o things alone. (reversed)

a 13. I tend t o be shy. (reversed)

a 15 . I almost always prefer to work and study with o thers rather tha n alone.a 19. I tend to be a loner. (reversed)

a41. I prefer parties with lots of people.

a4 2. I make friends very easily and quickly.

a47. I have more friends than most people.

a5 1. 1am very sociable.

a5 3. I like to feel independent of people. (reversed)

Sociability: Quality

a 8. People 1 ike best express a lo t of affection.

a 14. With people th at I kno w well, I am a very "warm" person.

a2 5. I tend to be a very affectionate person.a4 0. It is importan t for me to feel very close to people I like.

a4 3. I always seem to get involved with others' problems.

a Loaded above .30 on its appropriate factor and no higher on the othe r factors.

Factor loadings are available from the author.



impulses involved in delayin g gratification(Mischel, 1961) and in resisting tempta-tion (Aronfreed & Reber, 1965). (b)Decision time. Impulsives may mak e snapdecisions. Kagan's (e.g., Kagan, Pearson,& Welch, 1966) dimension of reflection-impulsivity may be related to decisiontime. (c) Sensation-seeking, Impulsivesmay be sensation-seekers. Zuckerman(1971) has studied individual differencesin "optimal stimulation level."

The purpose of the present study wasthreefo ld: (a) to assess the tw o aspects ofsociability and the three aspects of im-pulsivity, (b) to assess their interrelation-ships, and (c) to assess their relationshipto the sociability and impulsivity factorsof extraversion.

Method

Items from an experimental question-naire called the EASI Temperament Sur-vey (Buss & Plomin, 1975) were used totap the impulse control (Ic), sensation-seeking (Is) and decision-tim e (Id) corn-ponents of impulsivity and the gregarious-ness (S-quantity) and inten sity (S-quality)components of sociability. These 30items and the 24 extraversion items fromthe M audsley Personality Inventory (MPI)were administered to 14 6 college students(70 men and 76 women) enrolled in anintroductory psychology course at the

University of Texas at Austin. The EASIsociability and impulsivity items and theMPI extraversion items were factoranalyzed separately, using both orthogo-nal and oblique rotations. The computerprograms were part of the StatisticalPackage for the So cial Sciences (Me,Bent, & Hull, 1970).' The factorial struc-tures of the EASI sociability and impul-sivity components were examined, andthe factored scales were correlated witheach other and with factors from the MPIextraversion items .

Standard options were employed: Com-rnunality was estimated using an iterativeprocess, Kaiser's Varimax procedure was usedfor orthogonal rotations, and the delta value foroblique rotations was set at zero. Factors wereextracted for rotation to the criterion of an

eigenvalue of 1.0.

Extraversion: Sociability an d Impulsivity?

Results

EA SI Sociability and Impulsivity

Table 1 lists the EASI sociability items(S-quantity and S-quality) and impul-sivity items (Ic, Is, Id). These items hadbeen factor analyzed previously (Plomin,1974), and their factor structure corre-

sponded to their a priori placement. Thepresent sample replicated these earlierfindings with few exceptions. For thisanalysis, as for subsequent factoranalyses, the oblique rotations yieldedessentially the same results as the orthog-onal rotations. Only the oblique loadingsare discussed, because oblique rotationsdo n ot impose orthogonality on the data;this permits intercorrelations of thefactored scales. Space does not permitinclusion of the factor loadings in thetables, but they are available from the

author.The factor analysis of the sociability

items yielded three factors. The firstfactor was S-quantity, involving five ofthe nine a priori items (13, 41, 42, 47,51). The second factor was S-quality,which included all five of the a prioriitems. A third factor, called a "loner"factor (S-loner), emerged from theremaining S-qua ntity items.

The a priori components of impul-sivity were also verified by factor

analysis. The first factor consisted ofthree items, one from each of the three apriori scales of impulsivity. This com-posite factor was ignored because two ofthe three items also loaded on factorsreflecting their respective a priori cate-gories. The second factor was clearly Ic,with five of the six appropriate itemsloading above .39 and the sixth itemloading .25. I s was also clearly delineated:All five of the a priori sensation-seekingitems and no other items loaded on thethird factor. Id items split into the fou rthand fifth factors, but a decision was madeto retain the four items (1, 20, 48, 49 )loading on these two factors as a prelimi-nary measure of decision time. All the apriori Ic and Is items were retained fortheir respective scales.

Table 2 presents the mterco~relatiossamong the factored sociability and



ROBERT PLOMIN 27

Table 2

Correlations among the EASI Soc iability and impulsivityFactored Scales (N= 146)

EASI Soc iability

Quantity Quality "Loner"1-

impulsivity scales. There were m arginallysignificant interrelationships within thecomponents of sociability and impulsiv-ity. Although all the correlations weresignificant, none except the correlationbetween S-quality and S-loner was greaterthan .30. Moreover, the correlations be-

tween sociability and impulsivity wereeven lower: Only one of the correlationswas significant, and the average correla-tion was only .08.

We may draw two conclusions fromthese data. First, there are several com-ponents in both sociability and impulsiv-ity, because the components of each arefactorially distinct and are only margin-ally interrelated. Second, correlations be-tween the components of impulsivity andthe components of sociability are low andinsignificant, with only one exception.

This implies that, when care is taken towrite items to assess the components ofsociability and impulsivity, the twodimensions are inde pendent.

MPI Extraversion

We have seen that neither so ciabilitynor impulsivity appears to be unitary.

EASI Impu lsivity--ImpulseControl

Sensation-Seeking

De'cisionTime

The major question of interest, then, iswhich components of socialnlity andimpulsivity underlie extraversion as mea-sured by Eysenck. The factor analysis ofthe MPI extraversion items yielded sevenfactors, although the last three factorsculled were not interpreted. The first

factor represented the sociability factorthat has been found by other investiga-tors. It included seven items (MPI items4, 9 , 14, 20, 22, 26, 38) that loadedabove .30 on that factor and loaded onno other factor. The highest-loading itemsincluded having many social engagementsand taking the initiative in making newfriends. This set of items is referred tohere as "MPI sociability."

The impulsivity factor that other re-searchers have found among extraversionitems was more finely differentiated inthe present study. The second factorincluded three items (MPI items 8, 24,42) which referred to taking workcasually or as a matter of life or death.The third factor also included three items(MPI items 1, 12, 16); these involvedpreference for rapid action. The fourth



28 Extraversion: Sociability and Impulsivity?

Table 3

Correlations Between EASI Sociability and Impulsivity Components vs.

Maudsley Personality Inventory (MPI)

Sociability, Liveliness, and Total Extraversion Scores (N = 146)

MPI Scales

MPI

Sociability

MPI

Liveliness

MPI

Extraversion

EASI Sociability Factors

Quantity Quality

factor included five items (MPI items 8,32, 44, 46, 48) which involved liveliness,having a ready answer, and playingpranks. Both the second and third factorsinvolved doublets consisting of twosimilar items. For this reason, a decisionwas made to use the fourth factor as an"MPI impulsivity" factor, even thoughthis factor is better labelled "liveliness"rather than "impulsivity." (We will alsoreport an MPI score composed of all ofthese impulsivity-related items - despitethe fact that they have been differenti-ated factorially in the present study - n

order to make our results more compar-able to those of previous investigationswhich did not differentiate these factors.)

To what extent do our MPI sociabilityand impulsivity factors resemble thosefound by other researchers? The MPIsociability factor of the present study isnearly identical to the sociability factorfound by Eysenck and Eysenck (1963b)because five of the six highest-loadingsociability items (4, 9, 14, 20, 22, 36)from the Eysenck and Eysenck studywere included among the seven itemsused to define the MPI sociability factor

"Loner"

.3gb

.2sb

.37b

EASI Impulsivity Factors

Impulse

Control

.04

.15

.09

Sensation.

Seeking

.30b

.27b

.3sb

Decision

Time

in the present study. Although the fiveitems of our MPI liveliness factor onlyoverlapped with one of the six highest-loading impulsivity items (1, 5, 12, 34,42, 44) from the Eysenck and Eysenckstudy, the correlation between the twosets of items was .72, suggesting sub-stantial covariance. In the Eysenck andEysenck study, the sociability and im-pulsivity clusters correlated .47; in ourstudy, the MPI sociability and MPI live-liness factors correlated .57.

The Relationship Between EASI and MPI

Now we can turn to the major ques-tion: Which components of sociabilityand impulsivity underlie the two factorsof extraversion? Table 3 presents thecorrelations between S-quantity,S-quality, S-loner, Ic, Is, and Id, on theone hand, and MPI sociability, liveliness,and total extraversion on the other. MPIsociability was significantly correlatedwith all three EASI sociability factors,but it was much more closely allied withthe S-quantity factor (correlation of 31).Thus, the sociability items of the MPIextraversion scale seem to converge on



ROBERT PLOMIN

the quantity of social relationships ratherthan the quality of relationships.

Turning to the second row of Table 3,it is apparent that the MPI livelinessfactor is n~ota measure of impulsivity.Although MPI liveliness was marginallybut significantly correlated with sensa-tion-seeking, it is not significantly corre-lated with either impulse control or de-cision time. Moreover, MPI liveliness ishighly correlated with S-quantity. Thissuggests again that extraversion items -even the less "pure" sociability item s -focus on the quantity of social relation-ships. This effect is not limited to theMPI impulsivity items in the livelinessfactor of the present study: When all theMPI impulsivity items (from factors 2,3,and 4) were correlated with the EASIfactors, a similar pattern and magnitude

of correlations emerged. Thus, the com-ponent of extraversion that has beenlabelled "i~~~pulsivity"s related more toan aspect of sociability than t o any of thecomponents of impulsivity.

The third row of Table 3 generalizesthe preceding results to the total MPIextraversion scores. The correlationsclearly indicate that S-quantity is fore-most among the extraversion items (cor-relation of .81), although lower butsignificant correlations were obtainedwith all the other scales except impulse

control.Finally, all correlational and factoranalytic work was reanalyzed separatelyby gender. The pattern of results for menand women did not differ substantiallyfrom the results just reporte d.

Discussion

The results clearly indicate that extra-version, at least as measured by the MPI,is essentially a measure of one type ofsociability - the quantity of socialrelationships. It touches on but does not

at all adequately sample either the qualityof social relationships or aspects ofimpulsivity.

These results also point out the limitedusefulness of factor analysis. Eysenck'sfactor analytic research suggested thatextraversion is an important dimension ofpersonality. Subsequent factor analyses

indicated that extraversion is not unitaryand that it consists of primary factors,sociability and impulsivity, which arehighly correlated. In the present study,we have shovvn that, when the compo-nents of sociability and impulsivity areanalyzed and adequately represented inthe factor analyses, they emerge as sepa-rate factors. Moreover, sociability andimpulsivity were essentially uncorrelated.As oth ers have note d, facto r analysis onlydescribes which items of those sampledtend to be answered in a similar direction.It cannot create dimensions of person-ality. Guilforcl (e.g., Guilford & Zimmer-man, 1956) advocated a more reasonableuse of factor analysis as a tool to verifythe coherence of logically derived traits.We subscribe to this view.

The self-report data of the present

study require confirmation from ratingdata and experimental criteria, but it issafe to assert that we have much to learnabout both sociability and impulsivity.For example, one question concerns theheritability of the traits. There is con-siderable evidence to suggest that soci-ability is to some extent inherited (e.g.,reviewed in Scarr, 1969); however, theevidence conc~erning the heritab ility ofimpulsivity is mixed and inconclusive(reviewed in Buss & Plomin, 1975).Although evidence bearing on the inheri-

tance of the sulbcomponents of sociabilityand impulsivity is for the most partlacking, there is a sugge stion th at m osthave an inherited aspect (Plomin, 1974).Moreover, a unique analysis (Horn,Plomin, & Rosenman, in press) indicatedthat the consistent evidence for the herit-ability of sociability is due to the S-quantity component rather than theS-quality component, although it ispossible that their result was due to thegeneral neglect of the quality (intensity)aspects of relationships as measured by

S-quality. Clearly, there is much to learnabout inheritance of these traits andparticularly, about covariance amongthem.

Another question concerns thedevelopmental (course of the com pone ntsof sociability and impulsivity. Forexample, impulsivity is the focal point of



the socialization process, with some com -ponents seeming to be emphasized morethan others. Impulse control is crucialbecause it involves delay of gratificationand resistance to temptation. Sensation-seeking, however, may be som ewhat moretolerable.

Finally, gender differences may beimportant, particularly within a develop-mental perspective. For example, in thepresent study college men and women didnot differ in S-quan tity, bu t collegewomen rated themselves considerablyhigher on S-quality (t = 14.7, df = 1, r44,p < .001). This suggests that the tra-ditional gender stereotype of women asmore sociable may be based on thequality rather than the quantity of socialrelationships.

Some research on these questions is in

progress; other research and theoryaddressing these questions have been re-ported (Buss & Plomin, 1975).

References

Aronfreed, J., & Reber, A. Internalized be-havior suppression and the timing of socialpunishment. Journal of Personality andSocial Psychology, 1965 ,1, 3-16.

Buss, A., & Plomin, R. A temperament theoryof personality development. New York:Wiley Interscience, 1975.

Cattell, R. B. Description and measurement ofpersonali ty . Yonkers-on-Hudson, N.Y.:World Book, 1946.

Eysenck, H. J. Dimensions of personality.London: Routledge and Kegal Paul, 1947.

Eysenck, H. J. The structure o f hum an person-ality. London: Methuen, 1953.

Eysenck, H. J. The questionnaire measurementof neuroticism and extraversion. Revista dePsicologia, 1956 ,50, 113-140.

Eysenck, H. J. The Maudsley Personality Inven-tory. London: University of London Press,1959.

Eysenck, H. J. The biological basis of person-ality. Springfield, Ill.: Charles C. Thomas,1967.

Extraversion: Sociability and Impulsivity?

Eysenck, H. J. Historical introduction. In H. J.Eysenck (Ed.), Eysenck on extraversion.New York: John Wiley, 1973.

Eysenck, H. J., & Eysenck, S. B.Manual for theEysenck Personality Inventory. San Diego:Educational and Industrial Testing Service,1963a.

Eysenck, S. B., & Eysenck, H. J. On the dualnature of extraversion. British Journal of

Social and Clinical Psych ology, 1963b, 2,46-55.

Farley, F. H. Further investigation of the twopersonae of extraversion. British Journal ofSocial and Clinical Psychology, 1970, 9,377-379.

Guilford, J. P. Inventory of factors STDCR.Beverly Hills, Calif.: Sheridan Supply, 1940.

Guilford, J. P., & Zimmerman, W. S. Fourteendimensions of temperament. PsychologicalMonographs, 1956, 70 (Whole No. 417).

Horn, J., Plomin, R., & Rosenman, R. Herit-ability of personality traits in adult maletwins. Behavior Genetics, in press.

Kagan, J., Pearson, L., & Welch, L. Conceptualimpulsivity and inductive reasoning. ChildDevelopment, 1966,37, 583-594.

Mischel, W. Reference for delayed reinforce-ment and social responsibility. Journal ofAbnorm al and Social Psychology, 1961, 62,1-7.

Nie, N., Bent, D., & Hull, C. Statistical packagefor the social sciences. New York: McGraw-Hill, 1970.

Plornin, R. A temperament theory o f person-ality developm ent: Parent-child nteractions.Unpublished doctoral dissertation, Univers-ity of Texas at Austin, 1974.

Scarr, S. Social introversion-extrave~sion s aheritable response. Child Development,

1969 ,40, 823-832.Zuckerman, M. Dimensions of sensation-

seeking. Journal of Consulting end ClinicalPsychology, 1971,36, 45-52.

Robert PlominAssistant ProfessorInstitute for Behavio~alGeneticsUniversity of ColoradoBoulder, Colorado 80302

Received: September 1 8 , 1 9 7 4Revised: January 8, 1975

extraversion sociability and impulsivity

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