1990 Temperament Behav Inhib Shyness Rothbart-Mauro

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TEMPERAMENT, BEHAVIORAL INHIBITION, AND SHYNESS IN CHILDHOOD

Mary K. Rothbart

and

Jennifer A. Alansky

University of Oregon

Maili ng Address: Departm ent of Psychology

University of Oregon

Eugen e, OR 97403

(503/ 686-4938)



Shyness In Childr en

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Temperament, Behavioral Inhibit ion, and Shyness in Chil dhood

One of t he maj or advances of science in t h is century has been our increased underst anding of t hemolecular basis of t he geneti c code. In the same cent ury, advances in t he neurosciences and in t heemployment of behavioral geneti c t echniques have al lowed psychologist s to consider m ore ser iously t hepossibi l i t y of b i o logical ly-based contr i but i ons t o personal i ty d i sposi t ions. These individual d i f ferences,

cal led t emperament , have proven to be of i ncreasing interest and import ance to st udents of socio-emot ional development. McCal l ( in Goldsmit h et a l . , 1987) has recentl y synthesized current def in i t ions oft emperament as: "re lat ively consist ent, basic d isposi t ions inherent in t he person that under l ie andmodulate t he expression o f act iv i ty , react iv i t y , emot ional i ty , and soc iab i l i ty . Ma jor e lements o ft emperament are present ear ly in l i f e, and those element s are l ikely to be st rongly inf luenced bybiological f actors. As development proceeds, t he expression of t emperament increasingly becomes moreinf l uenced by exper ience and context ." (Goldsmit h et a l . , p. 524) I f we are to accept t he real i t y of ear lytemperamenta l d i f f e rences in act iv i ty , react iv i t y , emot ional i t y , and soc iab i l i ty , we wou ld expect t hem tocontr ibu te s t rongly t o t he development o f soc ial f ear ; indeed, dur ing the per iod o f in fancy, we w ou ldexpect m easures of f ear in social si t uat ions to be strongly ref l ect ive of ear ly t emperament al d isposi t ions.

In th is chapter, we explor e t he const ruct s of behavioral inhib i t ion, shyness, fear and socialanxiety that can be seen to over lap with components of temperament dur ing the per iod of ear lychi ldhood. We t hen relat e these const ruct s t o dimensions of tem perament al var iabi l i t y. Theoretical and

measurement issues in the study of behavioral inhibition and shyness are then discussed, and research ont he ear ly development of t hese disposi t ions is reviewed. We then consider b io logical perspecti ves onbehavioral i nhib i t ion and shyness, including animal m odels and development al behavioral geneticsapproaches. Fina l ly , we a t t empt to re la te ear ly ind iv idua l d i f fe rences in temperament t o thedevelopment of chi ldhood psychopat hology.

Kagan, Reznick and Snidman (1986) define behavioral inhibition as "the tendency to display or nott o display an in i t ia l per iod of inhib i t ion of speech and play, associated wi t h a retreat t o a t arget ofatt achment, when t he chi ld encounter s an unfami l iar or chal lenging event" (p. 54). As t he name of t h isconst ruct suggest s, Kagan et a l . def ine behavioral inhib i t ion st r ict ly in behavioral , not physiologicalt erms, a l though t hey have related i t t o under lying physiology. The const ruct of behavioral inhib i t ion hast o date been appl ied t o tem perament al individual d i f f erences in ear ly chi ldhood, as seen betw een theages of 14 m ont hs and f ive years.

In the const ruct of shyness, on t he ot her hand (Jones, Cheek, & Br iggs, 1986), t he si t uation orcontext is not so general as to include al l novel and chal lenging condi t ions, but is const rained t o includeonly social st imulat ion. Defin i t i ons of shyness also usual ly add an element of f e l t d iscomfor t t o e lement sof behavioral inhi bit ion. Thus, Briggs and Smi t h (1986) define shyness as "discomf ort and inhibit ion in thepresence of ot hers" (p. 629). Buss (1985) also inclu des discomf ort and inhi bit ion in his def init ion ofshyness, and adds t hat shyness may also include w it hdrawal, ret icence, i nhib i t ion of speech and gest ures(simi lar to the defin i t ion of behavioral inhib i t ion given above) and fear, feel ings of vulnerabi l i ty, loweredsel f-esteem and arousal of t he autonomic nervous syst em.

When Buss consider s arousal of t he aut onomi c nervous syst em t o be a def ining aspect of shyness,his defin i t ion includes al l t hree of t he major r esponse syst ems oft en identi f ied in defin i t ions of f ear:"Fear is commonly t hought of as a val id r eaction t o genuine threat t hat involves at least 3 responsesyst ems: a) overt behavioral expressions, b) covert , subj ect i ve f eel ings and t houghts, and c) physiologicalact ivi t y" (Graziano, 1979, p. 805).

When we now consider defin i t ions of social anxiety, we note that important cogni t ive componentsare added to t he element s we have already l ist ed: "This condi t ion (social anxiety) is character i zed byheightened physiological arousal w hen in social si tuat ions, a fear of negative evaluat ion by ot hers, a highl ikel ihood of negative expect at ions regarding the abi l i t y t o inter act w i t h others and in some cases,del iberat e avoidance of t he thr eatening si t uations" (Beidel , Turner, & Dancu, 1985, p. 109).

Reviewing t hese defi n i t ions, we can identi f y f our set s of re lat ed responses t o novel ty and socialchal lenge: t he f i rst is behavioral , including inhibi t ion of speech, gest ures, and motor act ivi t y, andsomet imes wit hdrawal. Behavioral aspects are included in defin i t ions of a l l of these const ruct s. The




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second set includes negative em oti onal reactions. These are not included in t he defin i t ion of behavioralinhib i t ion (al though somet imes they are included in the operational izat ion of behavioral inhib i t ion; seet he discussion of t h is research below), but t hey are included in al l ot her const ruct s. The th ird setincludes physiological arousal , especial ly arousal of t he aut onomic nervous system or i t s sympat heti cbranch, which is again not included in t he expl ic i t def in i t ion of the behavioral inhib i t ion const ruct(al though often st udied along wit h behavioral inhib i t ion) but is included in al l ot her const ruct s. Thefourt h set of responses are cogni t ive, i ncluding expectat ions of negative evaluation f rom ot hers or f romt he sel f , and th is set appears t o be unique to t he social anxiety const ruct . We may thus identi fy a kind ofordinal scale of social inhib i t ion and anxiet y const ruct s based upon t he response syst ems involved, w i t hsocial anxiety seen as the most inclusive, shyness and fear as intermediary and behavioral inhibition ast he most narrow . On t he basis of t he cont ext f or anxiet y, however, f ear and behavioral inhib i t ion aremore general const ruct s than shyness and social anxiet y; bot h f ear and behavioral inhib i t ion includereactions to events going beyond social situations.

We can now consider d im ensions of t emperament t hat m ay be related t o one or more of t hesesets of responses. Relevant t emperament al d imensions would include behavioral inhib i t ion, or ig inal lyobserved by Schaffer (1974) as wariness in infants' behavioral reactions to novelty during the last half oft he f i rst year of l i fe. Whereas a f ive-mont h-old infant approaches novel obj ect s rapidly and impul sively,by eight mont hs of age, t he infant may approach a novel object only slowl y or wi t h some hesi t ancy, ornot at a l l (see also Rothbart , 1988). Another re levant t emperament al d isposi t ion is Thomas and Chess'

(1977) const ruct of approach-wit hdrawal, defined as, " t he nature of t he in i t i a l response to a newst imulus, be i t a new food, new t oy or new person. Approach responses are posi t ive, w hether d i splayedby mood expression (smi l ing, verbal izat ions, et c.) or m otor act ivi t y (swal low ing a new f ood, reaching fora new t oy, act ive play, et c.) . Withdr awal reactions are negative, w hether d isplayed by mood expression(crying, fussing, gr imacing, verbal izat ions, etc.) or motor act ivi ty (moving away, spi t t ing new food out,pushing new t oy away, et c.)" (Thomas & Chess, 1977, p. 21). This const ruct is qui t e simi l ar to t hat offear, as employed by Rothbart (1981; Rothbart & Derryberry, 1981) and Goldsmit h and Campos (1982).The maj or d i f fer ence is t hat Rothbart and Goldsmit h and Campos employ a separate const ruct for smi l ingand laughter or j oy, rat her t han including t h is d im ension wit h the f ear const ruct , as do Thomas andChess.

To the ext ent t hat t he const ruct s of behavioral inhib i t ion, shyness, f ear and social anxiety alsoinclude f e l t or expressed negat ive aff ect, we w ould expect t he chi ld 's general d istress proneness ornegative em oti onal i ty t o be relat ed t o t hem (Bat es, 1987, in press; Buss & Plomin, 1984; Rothbart , i n

press a). Final ly, w e might expect t hat individual d i f f erences in att enti onal control ( t he shi f t ing andfocusing of att enti on) would aff ect bot h t he chi ld 's soothabi l i t y when exper iencing social d ist ress and themore cogn i t ive aspects of anxie ty , bu t w e wou ld not expect i t to m atch t he construct s d i rect ly .Temperamenta l ind iv idual d i f f e rences in f lex ib i l i t y and contro l o f a t t en t ion are impor tant bo th in t he i rinf l uence upon recovery from negative em otion (soot habi l i t y) in infancy (Rothbart , in pr ess a), and int heir re lat ionship t o the individual 's abi l i t y t o shi f t away from a negative f ocus in adolescence andadulthood (Derryberry & Rot hbart, in press; Mathew s and Macleod, 1986). These t emperament alcharacter ist ics may be seen t o be bio logical ly based, and at l east for t he dimensions of negat iveemot ional i ty and behavioral inhib i t i on, t hey show considerable longi tudinal stabi l i t y once they haveappeared in development (Buss & Plomin, 1984; Rothbart, in press a).

Given t h is degree of over lap across dimensions of t emperament and social f earfu lness, we nowdiscuss the ear ly development of behavioral inhib i t i on and shyness, assuming t hat t hese const i t ut e ear ly

assessment s of t emperament as wel l as social fear. We wi l l not d i scuss t he development of negativeemot ional i ty and att enti on direct l y, because one of us has reviewed t hem in detai l e l sewhere (Rothbart ,in press).

Behavioral Inhibit ionThe most ext ensive research done on behavioral inhib i t ion in young chi ldren has been the

longi tudinal w ork begun by Cynthi a Garcia-Col l w i t h 21-month i nfant s and conti nued by Kagan and hiscol leagues. Since t h is work const i t ut es t he maj or corpus of r esearch avai lable on behavioral inhib i t ion,




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we review i t here in det ai l . This detai led exposi t ion w i l l a lso al low us to discuss di f ferences in Kagan et.a l 's use of t he behavioral inhib i t ion const ruct as t he chi ld grows older.

In Garcia-Col l et a l . 's (1984) in i t ia l report , ext reme groups of 21-mont h-old chi ldren on adimension of inhib i t ion to unfami l iar i t y were identi f ied. A large sample of 305 infant s was f i r st screenedby asking the chi l dren's mot hers to descr ibe t heir chi ld 's reaction in e ight sett ings (meet ing unfami l i archi ldren, visi t ing t he doctor, et c.) . Chi ldren report ed as showing wit hdrawal to four or more of these

si t uations were considered as candidates for f a l l ing into t he behavioral ly inhib i t ed category; chi ldren w hoapproached in seven or m ore si tuat ions were considered as candidates for being behavioral ly uninhibi t ed.These inhibi ted and uninhibi t ed chi ldren, as seen by their m others, wer e then brought int o the laborator yfor f ur t her assessment as t hey engaged in free play, separati on from t he mot her, int eract i on wit h ast range adul t and exposure t o a novel toy (a robot) . Indices of inhib i t ion in the laboratory includedwit hdrawal, cl inging t o the m other, crying, inhib i t ion of p lay, f acia l and vocal expressions of d istress, andextended lat ency to approach a novel person or object . Infants who displayed nine or more of t hesebehaviors were cl assi f i ed as behavioral ly inhib i t ed; t hose who displayed t wo or f ewer as uninhibi t ed. Theinhibi t ed group included 33 chi ldren (11% of t he or ig inal sample); t he uninhibi t ed group included 38chi ldren (12% of t he or ig inal sample). Heart and respirat ion rate of each chi ld was also monit ored whi let he chi ld w as exposed t o a ser ies of fam i l iar and unf ami l iar sl ides, l inguist ic phrases and environmentalsounds. Inhibi ted chi ldren by t he behavioral cr i t er ion were f ound to have higher and more st able heartrates than their uninhibi t ed peers.

These ext reme groups of inf ants were next observed at a l i t t le under 3 years (31 months) of age(Kagan et a l . , 1984). At 31 months, the chi ldren w ere observed at home whi l e engaged in free play, inplay wit h an unfami l iar peer and whi le l ist ening t o a st ory accompanied by sl ides. Most of t he var iablesscored for t he home and peer episodes involved t he lat ency and frequency of approaches to a novelperson or obj ect. A moderat e correlat ion was found betw een the infant s' behavior in t he laboratory at 21mont hs and their behavior at home (r = .39) and wit h an unfami l iar peer (r = .66) at 31 mont hs. Kagan etal . reported some stabi l i ty over t ime for inhib i t ion, especial ly in predict ing chi ldren's behavior wi th theunfami l iar peer, but t h is f indi ng should be interpr et ed wit h caution, because the sample had beenreduced to only 21 chi ldren for t he peer inter act ion measure. No relat ion between inhibi t ion and heartrate w as found at 31 months, and no st abi l i t y across t ime w as found for heart rat e. On t he basis of t hesedata, Kagan et a l . (1984) argued t hat bet ween t he ages of t wo and f our years, t he chi ld 's reaction t o anunfami l iar peer becomes a more appropr iate index of behavioral inhib i t ion t han exposure t o unfami l iart oys, set t ings or adul ts. At least as operational ized, t hen, t he behavioral inhib i t i on const ruct becomes

const rained by social sett ing t o become m ore l ik e a shyness const ruct .

The longitudinal sample was next assessed when they were four years old (Kagan et al., 1984).Kagan et a l . (1986) argue t hat betw een four and six years, behavioral inhib i t ion can be best measured in avar iety of sett ings: inhib i t ed chi ldren are expect ed to continue to be cautious around others and quick tore t rea t f rom unfami l ia r se t t ings. In add i t ion , however , t hey may become concerned wi t h o thers'evaluat ions o f t hem, w h ich might resu l t in re luctance to a t t empt d i f f i cu l t cogni t ive t asks or a tendency todirect f requent g lances at individuals in the posi t ion of evaluati ng t he chi ld. Not e that by age four, t heassessment s are t hus movi ng tow ard assessment s of social evaluat ion anxiet y. At f our years, Kagan et al .asked the chi ldr en and t heir parents to make tw o visi t s t o the laboratory and t o part ic ipat e in a numberof cogni t ive t asks whi l e heart rat e was monitored. Assessment now stressed chi ldren's reactions tocogni t ively chal lenging or d i f f icul t st im ul i , and chi ldren w ere observed mat ching fami l iar f i gures,engaging in m emory t asks, const ruct ing a car f rom blocks, and t aking several subt est s of a comm only used

IQ t est . Tasks were chosen because they w ere expected t o chal lenge most of t he chi ldren, and codingincluded number of g lances t o the mot her and examiner, number of t imes the chi ld fa i led t o answer aquestion and gross mot or movem ent s. Child ren w ere also exposed t o a st ory accompanie d by sl id es abouta fearf u l and f ear less chi ld, and t o a ser ies of sl ides depict ing bot h act i ve and passive scenes, wi t h t heamount of t ime spent looking at act ive vs. p assive st imul i was recorded.

Peer play episodes used were similar to earl ier assessments, with measures of latency toapproach ob ject s or t he o ther ch i ld , p rox imi t y t o the m other and f requency o f st a r ing a t t he o ther ch i ldcombined to form an inhibi t ion index and an uninhibi ted index. Dur ing the cogni t ive tasks, chi ldren in t heinhibi t ed group had more st able and higher heart r ates, and showed few er gross mot or movement s. They




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also looked more frequent ly at t he examiner and refused to answer m ore quest ions t han their uninhibi t edpeers (Kagan et a l . , 1984). The inhibi t ed group also had a higher f requency of f ears, n ight mares,sleeplessness and const ipati on, according t o mat ernal int erview. This group looked at passive pict ureslonger and ta lked about them more than for act ive pictures.

It should be noted t hat a l t hough Kagan et a l . (1984) might have expect ed t he behavioral lyinhibi t ed chi ldren to have been especial ly concerned about adul t evaluat ion, t here was l i t t le evidence of

t h is. St abi l i t y of inhib i t ion classi f i cat ion bet ween 21 months and four years was most st rong i f the inf anthad a st eady heart rat e and had been classi f ied as being inhibi ted at 21 months. I f t he chi ld wasclassi f i ed as being inhibi ted at 21 months, but d id not have a st eady heart rate, t hen the l i kel ihood oft hem being classi f i ed as inhibi t ed at four years was smal ler .

The most r ecent f o l low-up of t h is longi tudinal sample was done when the chi ldren wer e 5-1/ 2years old (Reznick et a l . , 1986). As at t he four year assessment , heart and respirat ion rates weremonitored dur ing di f f icul t cogni t ive tasks, subjects played with an unfami l iar peer, and there was amat ernal interview . In addi t ion, pupi l d i lat ion dur ing select ed cogni t ive tasks, wi l l ingness t o performphysically r isky behaviors such as walking a balance beam and climbing bars and two school observationswere added t o th i s phase of assessment . In school observations, amount and t ype of int eract ion of t hesubj ect w i t h other chi ldr en in the classroom wer e coded.

Variables from peer play, lab, school observations, r isk avoidance episodes and number of looks at

t he examiner in t he cogni t ive t asks were combi ned to f orm an inhibi t ion index used in some of t heanalyses. Reznick et a l . (1986) found st abi l i t y for inhib i t ion classi f i cat ion in t hat 78% of t hose chi ldrenclassi f i ed as inhibi t ed at 21 mont hs remained in t hat cat egory at age f ive, even though a number of qui t edi f f erent assessment s of behavioral inhib i t i on were used at t he latt er t ime.

The inhibi t ed group as det ermined at 21 months also had more st able heart rat es at 5-1/ 2 yearson al l episodes in t he laboratory and had increased pupi l d i lat ion. Pupi l d i lat ion was unrelated t o currentinh ib i t ion or ear l ie r hear t ra t e stab i l i t y , however . The consistent re la t ion between hear t ra te stab i l i t yand inhibi t ion was also seen as ref lect ing consist ency in t he struct ure of behavioral i nhib i t ion across age.

In an att empt t o repl icat e Kagan et a l . 's f indings fr om t he longi t udinal sample, Reznick et a l . ( inpress) st udied a sample of inf ants who did not r epresent ext remes of inhib i t ion, but const i t uted anorm at ive sampl e. Infant s in t his sampl e were assessed at 14, 20 and 32 mont hs of age. At 14 and 20mont hs, inf ants part ic ipated in a number of laboratory episodes, six of which f ocused on inhibi t i on.

Infants at f i rst p layed in the laboratory, fo l l owed by t he exper iment er hanging a dog mask in the cornerof t he room (used only at 14 months). Lat er, a st ranger enter ed the room and eventual ly t r ied t o hand at oy to the chi ld. The f inal tw o episodes involved an alarm clock being set of f in t he room whi le t he chi ldwas playing and t he chi ld being shown a large t oy robot.

At 14 and 20 months infant s were scored on behaviors lat er grouped int o t wo cat egor ies,approach/ wi t hdrawal and negat ive a f f ect (cry or f re t ) . The negat ive a f fect var iab le was found to beposi t ively correlated with inhibi t ion at 14 months and 20 months, but i t d id not separately predictinhib i t ion at 20 mont hs. In addi t ion, a composi te index of inhib i t i on and negative aff ect w as no moreaccura te a t p red ic t ing fu ture inh ib i t ion t han the inh ib i t ion index a lone, and t he negat ive a f fectcomponent w as t herefore dr opped from t he analysis. Play sessions at 32 mont hs included 3 chi ldren (oneinhibi t ed, one uninhibi ted, one nei t her, as det ermined at t he ear l ier ages) of t he same gender whoplayed together for 30 minut es. Lat ency to leave t he parent , t ouch a toy, enter a plast ic tunnel andapproach another chi ld, fr equency of approaching another chi ld, t aking an object away from a chi ld,

enter ing the tunnel , and enter ing another chi ld 's terr i tory were coded. In addi t ion, durat ion of star ing ata chi ld and proximit y to t he parent wer e coded as wel l as t he tot al amount of t ime spent i n socialin teract ion wi t h anot her ch i ld .

Having el im inated distress fr om t he operational izat ion of t he const ruct , Reznick et a l . def ineinhibi t ion as "emphasizing vulnerabi l i t y t o the uncert a inty caused by unfami l i ar events that cannot beassimi l ated easi ly", and they st ress t hat t he term represent s "the const ruct of int erest , rat her thanshyness, fearf u lness or t imidi t y." As in Kagan's work, Reznick, et . a l bel ieve t hat inhib i t i on can best beshown by one set of behaviors at one age and another set of b ehaviors at anot her age. Thus at 14mont hs, i nhib i t ion may be best demonst rat ed by general fear i t ems such as exposing the chi ld t o a dog




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mask and at 32 mont hs by placing t he chi ld in a social sett ing wit h an unfami l iar peer. The el ic i t ingst imul i (and the consequent behavior) change over development .

As wit h t he previous work, approximat ely 15% of t h is sample could be classi f i ed as beinginhibi t ed. The var iables scored as inhibi t ed at 14 and 20 months (proximi t y to parent, lat ency to touchtoy, etc.) posed a problem for determining an uninhibi ted group for 32 months, however, in thatfr equency dist r ibut ions did not a l low f or t h is classi f i cat ion. This problem w as solved by using var iables

( t im e p lay ing wi th the peer , approaches to t he peer , e tc . ) t ha t had a more normal d ist r i bu t ion than t imein proximit y to parent or latency to touch a t oy. The measure thus became one more of uninhibi t edbehavior than of inhib i t ion.

In addi t ion to explor ing the relat ionship between inhibi t ion and other aspects of temperament,t h is st udy sought t o repl icate Kagan et a l . 's f indings on the st abi l i t y of inhib i t ion. When data f rom onlyt he tw o extrem e groups were exami ned, t he correlat i ons across age for i nhib i t ion indexes were . 68betw een 14 and 20 mont hs, . 71 between 20 and 32 mont hs, and .66 bet ween 14 and 32 months. Thest abi l i t y correlat ions for the ent i re sample ranged fr om .06 t o .39, and Reznick et. a l argue that t here isgreat er st abi l i t y i f the chi ld is more extr eme on t he inhibi t ion measure. As a repl icat ion, i t i s import antt o note t hat t he episodes in t h is st udy were not ident ical t o those used by Kagan and that t he inhibi t ionindexes di f fered betw een ages of assessment and betw een st udies. Chi ldren i n ext reme groups were alsomore l ikely t o drop out of t he sample, t hus reducing the sample size as wel l as possibly b iasing t hecomposi t ion of t he groups.

Issues in the Assessment of Behavioral InhibitionTwo im port ant issues in t he assessment of behavioral inhib i t ion are, f i rst, whet her d istress is to

be included in the const ruct and second, whet her behavioral inhib i t ion ref ers t o only a smal l , extr emegroup of chi ldr en (categor ical assessment ) , or t o a dim ension on w hich a general sample of chi ldren canbe ordered (dim ensional assessment ). The dist ress question is im port ant , because it s resolut ion hasimpl i cat ions for w hether behavioral inhib i t ion can be seen to be simi lar t o the const ruct s of f ear andshyness, w hich includ e dist ress. This issue may in part b e relat ed to m et hodological issues. Shyness isoften assessed in adults (Cheek & Buss, 1981), and adults can be asked whether they experience feelingsof d iscomfort when int roduced to strangers. In an infant, fr ank dist ress expressions in t he presence of anovel person or obj ect can also be coded, and distr ess oft en accompanies the chi ld 's wi t hdrawal f rom t heperson or inhib i t i on of approach (Sroufe, 1979). By the t ime t he chi ld is 32 mont hs old, how ever, t here

may be l i t t le d irect expression of d ist ress, w hi le at t he same t i me t he chi ld may be feel ing discomf ortt hat w e are unable t o measure. We cannot assess t hese int ernal st ates in the t oddler because to dat e,sel f- r eport on emot ion is not a viable assessment t echnique at t h is age.

In our research, we have developed a caregiver report measure, the Children's BehaviorQuestionnaire, which assesses shyness as well as other temperamental characteristics, for children aget hree t o seven years (Rot hbart , 1988). Our shyness scale incl udes item s assessing childr en's lat ency t oapproach other people and their apparent comfort or d iscomfort in si tuations where they might need toapproach ot hers. For t h is scale, i t ems assessing latency t o approach were posi t ively correlat ed wit hi t ems deal ing wit h discomf ort . Simi lar ly, i n developing t he Infant Behavior Quest ionnaire ( IBQ; Rothbart ,1981) Fear scale, anot her caregiver report measure, w e had or ig inal ly at t empt ed t o develop t wo scales,one assessing chi ldren's negative aff ect t o novel t y or chal lenge, t he ot her, chi ldren's latency t o approachnovel persons or obj ect s. We could not devel op enough it ems to assess t hese dim ensions separat ely w it hacceptable internal re l iabi l i ty, but the two classes of i tems were posi t ively re lated to each other and,

once we combined t hem, i t was possible t o develop a scale wi t h good inter nal re l iabi l i t y (Rothbart , 1981).Again, the two sets of i tems, latency and negative affect, were posi t ively correlated.

Thus, in t he Infant Behavior Quest ionnaire, m ot hers' observations of f rank distress were posi t ivelyrelat ed t o t he chi ld 's lat ency to approach; in t he Chi ldren's Behavior Quest ionnaire, m others' j udgments oft heir chi ld 's d iscomfor t in novel social si t uat ions were also posi t ively re lat ed t o latency t o approach.Final ly, for a smal l sample of longi tudinal subject s assessed w it h t he IBQ dur ing infancy and fo l low ed upat age seven, ear ly mot her rat ings of f ear at 6, 10 and 13 mont hs (but not at 3 months) were signi f icantl yposi t ively correlat ed wit h mot hers' lat er rat i ngs of t heir shyness. In our work, t hen, as wel l as in otherresearch assessing f ear in h umans (Goldsmi t h and Campos, 1982) and in non-hum an pri mat es (Higley &




pg 7

Suomi, in press), i nhib i t ion and dist ress can be combined t o form a single constr uct. This view is, ofcourse, qui t e di f f erent f rom t he posi t ion taken by Reznick et a l . ( in press), w ho would wish tocharacter ize behavioral inhib i t ion in term s of int erest rat her than as a fear-re lat ed dimension.Nevert heless, Reznick et a l . 's own f indings for infant s at bot h 14 and 20 months were t hat inhib i t ion anddist ress were posi t ively correl ated.

Anot her approach t o met hodological problem s in assessing discomf ort in t oddlers might be t o use

psychophysiological measures such as Galvanic Skin Response, whi ch have be en associat ed w it h rat ings offear (Buck, 1988), concurrently w i t h measures of behavioral inhib i t ion. In th is regard, Kagan et a l . (1987)have already found t hat m easures of sympathet ic nervous syst em f uncti on, such as high heart rat e, w hichmight be t aken as indicants of f ear react ions, are posi t ively re lated t o inhibi t ion. We wi l l see below thatin studies wit h rhesus monkeys using a behavioral inhib i t ion paradigm, t he const ruct has al ter nativelybeen called t im idit y or anxiet y (Higley & Suomi , in press). Researchers using an animal model t hus alsoinc lude negat ive a f fect wi t h in the construct under s tudy. We wou ld argue t ha t dura t ion o f in te rest maybe a temperament al d imension wort h st udying, but t hat research resul t s on the behavioral inhib i t ionconstruct suggest that i t is related to distress and should be seen as having close ties to constructs ofshyness and social fear.

A second issue in t he assessment of behavioral inhib i t ion has t o do wi t h w hether t he const ruct isonly appl icable to a group of 10-15% of t he chi ldren at t he tw o extr emes of t he measure (categor icalassessment ) , or w hether t he dimension can be appl ied t o the compl et e range of chi ldr en. In Thomas andChess' (1977) Approach-Withdrawal construct and our (Rothbart & Derryberry, 1981) and Goldsmith andCampos' (1982) Fear dim ension, w e would expect t he const ruct t o apply t o t he fu l l range of i nfant s andyoung chi ldren. One kind of evidence that w ould support t he use of behavioral cat egor ies would beevidence of d istr ibut ions that are bi- or tr i -modal, wi th extreme groups of chi ldren forming separatedist r ibut ions at t he extrem es of t he populat ion. We have not seen such evidence put f orward, and sinceour own dat a do not suggest t he exist ence of separate diagnost ic groups, w e feel m ore comfor t ableapplying t he const ruct t o the general populat ion of chi ldren.

Shyne ss and Social Anxiet y

Arnold Buss (1980, 1985, 1986) has made an im port ant cont r ibut ion t o our underst anding of t hedevelopment of shyness and behavioral inhib i t ion. In h is t heory of t he development of shyness, he posi t st wo kind s of shyness: one is seen to devel op early, and t his he calls fear ful shyness. The second kind isseen t o be lat er-de veloping and is call ed self -conscious shyness. Early- developi ng shyness woul d be

simi l ar to t he behavioral inhib i t ion descr ibed above, assuming, however, t hat w e can conti nue to includeit s distr ess compone nt . In Buss' t heory, t his fear ful shyness is seen to devel op during the last half of t hefi r st year, t o wane over t ime f or most young chi ldren, but for some chi ldren to persist . Buss argues t hatlater in development , f earfu l shyness is demonst rat ed not in overt d ist ress, but "by the inhibi t ion ofspeech and behavior int eract ions t hat ar e t ypical of adult shyness" (Buss, 1985, p. 40). Buss also arguest hat f earfu l shyness wi l l later become a kind of social anxiety where t he person becomes dist ressed atbeing evaluated w hen meet ing others.

Buss then describes lat er-deve loping shyness, called self -conscious shyness, as beingcharacter ized by sensi t iv i t y, inhib i t ion or d isorganizat ion of social behavior when t he individual is exposedt o the scrut iny of ot hers. Buss suggest s t hat t his kind of shyness emer ges around t he age of f ive years,when m others begin to r egular ly r eport inst ances of social embarrassment in t heir chi ldr en (Buss, Iscoe, &Buss, 1979). He suggest s t hat t his self -conscious shyness may result f rom t he associat ion bet wee n being

scrut in ized and being cr i t ic ized or r i d iculed, and by a person's feel ings of bei ng di f f erent or conspicuousby reason of race, gender or ot her charact eristi cs. He suggest s t hat self- conscious shyness woul d beespecial ly l ikely t o be el ic i ted in f ormal context s where t he person is int eract ing wit h a high st atusindividual .

Conceptual ly, we have some di f f i cul t y in d ist inguishing the social anxiety aspect of ear ly-appearing (fear fu l) anxiet y as described by Buss fr om his later -appearing self -conscious shyness. It w ouldbe conceptua l ly simpler , we t h ink, t o inc lude soc ial anx ie ty re la ted t o evaluat ion wi t h t he constr uct o fself -conscious rat her t han fearf ul shyness, and t o see self -conscious shyness (incl uding evaluat ion




pg 8

apprehension) as developing later t han infancy, at a t i me w hen the chi l d has become sensi t ive t o t heevaluations of others.

Buss fur t her suggest s t hat self -conscious shyness develop s when t he chil d has at t ained an"advanced, cognit ive" self (Buss, 1985, p. 43). Research in social cognit ion suggests t hat chi ldr en'sconcept of sel f as endur ing over t ime and across si t uations and as including inherent personal qual i t ies(personality traits) does not develop in our society unti l ages seven to nine (Rholes & Ruble, 1984;

Rotenberg, 1982). Thus t he kind of sel f-consciousness seen in chi ldren at age f i ve may be relat ed t o theirsensi t iv i t y to cr i t ic ism, but i t a lso may not requir e a high level of cogni t ive sophist icat ion in t h inkingabout t he sel f . Nevert heless, w hen th is sophist icat i on develops, w e would expect t hat chi ldren wouldbecome increasingly vulnerable to negat ive feel ings relat ed to t heir sel f-w ort h, and t h is appears t o be thecase (Harter, 1983).

For our underst anding of t he relat ion betw een tem perament and social anxiety, Buss' t wovarieties of shyness are of special interest because the first, fearful shyness, would be seen ast emperament al ly based. Of the t wo var iet ies of shyness, i t is re lat ively ear ly appear ing, and does notseem t o have been inf luenced by t he experien ce of crit icism, as does self -conscious shyness. It is alsovery similar to Thomas and Chess' (1977) approach-withdrawal dimension and our (Rothbart, 1981) andGoldsmi t h and Campos' (1984) dimension of fear . The lat er-deve lopin g, self -conscious shyness asdescr ibed by Buss would be seen more as an aspect of personal i t y t han tem perament . I t i s presumablystrongly determined by exper ience, and i t is re lated to a cogni t ive structure, the representat ion of sel f ,that would be seen to go beyond the domain of temperamental d i f ferences.

A retr ospecti ve st udy wher e col lege st udents' sel f - report of t heir curr ent and previous shynesswas invest igat ed has provided some support for Buss' theory (Cheek, Carpent ier i , Smit h, Rierdan, & Koff ,1986). St udents reported whet her they now considered t hemselves shy, and whet her t here had been aprevious t i me in their l ives when t hey considered t hemselves t o be shy. Fort y- t hree percent of t hesubj ect s repor t ed curr ent shyness, 41% repor t ed previ ous but not cu rren t shyness, and 16% repor t ed t heyhad never considered t hemselves shy. Among t he current ly shy st udents, 45% report ed t hey f i r st becameshy bef ore t he age of 6, whi l e among t he current ly not shy st udents, only 21% report ed ear ly shyness.Cheek et al. take this finding as support for Buss' theory, suggesting that early appearing shyness, at leastas indicated by t h is ret rospecti ve report , is more development al ly st able as might be expected of at emperament al ly-re lat ed dim ension t han later appear ing shyness.

To the ext ent t hat f earfu l shyness is t emperament al ly based, w e also need to consider t he

specif icit y of shyness (and behavioral inhi bit ion) t o social as opposed t o non-social stim uli. Buss (1986)argues t hat fearf u l shyness is d i f f erent f rom ot her fears in that i t i s a social anxiet y. To what ext ent isfear of people independent of ot her fears or from a general tem perament al d imension of fearf u lness?

During chi ldhood, w e have addressed t he quest ion of t he relat ionship bet ween social and non-social f ear b y assessing bot h shyness and non-social, general f earf ulness in t he Childr en's BehaviorQuest ionnaire, a parent report inst rument (Rothbart , 1988). In a sample of 235 subj ects age 3-7 years,including a large group of chi ldren who w ere t wins, we have found a low but signi f icant corr elat i on (r =.18) betw een the t wo scales. For a sample of 80 singleton 6-7 year o lds t he correlat ion bet ween t hescales was moderate in size (r = .36). We have also developed a sel f- r eport t emperament quest ionnairewhi ch we have used wi t h a sampl e of over 90 early adolescent s (Capaldi , 1988). This measure alsoassesses shyness in a scale separate f rom gener al f earf ulness. Again, t he t wo scales are positi velycorrelat ed (r = .48). This ear ly adolescence scale is of special int erest , because i t a l lowed us to gather

sel f- r eports from subj ects about t heir own f e l t shyness, and we also administ ered a highly abbreviat edversion of t he adolescent shyness scale and adapt ed i t t o parent 's independent report . This a l lowed us tocompare the t wo scale scores, parent -report and sel f- r eport , w i t h one another. The tw o scales indeedproved to be posi t ively correlat ed wit h each other (r = .46).

In a fur t her development of our adul t t emperament measure (Derryberry & Rothbart , in press),we have also separated out shyness from general non-social fear items, and, as in parents' reports foryoung chi ldren and ear ly adolescents' sel f- r eport , have found t hem t o be posi t ively correlat ed for asampl e of 90 college st udent s. Thus, in general, our r esult s suggest t hat shyness and non-socialfearf u lness are posi t ively re lat ed, and t hat t emperament al ly, shyness may be seen as one manifestat i on




pg 9

of a general t endency toward f earfu lness. The most useful w ay to t h ink about social fear or shynessmight be to say t hat a l t hough we m ight t h ink about i t as being related t o general fear, i t is a lso possibleto assess it separately, depending on the research questions we are interested in addressing (Rothbart, inpress c).

Unlike the constructs of behavioral inhibition, shyness and social fear, social anxiety and Buss'later developing sel f-conscious shyness wit h t heir cogni t ive and evaluat ive content may be said t o be non-

t emperament al . Thus, a l though a predisposi t ion to negative emot ional i ty may lead a chi ld to frequent lyexper ience negative af fect in t he presence of ot hers and t hus t o develop negative expect ancies aboutothers and about t he chi ld 's abi l i t y to deal wi t h them , i t i s a lso possible t hat a chi ld t emperament al ly lowin suscepti b i l i t y t o d istress may develop negative ex pectancies and sel f evaluations. These may resul tfr om frequent negative exper iences when others express cr i t ic ism or d issatisfact ion wit h the chi ld. I t isalso possible t hat chi ldr en who have a great deal of d i f f icul t y shi f t ing at t ention away fr om a negativefocus may be predisposed t oward anxiety. In th is case, individual d i f fere nces in t he focusing and shi f t ingof attention would make a contr ibut ion to chi ldren's susceptib i l i ty to anxiety.

Biological Models for Behavioral InhibitionEver since the pi oneer ing work of Calvin Hal l (1936), i t has been suggest ed t hat a rat 's ambulat ory

activi t y and defecat ion in an open (novel) f ie l d is a measure of t hat animal 's reactivi t y or emotional i t y.King and Appelbaum (1973) have determi ned, however, t hat t he measures of rat emot ional i ty t hat showdecrement s over t im e (as would be expected w hen the animal becomes more f ami l iar ized t o the set t ingand hence less fearf u l of i t s novel ty or str angeness) are not general act ivi t y and defecati on, but inst eadinc lude t im e to emerge f rom t he home cage and t im e t o t raverse the runway to t he f ie ld . Thesemeasures show strong simi l ar i t y t o t he non-dist ress aspects of t he const ruct of behavioral inhib i t ion.

Behavioral inhibition has also been studied using the rhesus monkey as a model, althoughsomet imes the pr ocess st udied has been cal led anxiety (Suomi, 1984, 1986), t imidi t y or r eactivi t y (Higley& Suomi, in press). Measures of behavioral inhib i t ion, t imidi t y or react ivi t y in r hesus monkeys assessfearf u lness or anxiety in novel or chal lenging si t uations and behavioral wi t hdrawal in social int eract ion.Speci f ic m easures have included maintenance of proximi t y t o an at t achment obj ect (Suomi, 1983),la tency to approach st im u l i in a nove l si tua t ion , in i t ia t ion o f in t e ract ion w i th unfami l ia r ind ividua ls(Thompson, Higley, Byrne, Scanlan & Suomi, 1986), and assessments of anxiety (oral behaviors, hand-wri nging and sel f-clasping, im mobi l i t y, huddl ing and distress vocal izat i ons) t o social separati on (Mineka,

Suomi , & DeLizio, 1981; Suomi , Kraemer , Baysinger & DeLizio, 1981). These measures correspond t o theassessment s of behavioral inhib i t ion in human chi ldren, wi t h t he exception of t he anxious behaviors tosocial separation.

Suomi and his associates, l ike Kagan et al. (1986), have suggested that the indicators of anxiety inrhesus monkeys tend t o change over age. For the monk eys, signs of anxiet y during separat ion are theindicators most f requentl y found in infancy (Higley & Suomi, i n press). Lat er, behavioral wi t hdrawal,f l ight and immobi l i t y in novel or chal lenging si t uations wi l l be seen relat ively mor e oft en in h ighlyreactive monkeys. Thompson, et a l . (1986) found t hat rat ings of f earfu lness and consolabi l i t y whenexposed to a novel room dur ing t he f i rst m onth predict ed reactions t o unfami l iar peers and object s in anovel room at four m onths, wi t h monkeys who wer e more reactive at t he younger age lat er showinglonger latency to explore the room and objects in i t , a longer t ime in close proximity to their surrogatemot her and more t im e observing the peer monkey explor ing t he room.

Neonatal ratings of fearfulness and consolabil i ty also predicted ratings of despair during a socialseparation w hen t he animals were six mont hs old (Becker, Suomi, Marra, Higley & Brogan, 1984), andHigley and Suomi (in press) have suggested that there may also be a correlation in humans betweenbehavioral inhib i t ion and suscepti b i l i t y t o depressive react ions. Higley (1985) has also report ed t hatmeasures of fearf u lness and anxiety in t he home cage (oral behaviors and clasping, imm obi l i t y) showedst abi l i t y fr om mont h 9 (rhesus monkey infancy) t o mont h 18 (chi ldhood) to m onth 30 (ear ly adolescence),and found a posi t ive correlat ion bet ween signs of anxiet y in inf ancy and behaviors indicat ive of despair atadolescence.




pg 10

Just as rodents have been bred for reactivi t y in open f ie ld t ests (Bl izard, 1981), Suomi and hiscolleagues have also bred rhesus monke ys high and low i n behavioral inhibi t ion. In one st udy, t hese highand low inhibi t ed animals were t hen cross-fostered t o mot hers high and low in mat ernal ski l ls. Whereast here were no main eff ects or interact ions for rear ing condi t ions of t he monkeys, t he animals who hadbeen bred for behavioral inhib i t ion later showed less explorat i on and more stereot ypic movement in aseparation si tuation, more ventral-ventral proximity when placed in a l iv ing uni t wi th peers, and moreini t iat i on of aggression t o ot her group member s (Champoux & Suomi, 1986; Suomi, Champoux, Higley,Scanlan, & Schneider , 1986).

Al though evidence for rear ing eff ects was not f ound for t h is h ighly select ed sample, t here is alsosuggest ive evidence t hat r ear ing condi t ions may inf luence behavioral inhib i t ion in inf ant rhesus monkeys(Higley & Suomi, in press). Peer ra ised monkeys, w ho spent t heir f i rst mont h in a nursery wi t h or wi t houta surrogate mot her and who wer e t hen housed in groups of f our infant s wi t hout adul t s, showed high levelsof inhib i t ion in contr ast w i t h mother-r eared infant s. Thus, at a t ime when monkeys raised wit h motherswere showing much less of t heir ear ly vent ral cl inging, peer m onkeys continued t o show ext ended cl inging(Chamove, Rosenblum, & Har low, 1973; Har low, 1969, Hirsch, Higley & Suomi, 1986), of t en continuingt his behavior into t heir second and th ird years (Higley, 1985). These behaviors are especial ly l ikely t ooccur wi t h t he appearance of a stranger or t he occurrence of novel sounds in t he home cage. Higley,Danner and Hirsch (1988) have also found that in an adaptation of Ainsworth's strange situation to rhesusmonkeys, peer-reared inf ants are more l ikel y to rem ain close to a favor i t e peer and t o explore the

environment and int eract w i t h the stranger less.Thus t he rhesus monkey st udies of behavioral inhib i t ion also provide evidence f or a bio l ogical ly-

based predisposi t ion t hat shows considerable stabi l i t y across t he l i f espan. In addi t ion, correlat ionsbetw een behavioral inhib i t ion and separation anxiet y and lat er suscepti b i l i t y t o depression suggest t hepossibi l i t y t hat t h is var iable may also be related t o depression in humans as wel l .

Behavioral Genetics ApproachesTrai ts re lat ed t o shyness, such as sociabi l i t y, extr aversion, and em oti onal i ty, have been st udied

extensive ly in t he behavior genet ics l i te ra ture , wi t h modera te her i t ab i l i ty f o r t hese fact ors foundt hroughout t he l i f espan (see review s in Buss & Plomin , 1984; Plom in & Daniels, 1986). However , shynessi t sel f has received less att enti on in behavior genetics st udies. The few studies that have examined agenet ic component of shyness have var ied great ly in t heir def in i t ion of shyness, and many rely on

quest ionnaires wit h very f ew i t ems, or quest ionnaires designed to measure const ruct s ot her t han shynessas t heir source of data. In the maj or i t y of t win studies conducted, corr elat ions for shyness rat ingsbetw een monozygoti c tw ins are consist entl y h igher than bet ween dizygoti c tw ins. These st udies t ypical lyemploy parent report quest ionnaires or int erviews, of t en using the EASI sociabi l i t y scale. As t he chi ldapproaches adolescence, the self-report Cattell 16 PF Scale is most often used.

The most extensive st udy in t h is l i terat ure is the Colorado Adopt ion Proj ect (CAP) carr ied out byPlom in and his associat es (Daniel s & Plomin, 1985; Plom in & DeFries, 1985)). The sampl e included over200 infant s betw een the ages of 12 and 24 mont hs, f rom bot h adopt ive and nonadoptive fami l ies. Infantshyness was assessed by a 5-it em sociabil i t y scale on t he Colorado Childhood Tem peram ent Invent ory.The sociabi l i t y scale on t he Colorado Chi ldhood Temperament Invent ory consist s of i t ems ranging fromgeneral sociabi l i t y (chi ld is very sociable, makes fr iends easi ly, is fr iendly wi t h st rangers) to b ehavioralinhib i t ion ( takes a long t im e to w arm up t o st rangers) and shyness (chi ld t ends t o be shy). In addi t ion,each parent fi l led out the Cattell 16 PF Scale including a shyness factor and a second-order extraversion

fact or, as wel l as t he sociabi l i t y scale f rom t he EASI quest ionnaire on bot h t hemselves and t heir spouse.Finally, the Family Environment Scale (FES) and Home Observation for Measurement of the Environment(HOME) w ere used t o assess the inf ant 's home envi ronm ent .

Resul t s fr om t his proj ect i ndicated t hat bot h genet ic and social izat ion var iables played a role int he origin of inf ant shyness. Perhaps t he most excit ing result found by t he CAP was a signif icantcorrelation between biological mothers' shyness and sociabil i ty and their infants' shyness at 24 months, acorrelat ion found for both adopt ive and nonadoptive fami l ies. The f indi ng for adoptive fam i l ies isespecial ly impr essive since the bio logical parent 's sel f- r eport was f i l led out bef ore t he bir t h of t he chi ld,and the chi ld 's rat ings were f i l led out by their adopt ive parents over 24 months later . This re lat ionship




pg 11

was found at 24 months, but not at 12 months. The inabi l i ty t o d iscover a re lat ionship betw een infantshyness at 12 months and mater nal personal i ty may be due t o behavioral and emoti onal developmentalchanges t hat occur in t he chi ld bet ween t he f i rst and second year of l i fe. This f inding suggest s t hepresence of a genetic com ponent f or shyness in young chi ldren, and i t a lso indicat es t he genet iccomparabi l i t y betw een infant shyness and low sociabi l i t y in t he adul ts ' sel f- r eport .

For bot h adoptive and nonadoptive fam i l ies, parent al rat ings of inf ant shyness were also found to

be relat ed t o mot hers' sel f- r eports of shyness, low sociabi l i t y and int roversion, t hereby suggest ing theinf l uence of shared home environment. In part icular , a Personal Growt h fact or fr om t he FES CohesionScale was found to be rel ated t o infant shyness. Famil i es who score high on th is fact or are act i ve incul t ural events, l ike t o learn new t hings, and are involved in a number of recreat ional and social events.This f indi ng is in agreement wi t h an "exposure t o novel ty" hypot hesis put f orward by Schaffer (1966) andby Kagan, Kearsley, and Zelazo (1977). The "exposure t o novelt y" hypothesis suggest s t hat shy mot hers donot expose themselves or t heir inf ants to novel si tuat ions, t hereby reinf orcing shy t endencies in t hechi ldren. This l ink was found for both adopti ve (shared environment only) and nonadoptive (sharedbiological and environmental f actors) fami l i es, suggest ing that fami ly environment must account for someof t he resemblance bet ween parent and infant shyness.

Jeffrey Gray's Model for Behavioral InhibitionGray's (1971, 1982) bio logical ly based m odel of t emperament , most ly developed f rom r esul t s of

animal research, includes three const ruct s t hat are very re levant t o a discussion of behavioral inhib i t ionand shyness in chi ldhood. Gray has ident i f i ed t wo ort hogonal tem perament al d imensions of behavioralinhib i t ion (anxiety) and behavioral act ivat ion ( impulsivi t y) . Increasing levels of proneness t o anxiety orbehavioral inhib i t ion, identi f ied at the physiological level wi th the act ion of the septal-h ippocampalsyst em, are seen in Gray's theory t o ref lect t he person's sensi t iv i t y t o novel ty, t o signals of non-rewardand punishment , and to innate fear st imul i . Increasing levels of behavioral act i vat ion or impulsivi ty, onthe other hand, identi f ied at the physiological level wi th the medial forebrain bundle, are seen to ref lecthigher proneness t o respond to signals of rew ard or non-punishment . An addi t ional tem perament alvar iable, neurot icism, or pr oneness t o dist ress, i s seen to be a f unction of t he operation of t he arousaldue to bot h act iva t ion and inh ibi t ion .

In situations where a child's responses have resulted solely in reward, individual differences inapproach wi l l depend upon the st rength of t he behavioral act ivat ion syst em (BAS). In si t uations where a

child's responses have resulted solely in punishment, or when there is a new or fear-inducing stimulus,individual d i f f erences wi l l depend upon t he st rength of t he behavioral inhib i t ion syst em (BIS). Insituations where children's approach responses have been alternately rewarded and punished or whereboth aspect s of r eward and punishment are present, as in t he chi ld 's meet ing of a st ranger, whet her anapproach wi l l occur wi l l b e a function of t he operation of bot h the BAS and the BIS. Thus, chi ldr en wit hlow act ivat ing t endencies may be unl ikely t o show rapid approach, even when t hey are not verysuscepti b le to behavioral inhib i t ion. On t he other hand, chi ldren who are high on both act ivat ion andinhibi t ion tendencies would be expected t o show rapid approach under ci rcumst ances of f ami l iar i t y andnon-threat , but mi ght be highly inhib i t ed under condi t ions of punishment , novel ty, or t hreat. Thesechi ldren w ould be expected t o be especial ly var iable in t heir behavior, depending upon condi t ions ofnovel ty- f ami l iar i t y, chal lenge or punishment . Gray's model a l lows for t he import ant possibi l i t y thatchi ldren can have both approach and inhibi t ion t endencies.

Research by Schaff er and his colleagues and in our own l aborat ory also suggest s t hat approach

t endencies are clear ly present by six months of age, but t hat t here wi l l be increasing development of abehavioral inhib i t ion syst em dur ing the l ast hal f of t he f i r st year of l i f e. Thus Schaff er (1974) argues t hatthe important change occurr ing in the th ird quarter of the f i rst year of l i fe is not the onset of avoidanceresponses in young children but rather the onset of inhibition of children's approach responses.

Schaff er and hi s col leagues (Schaff er , Greenwood, & Perry, 1972) conducted a longi tudinal st udyin which 20 chi ldren wer e observed mont hly fr om 6 to 12 mont hs in t heir responses t o unfami l iar st imul i .Even at 6 months, chi ldren showed by their l ooking t imes that t hey could di f fer enti ate bet ween novel andfami l iar object s. However, at 6 mont hs, t he infant s approached unfami l iar object s " impulsively andimm ediately" (Schaffer , 1974, p. 14). At 8 months and beyond, however, lat ency to reach and grasp was




pg 12

clear ly inf l uenced by fami l i ar i t y. Infants now showed hesi t at ions, somet imes but not a lways accompaniedby dist ress and/ or avoidance. When t hese older infants made contact w i t h the object , i t was l ikely t o bedone cautiously.

In a longi tudinal study, we have also f ound increases in infants' latency t o reach and grasp t oyst hat are unfam i l iar and int ense (sound and movement producing) dur ing t he last hal f of t he f i rst year ofl i f e (Rothbart , 1988). We have also found that indivi dual d i f f erences in latency to approach low intensi ty

st imul i are re lat ively st able from 6.5 t o 10 mont hs and beyond t o 13.5 mont hs of age; t hat is, somechi ldren approach object s much more r apidly t han other inf ants, a sign of individual d i f f erences inbehavioral act ivat ion or Gray's BAS. Individual d i f f erences in lat ency to approach high intensi t y st imul i(Gray's BIS) do not show rel at ive st abil i t y across t his age peri od. These find ings are congruent w it h theint erpret at ion t hat behavioral inhib i t ion to int ense and unfami l iar st im ul i is developing across t h is ageperi od. They also suggest t hat indi vidual dif fer ences in approach as assessed under condit ions unlik ely t oel ic i t behavioral inhib i t ion (safe and fami l iar ci rcumstances) can be observed both bef ore and aft er t hedevelopmental onset of behavioral inhib i t ion and that t hey show st abi l i t y from an ear ly age.

Consider ing now t he quest ion of t he developmental st abi l i t y of indivi dual d i f f erences in shynessand behavioral inhib i t ion past 13.5 mont hs, Reznick et a l . ( i n press), using somewhat d i f f erent st imul i andobserving di f f erent inhib i t ory responses, have f ound some stabi l i t y of behavioral inhib i t ion fr om 14mont hs t o later ages. In long-t erm studies of longi tudinal stabi l i t y, var iables closely re lat ed to behavioralinhib i t ion and shyness have also fr equently em erged from t est s for stabi l i t y of m ult ip le personal i t ymeasures. Thus Honzik (1965) has not ed that Fels Longit udinal St udy subj ect s showed stabil i t y from ear lychi ldhood to adul t hood for g ir ls and from middl e chi ldhood to adul t hood for boys on "social inter act ionanxiet y" versus "spont aneit y" (Kagan & Moss, 1962).

In addi t ion, Tuddenham (1959) f ound the greatest longi t udinal st abi l i t y among his personal i tymesures for variables connoting "spontaneity" versus "inhibition" in subjects 14 to 33 years from theOakland Growth Study, Bronson (1972) reported stabil i ty on "introversion" versus "extraversion" and"excessive r eserve" versus "spont aneit y" fr om 21 m ont hs to 18 years, and Schaeff er and Bayley (1963)report ed t heir most stable dimension fr om bir t h to 18 years t o be "act ive, extr averted" versus " inact ive,int rovert ed" behavior. St abi l i t y of i ndividual d i f f erences in shyness has also been report ed in cl in ical j ud gm en t s o f a gr ou p of chi l dren f rom ages 7 t hrou gh 14 (Mac f ar l an e, Al l en , & Honz ik, 1954) , in peerrat i ngs of shyness of chi ldr en betw een the t h ird grade and the f i f t h grade (Coie & Dodge, 1983), and int eachers' rat ings of shyness of chi ldr en bet ween ages 10 and 13 (Backt eman & Magnusson, 1981). Finally,

in a fo l l ow-up study of subj ects from t he Berkeley Guidance St udy (Macfar lane, Al len, & Honzik, 1954)seen 30 years lat er, shy boys in comparison wi t h t hose less shy w ere f ound t o have delayed entr y int omarr iage, parent hood and st able career, and shy gir ls t o have fo l l owed a more t radi t ional female rol e ofrear ing chi ldren and homemaking, wi th ei ther no work history or work terminated at marr iage orchi ldbir t h (Caspi , Elder, & Bem, 1988).

Behavioral Inhibi t ion, Shyness, and Psychopathology in Chil drenThe DSM-IIIR (APA, 1987) includ es disorder s in whic h anxiet y plays a prom inent role as f al l i ng

wit h in t he classi f icat ion of anxiety disorders. For chi ldren, t hese disorders pr im ar i ly consist of separati onanxiety, avoidant d isorder, overanxious disorder, phobic disorder, panic disorder, and obsessive-compul sive disorder. Each of th ese disorder s has it s own uniq ue set of specif ic symp t oms and level ofimpairm ent. However, t hey share the character ist ic of an abnormal ly h igh level of anxiety.Unfort unately, vi r t ual ly no st udies have invest igat ed t he prevalence of t hese disorders in the general

populat ion. Inst ead, researchers have chosen to concentrat e their ef for t s on fears commonly f ound inchi ldhood at nonpathological levels (e.g., Lapouse & Monk, 1958).

One group of chi l dren w ho may have a connection t o behavioral inhib i t ion is a group labeled asbeing social ly wi t hdrawn. These chi ldren are typical ly identi f ied by t heir low rates of inter act ions wit hpeers. Ear ly st udies seemed t o suggest t hat t hese chi ldren w ere at no r isk f or developing any behaviorproblems or peer re j ect i on. However, recent st udies have indicated otherw ise. Rubin (1985)demonst rated t hat social ly isolated chi ldren w ere less dominant i n their peer int eract ions and reportednegative sel f-percept ions of t heir social , cogni t ive, physical and general att r ibut es. Poor academicachievement has also been shown t o be related t o extr eme wi t hdrawal according t o teacher report




pg 13

(Green, Forehand, Beck, & Vosk, 1980). Numerous fact or-analyt ic studies using parent and t eacherreport have indicated t hat t here is an anxious-wit hdrawn dim ension of chi ld behavior, suggest ing thatsocial wi t hdrawal m ay be related t o other d i mensions such as depression and anxiety (Rubin, 1985). Thispossibi l i t y is fur t her re inf orced by t he longi tudinal studies of behavioral inhib i t ion, separati on dist ress,depression and anx iet y in rhesus monkeys by Suomi and his coll eagues, discussed above(Higley & Suomi ,in press). The pr imat e research suggest s t hat research relat ing behavioral inhib i t ion to probl ems relat ingt o separation and depression would be of great int erest .

The relat i onship bet ween social wi t hdrawal and behavioral problems was recentl y invest igat ed bySt rauss, Forehand, Smit h, & Frame (1986). A sample of social ly w i t hdrawn and social ly out going 2nd-5t hgraders were selected on t he basis of t eacher and peer report . The chi ldren were given a number of sel f-report measures, i ncluding sel f-concept , depr ession and anxiety scales. The teachers f i l led out abehavior checkl ist on each chi ld and peers submit t ed sociomet r ic rat ings. When compared t o social lyoutgoing peers, social ly w i t hdrawn chi ldren w ere found t o have more int ernal iz ing problems and moredisrupt ed relat ionships wit h peers. Speci f ical l y, w i t hdrawn chi ldren w ere descr ibed as being less wel l -l iked, m ore disl iked, and less enjoyable as playmat es by their p eers. Furt hermore, t hese chi ldrenreport ed more depressive sympt oms and higher rates of anxiety. Taken together, t hese f indings suggestt hat social ly w i t hdrawn chi ldren m ay be at r isk for developing aff ect i ve or anxiety disorders and at r isk ofbeing reject ed by peers.

In re lat ing later anxiety re lated behavior problems to ear ly temperamental character ist ics, Batesand his col leagues have att empt ed to predict t he later development of behavior problems fr om ear lynegative emot ional i t y in infancy. In t h is work, r eviewed by Bates (1987), a di f f icul t t emperament i ninfancy (defined as frequent and intense expressions of negative aff ect) predict ed both int ernal iz ing andexter nal iz ing problems when the subject s were l ater assessed at 3-6 years. Addi t ional ly, ear lyunadapt abi l i t y t o novel persons and si t uations as assessed by parent -report in t he Infant Character ist icsQuestionnaire at age 6 months predicted later anxiety problems, but not act ing-out problems ( the latterwere relat ed to ear ly act ivi t y management problems), as seen by the mot her. These resul t s suggest t hatear ly temperamental predisposi t ions to fearfu lness may contr ibute to later problems, but moreobservational research wi l l be needed in th is area. The topic of t emperament and behavior problems isan import ant one, and addi t ional longi tudinal research in t h is area is much needed.

Summary

In th is paper we have suggest ed t hat some of t he components of t he const el lat ion of behaviorald imensions, including behavioral i nhib i t ion, shyness, and social anxiety, have their roots int emperament al d isposi t ions. These disposi t ions are seen to be especial ly re lat ed to inhibi t ed orwit hdrawing behavior and autonomi c reactivi t y to novel t y and chal lenge. We have also suggest ed that , asevidenced in si t uations where bot h rewarding and novel or chal lenging st i mul i are pr esent, latency t oapproach the st imulus wi l l be a function of two temperamental d imensions, behavioral act ivat ion andinhibi t ion, rat her t han only one, behavioral inhib i t ion. More cogni t ive aspects of social anxiety are seent o extend beyond the domain of t emperament t o include cogni t ive representat ions of sel f and ot hers.Thus an individual not predisposed t o social fear m ay come t o exper ience social anxiety due t o t heexper ience of extensive cr i t ic ism f rom ot hers. There is current ly some evidence to suggest t hat ear lyfearf u lness wi l l be predict ive of l ater social anxiety (and possibly suscepti b i l i t y t o depression), but muchmore l ongi t udinal research is needed in t h is area.




pg 14

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1990 Temperament Behav Inhib Shyness Rothbart-Mauro