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Journal oi Personality and Social Psychology1965, Vol. 1, No. 6, 589-595

INFLUENCE O F M ODE L S ' R E IN FOR C E M E N T C ON T IN GE N C IE SON THE ACQUISITIONOF IM IT AT IVE RESPONSES'A L B K R T B A N D U R A2

Stanford UniversityIn order to test th e hypothesis that reinforcements administered to a modelinfluence th e per formance but not the acquisition of matching responses,groupsof children observed an aggressive film-mediated model either rewarded,punished, or left without consequences. A postexposure test revealed thatresponse consequences to the model had produced differential a m o u n t s ofimitative behavior . Children in the model-punished condit ion perform ed sig-nificantly fewer matching responses than children in both th em odel-rewardedand the no-consequences groups. Children in all 3 treatment conditions werethen offered attractive reinforcers contingent on their reproduc ing th e model'saggressive responses.T he introduct ion of positive incentives completely wipedout the previously observed per formance differences, revealing an equivalenta mo u n t of learning among children in the model-rewarded, model-punished,and the no-consequences conditions.

It is widely assumed that the occurrenceofimi tat ive or observational learning is con-t ingent on the administrat ion of reinforc ingstimuli either to the model or to the observer.According to the theorypropoundedby Millerand Bollard (1941) , for example, th e neces-sary conditions for learning through imitationincludea motivatedsubject who is positivelyreinforced f or m atching the rewarded behaviorof a model during a series of init ially random,trial-and-error responses. Since this concep-tualization of observational learning requiresthe subject to per form the imitative responsebefore he can learn it , this theory evidentlyaccounts more adequately for the emission ofpreviously learned matching responses, thanfo r their acquisit ion.Mowrer's (1960) proprioceptive feedbacktheory similarly highlights the role of rein-forcement but , unl ike Mil ler and Dollard w horeduce imitation to a special case of instru-mental learning, Mowrer focuses on the clas-sical condit ioning of positive and negat iveemotions to m atching response-correlatedstimuli . Mowrer dist inguishes tw o forms ofimi tat ive learning in t e rms of whether the ob-server is reinforced directly or vicariously. Inthe former case, the model performs a re-

1This investigation was supported by ResearchGrant M-5162 from the National Instituteso fH eal th,United States Public Health Service.2T he a u t ho r is indebted to Carole Revellc whoassisted in collecting th e data.

sponse and simultaneously rewards the ob-server. If the modeled responses are thuspaired repeatedly w ith positive reinf orce m entthey gradually acquire secondary rewardvalue.The observercan then administer posi-t ively condit ioned reinforcers to himself sim-ply by reproducing as closely as possible themodel's positively valenced behavior. In thesecond, or empathet ic form of imitat ive learn-ing, th e model not only exhibits th e responsesbut also experiences the re inforcing conse-quences . It is assumed that th e observer , int u r n , experiences empathetically both the re-sponse-correlated st imuli and the responseconsequencesof the model'sbehavior. As a re-sult of this higher-order vicarious condit ion-ing, the observer will be inclined to reproducethe matching responses.

There is some recent evidence that imita-t ive behavior can be enhanced by noncont in-gent soc ial reinforcementfrom a model (Ban-du ra & Hu ston, 1961), by response-cont ingentreinforcers adminis tered to the model (Ban-du ra, Ross, & Ross, 196 3b; W alters, Leat,&Mezei, 1963),and by increasing the reinforc-in g value of matching responses per se throughdirect reinforcem ent of the part icipant ob-server (Baer&Sherman, 1964).Nevertheless,re inforcement theories of imitation fail to ex-plain the learning of matching responses whenthe observer does not per form the model 's re-sponses during the process of acquisit ion, andfo r which reinforcersare not delivered either

589

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590 ALBERT B A N D U R Ato (h e model or to the observers (Bandura e tal., .1961, 1%3a).The acquis i t ionofim i ta t ive responses u n d e rthe lat ter condi t ions appears to be a c co u n t e dfo r m or e adequately b y a con t igu i ty theoryof observat ional learning. According to thela t ter conceptual iza t ion (B and u ra , in press;Sheffield, 1961) , when an observer wit-nesses amodelexhibit asequenceof responsesthe observer acqui res , through cont iguous as-sociation of sensory events , perceptual andsymbolic responses possessing cu e propert iesthat are capable of eliciting, at some timeaf ter a demonstrat ion, overt responses corre-sponding to those that had been modeled.Some suggestive evidence that th e acquisi-tion of matching responses may take placethrough cont igui ty , whereas re inforcementsadministered to a model exert their major in -fluence on th e performance of imitativelylearned responses, is provided in a study inwhich models were rewarded or pun i shed forexhibit ing aggress ive behavior (Bandura etal., 1 9 6 3 b ) . A l t h oug h children who had ob-served aggressive responses rewarded subse-qu ent ly reproduced the m odel' s behavior whi lechildren in the model-punished condit ionfailed to do so, a number of the subjects inthelatter group described in postexperimentalin terv iews th e model 's repertoire of aggressiveresponses wi th cons iderab le accu racy. Evi -den t ly , ihey had learned the cognit ive equiva-lents of the model's responses bu t they werenot translated into their motoric forms. Thesef indings highl ighted both the impor t ance ofdis t inguishing between learning and perform-ance and the need for a systematic s tudy ofwhether r e in for cemen t is pr im ari ly a learn ing-related or a per formance-related variable.1n the present experiment children observeda f i lm-media ted model who exhibi ted novelphysical and verbal aggressive responses. Inone treatment condit ion th e mode l was se-verely punished; in a second, th e model w asgenerously rewarded; while the third condi-tionpresented no response consequences to themodel . Following a postexposure test of imi-tat ive behavior, children in al l three groupswere offered at t ract ive incentives con t ingenton their reproducing the models ' responses soas to provide a more accura te index of learn-ing. It was predicted that re inforcing conse-

quences to the mode l would resul t in signifi-can t differences in the per formance of i m i t a -t ive behavior with th e m ode l - r e w a r de dg r o u pdisplaying the h i g h e s t n um b e r of di f ferentclasses of ma t ch ing responses, followed byth e no-consequences and th e model -punishedgrou ps, respect ively. I n accordance with previ-ou s findings ( B a n d u r a et al., 1961, 1963a) itwas also expected that boys would pe r formsignif icantly more imitat ive aggression thangirls. It was predicted, however, that the in-t roduc t ion of posit ive incentives would wipeout both reinforcement-produced and sex-l inked pe r formance differences, revealing anequ iva len t amoun t of learning am ong ch i ldrenin the three t rea tment condi t ions .

METHODSubjects

The sub jec ts were 33 boys and 33 girls enrolled inthe S t an fo r d Universi ty Nu rsery School.They rangedin age f rom 42 to 71 months , w i th a m e a n age ofSI m o n t h s . The children were assigned randomly toone of three t rea tment condi t ions of 11 b o y s an d 11girls each.Tw o adult malesserved in the role of models, andone female exper imenter conduc ted the s tudy for all66 chi ldren.Exposure Procedure,

The chi ldren were br ou gh t ind iv idual ly to a sem i-darkened r o o m . The exper imenter i n f o r me d th e childt h a t she had some bus iness lo a t tend to before theyco u ld proceed to the surpri se p layroom, bu t tha tdu r in g the waiting period the child might w a l c h atelevised p r o g r a m . Af t e r the child was sca led , th eexper imenter walked over lo th e television console,ostensibly tuned in a program and then departed . Afilm of approximate ly S minutes dura t ion depic t ingthe modeled responses was shown on aglasslenscrcenin th e television console b y m e a n s of a rear p ro j ec -t ion arrang em ent , sc reened f rom the child's view b ylarge panels. The televised f o r m of presentation wasutil ized p r imar i l y because at tending responses totelevised stimuli arc strongly conditioned in childrenand this procedu re wou ld there fore serve to enhanceobservat ion which is a necessary condition for theoccu r rence o f imi ta t ive learn ing.The f i lm began with a scene in which the modelwalked up to an adult-size plastic Bobo doll andordered him to clear th e way. After glaring for am o m e n t a t t h e n on compl ian t antagonis t th e mode lexhibited f o u r novel aggressive responses each ac-compan ied by a distinctive verb alization.

First, th e model laid th e Bobo dol l on its side, saton i t , and punched i t in the nose whi le remarking , Pow, right in the nose , boom , boom. The m odelthen raised the doll and pommeled it on th e headwith a mal le t . Each response w as accompanied b y

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A C Q U I S I T I O N O F I M I T A T I V E R E S P O N S E S 591the verbalization, Sockeroo . . . stay down. Fol-lowing th e mallet aggression, th e model kicked th edoll about th e r o o m , and these responses were inter-spersed with th e com m en t , F ly away. Finally, th emodel th rew rubber bal ls at the Bobo doll, eachs t r ike punctuated with Bang. This sequence ofphysically and verbally aggressive behavior was re-peated twice.The component responses that enter into the de-v e lopmen t o f mo r e complex novel pat terns of be-havior are usual ly presen t in children's behavioralrepertoires as products e i ther of m a t u r a t i o n or ofprior social learning. Thus, while most of the ele-men t s in the modeled acts had undoubtedly beenpreviously learned, th e par t icu lar pat tern of com-ponents in each response, an d their evocation by spe-cific s t imulus objects, were relatively un ique. Forexample, children can manipulate objects , sit ont h em , pun ch th em , and they can make voca l re-sponses, but the likelihood that a given child wouldspontaneous ly place a Bobo doll on its side, sit on it,p u n c h it in the nose and remark , Pow . . . b o o m ,boom, is exceedingly remote. Indeed, a previousstudy utilizing th e same s t imu l us objects has shownthat th e imitative responses selected for th e presentexperiment have virtually a zero probability of oc-curr ing spontaneous ly among preschool ch i ldren(Bandura c t al., 1961) and, therefore, m e e t th e cri-terion of novel responses.The rewarding an d punishing contingencies associ-ated with th e model's aggressive responses were in -troduced in the closing scene of the f i lm.

For children in the model- rewarded condi t ion , asecond adult appeared with an abundant supply ofcandies and sof t drinks. H e in fo r med th e m o d e l thathe was a s t rong cham pion and that h is superb ag -gressive perf orm anc e clearly deserved a generoustreat. H e then poured him a large glass of 7-Up, an dreadily supplied additional energy-bu i lding n ou r i sh -ment including chocolate bars , Cracker Jack pop-corn , and an assortment of candies. While the modelwas rapidly c o n s u m i n g th e delectable treats, his ad-mir e r symbolically reinstated th e modeled aggressiveresponses an d engaged in considerable positive socialrein forcement .

For children in the model-punished condi t ion , th ereinforcing agent appeared on the scene shaking hisfingerm enacingly and commentingreprovingly, Heythere, you b igbully. You quit picking on that clown.I won't tolerate it. As the model drew back hetripped and fell, the other adult sat on the modeland spanked h im with a rolled-up magazine whiler emind ing him of his aggressive behavior. As themodel ran off cowering, the agent forewarned him, If I catch you doing that again, you big bu lly, I'llg ive you ahard spanking. You quit acting that way.

Children in the no-consequences condition viewedthe same f i lm as shown to the other tw o g roupsexcept that no re inforcement ending w as included.Performance Measure

Immediately following th e exposure session th echildren were escorted to anexperimental room that

contained a Bobo doll, three balls , a mallet and peg-board, dar t guns , cars , plastic farm animals, and adoll house equipped with f u r n i t u r e and a doll family .By providing a variety of stimulus objects the chil-dren were at l iber ty to exhibit imitative responses orto engage in nonimitat ive fo r ms of behavior .After the experimenter instructed the child that hew as free to play with th e toys in the r o o m , sheexcused herself supposedly to fetch additional playmaterials . Since many preschool children are reluc-tant to remain alone and tend to leave after a shor tperiod of t ime , the exper imenter reen tered the roommidway th rough th e session and reassured th e childthat shewould return shortly with the goods.Each child spent 10 min u tes in the test roomdur ing which t ime his behavior was recorded every5 seconds in terms of predetermined imitative re -sponse categories by j u d g e s who observed th e sessiont h r o u g h a on e- way m i r ro r in an adjoin ing observa-

tion room.Two observers shared th e task of recording th eoccur rence o f matching responses for all 66 children.Neither of the raters had knowledge of the treat-ment condi t ions to which th e children were as-signed. In order to provide an estimate of interscorcrreliability, the responses of 10 children were scoredindependent ly by both observers. Since the imitativeresponses were highly distinctive and requ i r ed nosubject ive in terpretat ion , the raters were v ir tual ly inperfect agreemen t (99%) i n scoring th e match in gresponses.T h e n umber o f different physical and verbal imi-(ative responses emitted spontaneously by the chil-dren cons t i tu ted th e pe r f o r ma n ce measu re .Acquisition Index

At the end of the p e r fo r mance session the experi-menter entered th e room with an assortment of fru i tj u i ces in a co lor fu l juice-dispensing fo u n t a in , andbooklets of s t icker-pic tures that were employed asthe positive incentives to activate into performancew h a t th e children had learned through observat ion .After a brief ju ice treat the children were in fo r med ,that for each physical or verbal imitative responsethat th ey r ep roduced , they wou ld receive a prettyst icker-picture an d additional juicetreats. A n achieve-ment incen t ive w as also in t roduced in order to pro-duce f u r t he r disinhibition and to increase th e chil-dren's motivation to exhibit matching responses. Theexper imenter attached a pastoral scene to the walland expressed an interest in seeing how m a n y sticker-pictures th e child would be able to obtain to adornhis pic ture .The experimenter then asked th e child, Show m ewhat Rocky did in the TV program, Tell m e w h a the said, and rewarded him immedia te ly followingeach matching response. If a child simply describedan imitative response he was asked to give a per-fo r mance demon s t ra t ion .Although learning must be inferred f rom p e r f o r m -ance, it was assumed that th e n u m b e r of dif ferentphysical and verbal imitat ive responses reproducedby the children un der the positive-incentive condi-

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592 A L B E R T B A N D U R APOSIT IVE INCENTIVENO IN ENTIVE

13

oy s GirlsMODEL REWORDED

oy s GirlsMODEL PUNISHED

oys GirlsNO ONSEQUEN ES

FIG. 1. Mean number of different matching re -sponses reproduced by chi ldren as a func t ion o f posi-t ive incentives an d the model' s re info rcem ent con-t ingencies .t ions wou ld serve as a re la t ive ly accu ra te index o fl e a rn i ng .

R E S U L T SFigu re 1 shows th e m e a n n u m b e r of di f -feren t matching responses reproduced by chil-

dren in each of the three t reatment condi t ionsd u r i n g the no- inc ent ive and the posi t ive- in-centive phases of the experiment. A square-roo t t rans fo rmat ion y=V/ + f) was ap-plied to these data to make them amenab leto paramet r i c statistical analyses.Performance Differences

A s u m m a ry of the analysis of variance basedon the perf orm anc e scores is presented in Ta-ble 1. The f indings reveal that re inforcing con-sequences to the model had a signif icant effecton th e n u m b e r of matching responses that th echildren spontaneously reproduced. The main

T A B L I C lA N A L Y S I S or V A R I A N C E OF I M I T A T I V EP E R F O R M A N C E S C O R E S

SourceTreatments (T)Sex (S)T X SWithin groups

*p

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ACQUISITION OF IMITATIVE RESPONSES 593Acquisition-Perform ance Differences

In order toelucidate fur ther th e influenceofdirect and vicariously experienced reinforc e-ment on imi tat ion, the differences in match-in g responses displayed under nonreward andposi tive-incentive conditions for each of thethree exper imental t reatments were evaluatedby the f-test procedure for correlated means.Table 4 shows that boys w ho witnessed th emode l ei ther rewarded or lef t without conse-quences performed al l of the imitative re-sponses that they had learned through obser-vation and no new matching responsesemerged when posi tive re in forcers were madeavailable. On the other hand, boys who hadobserved the model punished and girls in allthree t reatm ent condi t ions showed significantincrements in imitative behavior when re -sponse-contingent reinf orc em ent was later in-t roduced .

DISCUSSIONThe resu l ts of the present expe rim ent lendsuppor t to a con t igu i ty theory of im i tat ive

learning; reinforcements administered to themodel influenced th e observers ' p e r f o r m an c ebu t not the acquisi t ion of ma tch ing responses.It is evident from the findings, however ,

that mere exposure to model ing s t imul idoesnot provide th e suffic ient condi t ions for imi -tative or observational learning. The fac t thatmost of the children in the experiment failedto reproduce the entire repertoire of behavio rexhibi ted by the model , even under posi tive-incentiveconditions designed todisinhibitandto elicit matching responses, indicates thatfactors other than m ere con tigu i ty of sensorystimulation undoubtedly inf luence imi tat iveresponseacquisition.Exposing aperson to a complex sequenceo fs t imulat ion is nogu aran tee thathe willattend

TABLE 3ANALYSIS01?VARIANCE 01? IMITATIVE LEARNING SCORES

TABLE 4SIGNIFICANCE OP TH E ACQUISITION-PERFORMANCEDIFFERENCES IN IMITATIVE RESPONSES

SourceTreatments (T)Sex (S)TX SWithin groups

21260

MS0.020.560.020.09

Group

Total s a m p l eBoysGirls

Tr ea tmen tcondi t ions

Reward12.38*0.743.33**

Pun i s h m e n t5.00***2.26*5.65***

Noconscqucnt2 .67**1.542.18*

6.22*

< O S

P

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594 ALBERT BANDURAtained in the observer 's repertoire. A personwho possesses a very narrow repertoire of be-havior, for example, will, in all probability,display only fragmentary imitation of a mod-el's behavior; on the other hand, apersonw hohas acquired most of the relevant componentsis likely to perform precisely matching re-sponses following several demonstrat ions. Inth e case of young preschool children theirmotor reper toi res are more highly developedthan their repertoires of verbal responses. Itis , perhaps, for this reason that even in theposi tive-incentive condi t ion , ch i ldren repro-duced a substantially higher percentage(67 f c of imitat ive motor responses thanm atching v erbal iza t ions ( 2 0 % ) . Asimilar pat-tern of differential imitat ion was obtained ina previous experiment ( B a n d u r a & Hus ton ,1961) in which preschool children served assubjects .It is apparent from the foregoing discussiont h a t considerably more research is needed iniden t i fying variables that combine wi th con-t iguousstimulationingoverningtheprocessofim itative response ac qu isition.It is possible, of course , to in terpre t th epresent acquisition data as reflect ing the op-erat ion of generalizat ion from a prior historyof reinforcement ofimitative behavior. Withinany social group, models typically exhibit th eaccumulated cultural repertoires that haveproved most successful for given st imulus si t -ua t ions ; consequent ly, matching the behaviorof other persons, particularly th e superiors inan age-grade or prestige hierarchy, will maxi-mize pos i t ive re inforcement and minimizethe frequency of aversive response conse-quences. Since both th e occurrence and theposit ive reinforcement of matching responses,whether by accident or by in tent , are inevita-ble during the course of social development ,no definitive resolution of the reinforcementissue is possible,except, throu gh an experimentut i l iz ing organisms that have experiencedcomplete social isolation from birth. It is evi-dent, however, that contemporaneous rein-forcements areunnecessaryfor theacquisitionof new matching responses.The f inding that boys perform more im i t a -tive aggression than girls as a resul t of ex-posure to an aggressive male model, is in ac-cord with results from related experiments

( B a n d u r aetal., 1961, 1963a) .The additionalfinding,however,that the introduct ion of posi-tive incentives practically wiped out the priorperformance disparity strongly suggests thatthe frequently observed sex differences inaggression (G ooden ou gh, 1931; Johnson,1951; Sears, 1951) m ay reflect primari ly di f -ferences in willingness to exhibit aggressiveresponses, rather than deficits in learning or masculine-role identificat ion.The subgroups of children who displayedsignif icant increments in imi ta t ive behavioras a f u nc t i on of pos i t ive re inforc em ent wereboys who had observed the aggressive modelpunished, and girls for whom physically ag -gressive behavior is typically labeled sex inap-propriate and nonrewarded or even negativelyreinforced. The inhibitory effects of differingreinforcement histories for aggression weredearly reflected in the observat ion that boysweremore easily disinhibited than girls in thereward phase of the experiment . This factormay account for the small sex difference thatwas obtained even in the positive-incentivecondit ion.The present s tudy provides fu r t he r evidencethat response inhibition and response disinhi-bit ion can be vicar ious ly t ransmit ted throughobservation of reinforcing consequences to amodel 's behavior. It is interest ing to note ,however, that th e per formance by a mode lo fsocially disapproved or prohibited responses( for example, kicking, s t r iking wi th objects )wi thou t the occur rence of any aversive conse-quences m ay p r oduce dis inhib i tory effectsanalogous to a pos i t ive re inforcement opera-l ion.Thesefindings arc similar to results froms tudies of direct reinforcement (Crandal l ,Good, &Crandall , 196 4) in which nonrewardfunct ioned as a posit ive reinforcer to increaseth e probab i l i t y of the occurrence of former lypunished responses.Punishment adminis tered to the model ap-parent ly fu r t he r reinf orc ed the girls ' existinginhibit ions over aggression and produced re-markably l i t t le imitat ive behavior; th e boysdisplayed a similar, though not significant,decrease in imi ta t ion . This difference may bepartly a funct ion of the relat ive dominanceofaggressive responses in the repertoires of boysand girls. It is also possible that vicar ious re-in forcement forboys,deriving from the mod-

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ACQUISITION OF IMITATIVE RESPONSES 595el's successful execut ionofag gressive behav ior( tha t is , overpoweringthe noncom pliant ad-ve rsa ry) , m ay have reduced th e effects ofexternally administered te rmina l pun ishmen t .These factors, as well as the model 's self-re-warding and self-pu nishing reactions follow-ing the display of aggression,will be investi-gated in a subsequen texperim ent.

R E F E R E N C E SB A S E , D. M., & S H E R M A N , J. A. Re i n f o r ce me n t con-trol of generalized i m i t a t i o n in y o u n g children.Journal of Experimental Child Psychology, 1964,

1, 37-49.B A N D U R A , A. Soc ia l learning through imi ta t ion. In M.R. Jones (Ed . ) , Nebraska symposium on motiva-tion: 1962. Lincoln: Univer . Nebraska Press, 1962.P p. 211 -269 .B A N D U R A , A. Vicarious processes: A case of no- tr ia llearning . In L. Berkowi tz (Ed.), Advances inexperimental social psychology. Vol. 2. New Y o r k :Academic Press, 1965, in press.

B A N D U R A , A., HUSTON, A L E T H A C. Ident i f icat ion asa process of inc identa l learning .Journal of Abnor-mal and Social Psychology, 1961, 63 , 311-318.B A N D U R A , A., Ross, D O R O T H E A , & Ross, S H E I L A A.Transmission of aggression through imi tat ion ofaggressive models . Journal of Abnormal an d SocialPsychology, 1961, 63 , 575 -582 .B A N D U R A , A., Ross, D O R O T H E A , & Ross, SHEILA A.

Imitation of film-mediated aggressive models.Journal of Abnormal an d Social Psychology, 1963,66, 3-11. (a)B A N D U R A , A., Ross, D O R O T H E A , & Ross, S H E I L A A.Vicarious re inforcement and imi ta t ive learning .Journal of Abnormal an d Social Psychology, 1963,67 , 601-607. (b )B A N D U R A , A., & W A L T E R S , R. H. Social learning an dpersonality development. New York : Holt, Rine-hart, &Winston, 1963.C R A N D A L L , V I R G I N I A C. , G O O D , S U Z A N N E , C R A N D A L L ,V. J. The re in fo rcemen t effects of adult reactions

and non-reactions on children's achievement ex-pectations: A replication study. Child D evelop-ment, 1964,35, 385-397.G O O D E N O U G I I , F L O R E N C E L. Anger in young children.Min neapolis: U niver. Minn esota Press, 1931.J O H N S O N , E L IZ A B E T H Z . Att i tudes of children toward

au tho r i ty aspro jec ted in their dollplay at two agelevels. Unpubl i shed doc tora l d isser ta t ion, HarvardUniversi ty, 1951.McGuiRE , W. J. Interpolated mo t i v a t i ona l state-m ents wi thin a program m ed series o f ins tru c t ionsas a distribution of practice factor. In A. A. L u m s -da in e (E d . ) , Student response in programmed in -struction: A symposium. Washington, D . C .: Na-t i ona l Academy of Sc iences , National ResearchCouncil, 1961. Pp. 411-415.

MILLER, N. E., & D O L L A R D , J. Social learning an dimitation. New Haven: Yale Univer. Press, 1941.M O W R E R , O. H. Learning theory and the symbolic

processes. N ew York: Wiley, 1960.S E A R S , P A U L I N E S. Doll play aggression in no rma ly o u n g chi ldren: Inf luence of sex, age, siblingstatus, father's absence. Psychological Mo nographs,1951, 65(6 , Whole No. 3 2 3 ) .SHEFFIELD, F. D. Theoretical considerations in thelearning of complex sequential tasks f rom demon-stration and practice. In A. A. Lumsda ine (Ed.),Student response in programmed instructions: Asymposium. Washington, D . C.: National Acad-emy of Sciences, Nat ional R esearch Cou ncil, 1961.Pp. 13-32.

SHEFFIELD, F. D., & M A C C O B Y , N. S u m m a r y and in-terpretation on research on organizational princi-ples in cons t ruc t i ng f i lmed demonstra t ions . In A.A. Lum sda ine (E d . ) , Student response in pro-grammed instruction: A symposium. Washington,D . C.: Na t iona l Academy of Sciences, NationalResearch Cou nc i l , 1961. Pp. 117-131.W A L T E R S , R. H., L E A T , M A R I O N , & MEZEI, L. Inhi-bition and disinhibi tion of responses through em-pathetic learning. Canadian Journal of Psychology,

1 9 6 3 , 17 , 235-243.(Received October 21, 1963)