Psychological Review1567, Vol. 74, No. 1, 29-39

MOTIVATIONAL AND EMOTIONAL CONTROLSOF COGNITION 1

HERBERT A. SIMONCarnegie Institute of Technology

The central nervous system is a serial information processor that mustserve an organism endowed with multiple needs, and living in an en-vironment that presents unpredictable threats and opportunities. Theserequirements are met by 2 mechanisms: (a) goal-terminating mecha-nisms, permitting goals to be processed serially without any 1 monopo-lizing the processor, (b) interruption mechanism, having the propertiesusually ascribed to emotion, allowing the processor to respond tourgent needs in real time. Mechanisms of these kinds, to control thedirection of attention and activity, have been incorporated in some in-formation-processing theories of human cognition, and their furtherelaboration will permit these theories to explain wider ranges ofbehavior.

Considerable progress has been madein the last decade in accounting for hu-man cognitive performances in termsof organizations of simple informationprocesses (Reitman, 1965; Simon &Newell, 1964). Information-process-ing theories, however, have generallybeen silent on the interaction of cogni-tion with affect. Since in actual humanbehavior motive and emotion are majorinfluences on the course of cognitivebehavior, a general theory of thinkingand problem solving must incorporatesuch influences.

Critics of information-processing the-ories and of computer simulation ofhuman thinking point, quite correctly,to this lacuna as a major deficiency ofthe theories. Neisser (1963), whose

1 Discussions with my colleague, WalterR. Reitman, about the relations of serialand parallel processing provided much of themotivation for the approach of this paper.I alone accept responsibility for the particu-lar form of the theory of emotional behaviorproposed here. Reitman (1963) has de-scribed part of his own theory. An earlierversion of this paper provided the basis forone of my William James Lectures at Har-vard University, March 1963. Its comple-tion has been aided by research grants fromthe Carnegie Corporation and the NationalInstitutes of Health (MH-07722).

views on simulation are perceptive andinformed, argues that "the view thatmachines will think as man does re-veals misunderstanding of humanthought." He observes that:Three fundamental and interrelated charac-teristics of human thought . . . are con-spicuously absent from existing or con-templated computer programs:

1) human thinking always takes place in,and contributes to, a cumulative process ofgrowth and development;

2) human thinking begins in an intimateassociation with emotions and feelings whichis never entirely lost;

3) almost all human activity, includingthinking, serves not one but a multiplicity ofmotives at the same time [p. 195].

Our purpose here is to discuss thebehavior of humans, not the capabilitiesof computers. Nonetheless, Neisserhas characterized correctly some of thevisibly gross differences between hu-man behavior and the behavior of ex-isting simulation programs. Even ifit were to be argued that the differencesare quantitative rather than qualitative,they would prove conspicuous nonethe-less. Developmental processes play asmall role in existing simulation pro-grams, emotions play almost no role,and most such programs appear to be

29

30 HERBERT A. SIMON

driven by a single top-level goal, ormotive. Progress in theory construc-tion will require us to remove thesedifferences.

This paper will attempt to show howmotivational and emotional controlsover cognition can be incorporated intoan information-processing system, sothat thinking will take place in "inti-mate association with emotions andfeelings," and will serve a "multiplicityof motives at the same time." The ex-panded system will therefore meetNeisser's second and third objections.(Growth and development will be leftto another paper.)

In its assumptions about the mecha-nisms of motivation and emotion, thetheory will follow lines already laiddown by Hebb, Lindsley, and others,for which there is considerable empiri-cal support. The proposed theory con-tains elements of novelty mainly byshowing how relatively familiar mecha-nisms of motivation and emotion canbe integrated in a simple and naturalway with the mechanisms that havebeen postulated in information-process-ing theories of cognition.

"MOTIVATION" OF BEHAVIOR IN ASERIAL PROCESSOR

Two assumptions are central to mostof the existing information-processingtheories of thinking:2 (a) The centralnervous system (CNS) is basically or-ganized to operate in serial fashion; and(&) the course of behavior is regulated,or motivated, by a tightly organizedhierarchy of goals.

Serial OrganisationIt is not easy to state rigorously what

is meant by a "serial" as contrasted2Reitman (1965, Ch. 8) outlines a model,

ARGUS, that is highly parallel in operation.Development of this model has not yetreached a point where its adequacy to simu-late cognitive behavior can be evaluated.

with a "parallel" processor. A serialprocessor, of course, is one in whichonly a few things go on at a time,while a parallel processor is one inwhich many things go on at a time.This distinction is meaningless, how-ever, until we specify how to count"things"—how to recognize a unitaryprocess or object.

The ambiguity extends not only todefining the symbolic units, but to de-fining the time units as well. Anyserial system, given enough time, cando many things. If we only look at itsbehavior periodically, we cannot tellwhether the processes have been carriedout in serial or parallel fashion.

When we say that the human CNSis organized as a serial processor, wemust have in mind, therefore, some no-tion of an "elementary" symbol and an"indivisible" time unit. Since thesimplest reflex actions require about100 milliseconds, we may take this asthe approximate relevant time interval.Since in some memory experiments,the "chunk" (i.e., a single familiarsymbol, like a familiar nonsense sylla-ble, a digit, or a familiar short word)appears to be the significant processingunit, we may consider it the elementarysymbol.

Then the postulate that the humanCNS is serial can be rendered roughlyas follows: The processes that operateduring %o second affect only a fewchunks (about seven, according toMiller, 1956) among all those in short-and long-term memory. More macro-scopic processes are synthesized fromsequences of elementary processes, or-ganized to operate over longer timeintervals. For anything "interesting"to happen in the CNS may requirequite long times—for example, about30 seconds to memorize a nonsense-syllable pair of low association value.During a relatively short interval oftime during which one such process

MOTIVATIONAL AND EMOTIONAL CONTROLS 31

is going on, not much else can or doeshappen.

The plausibility of this postulate restson several kinds of evidence. First,there is a large mass of behavioral evi-dence, both from everyday observationand from laboratory experiments, fora phenomenon called "attention"; andthere is evidence that the span of at-tention—the number of things that canbe attended to simultaneously—is onlya few chunks. To be sure, not every-thing that happens in the CNS goes onat the level of consciousness. Never-theless, certain cognitive processes, atleast, require attention; the numberthat can be within the scope of attentionat one time is very limited.

A second kind of argument for serialprocessing is of a more a priori char-acter: It is difficult to specify how toorganize a highly parallel information-processing system that would behavecoherently. The basic problem is this.Suppose a system, C, has two com-ponents, Cj and C2, operating in par-allel, which interact. From time totime the behavior of Q depends on thecurrent state of C2, and vice versa. Ina simple case, we might have twomemories, Mx and M2, for communica-tion between the two components. Atcertain times, Ct would store informa-tion in Mj, and C2 in M2; likewise,from time to time, Q would take infor-mation from M2, and C2 from Mt.

To obtain coherent behavior fromsuch a system, there would have to bea certain measure of temporal coordi-nation between its components. If Qtakes inputs from M2, which have beenplaced there by C2, then Q must, insome sense, "know" how recently thecontents of M2 have been updated.The higher the frequency of interac-tion, the more precise is the require-ment of temporal coordination.

In general, if the components of aparallel system are to operate with a

high degree of interdependence, theremust be a correspondingly adequatesystem of coordination or synchroniza-tion among them. And then the co-ordinating or synchronizing system willitself be a serially organized system. Inthe case of an organism like a humanbeing, the requirements for coordina-tion are fairly obvious. Most behaviorscall upon a considerable part of thewhole sensory and motor system fortheir successful performance. Hence,patting one's head while rubbing one'sstomach becomes feasible only underthe guidance of a supervisory synchro-nizing program. Even extreme casesof schizophrenia take the form of al-ternation, rather than parallelism, ofpersonalities.

Control HierarchyThe obvious way to govern the be-

havior of a serial processor is by ahierarchy of subroutines, with an in-terpreter capable of executing the in-structions in the proper order (Newell& Simon, 1963, pp. 380-384). Forexample, the program, "Walk thelength of a block," could consist of alist of instructions to be executed inthe following sequence:

Walk the length of a block.1. Step with left foot, then 2.2. Step with right foot, then 3.3. If end of block, do 4; if not,

dol.4. Terminate.

A similar sequence of instructionscould correspond to the program,"Cross an intersection." Now by com-bining these two programs in a largerone we could construct, "Walk to the1400 block, thus:

Walk to the 1400 block.1. Walk the length of a block,

then 2.2. Cross an intersection, then 3.

32 HERBERT A. SIMON

3. If 1400 reached, do 4; if not,dol.

4. Terminate.The interpreter in such a system

starts to execute the executive program—the program at the highest level inthe hierarchy. Each instruction in thisprogram will be, in general, a subpro-gram to be executed in the same way.Thus the interpreter must proceeddownward through the hierarchyof subprograms, or subroutines, un-til it reaches an "elementary" proc-ess that can be executed immediately.While it is doing this, it must keep itsplace in the routine it is executing ateach level of the hierarchy.

Now a system organized in this sim-ple, straightforward way is likely toreveal, in its behavior, considerablesingle-mindedness and unity of pur-pose. Whatever elementary task it isperforming at a given instant was as-signed to it by a subroutine which wasitself, in turn, called for by a higherlevel subroutine. Thus, everything thatis done is done in the service of thehighest level executive programthrough successive levels of delega-tion.

This apparently single-minded, sin-gle-purpose behavior of most existingsimulations of information-processingsystems provides a striking contrastwith human behavior. Under manycircumstances, human behavior can beinterrupted by imperative demands en-tirely unrelated to the goal hierarchyin current control—by hunger, fear,noticing sudden motion, etc. More-over, even when not actually inter-rupted, human behavior appears to beresponsive not to just one, but to amultiplicity of goals. A speaker notonly attends to the content of what heis saying, but also responds in manygross and subtle ways to the feedbackhe gets from the facial expressions and

postures of his listeners. While he isseeking to inform, he may also be seek-ing to please, to impress, or to earnlove.Goal Completion

Even in a purely serial system, theremust be some way in which a particu-lar subroutine can be terminated andcontrol returned, at the next higherlevel, to the routine that called for itsexecution. What are the criteria ofcompletion of a subgoal that mightinitiate this termination? There area number of possible alternatives:

Aspiration achievement. A subrou-tine may terminate when its subgoalhas been achieved. The subgoal maybe, for example, to discover a prooffor a certain theorem or to discovera move in a chess game that leads tocheckmate.

Satisficmg, A subroutine may ter-minate when its subgoal has beenachieved "well enough." A subroutinemay search for a course of action thatwill yield at least k dollars profit or fora chess move that will win at least apawn.

Impatience. A subroutine may ter-minate when a certain amount of timehas been used up in trying to achieveit, perhaps then selecting the alternativethat is "best so far."

Discouragement. A subroutine mayterminate after a certain set of proc-esses for attaining the subgoal has beentried and has failed.

Thus, aspiration levels, satisficingcriteria, impatience, and discourage-ment constitute mechanisms for termi-nating subroutines which can be com-bined in a variety of ways. Existinginformation-processing systems, for ex-ample, theories of problem solving inchess, already incorporate these kindsof goal-completion mechanisms.8

3 Schemes of this general kind are de-scribed in Simon (19S7, Ch. 14, 15). Some

MOTIVATIONAL AND EMOTIONAL CONTROLS

MULTIPLE GOALSEven if a system is organized in the

serial hierarchic fashion described, itmay be able to respond to several goalssimultaneously. There are at least twoways in which multiple goals can beintroduced into such a system withoutaltering basically its serial character.The first is by queuing—attending toseveral goals in sequence. The secondinvolves generalizing the notion of goalto encompass multifaceted criteriaagainst which possible problem solu-tions are tested. We shall considerthese in order.

Queuing of GoalsAt a minimum a living organism

like a human being has to satisfy, peri-odically, its biological needs. A goal(e.g., seeking food or water) is thenevoked by a drive. If the organism isquiescent at the time a new goal isevoked, a program appropriate to agoal of this kind is put into execution.If the organism is already occupiedwith achieving another goal, the newgoal may be postponed and activatedwhen the program associated with theearlier goal has been terminated.*

This scheme will accommodate anynumber of needs provided the totaltime required to realize the goals thatare evoked by drives is, on the average,a small fraction of the total time avail-able to the organism. It is necessary,also, that goals be evoked a sufficienttime before their achievement becomesessential for survival. That is, thehunger mechanism must be adapted tothe organism's storage capacity for foodand the expected length of search tofind food once the goal has been evoked.

of these mechanisms are realized in the pro-grams described in Newell, Shaw, and Simon(1963) and in Simon and Simon (1962).

4 For further discussion, see Simon (1957,Ch. 15).

If goals are evoked more or lessperiodically (e.g., the need for sleep),then the queuing system can be sup-plemented or replaced by a time-alloca-tion system: a fixed cycle of processing,with each phase of the cycle assignedto a particular goal.

These two mechanisms, queuing andallocation, are used continually by hu-man beings to reconcile the competingclaims upon their serial processing ca-pacities of the multiple needs they mustsatisfy—not only biological needs, butthe whole range of goals that charac-terize adult human existence.

Multifaceted CriteriaA goal need not be a unitary thing,

and in actual fact it seldom is. Forexample, the only behaviors a humanbeing normally regards as suitable forsatisfying hunger are behaviors thatlead to ingesting foods of culturally ac-ceptable kinds in a culturally accept-able manner. A gentleman dresses fordinner and eats with knife and forkroast beef that has been obtained in alegal way (e.g., by purchase) andtreated at high temperatures.

Achievement of a goal, then, charac-teristically calls for behavior that meetsa whole set of criteria. In fact, thereis no need to treat these criteria asym-metrically, to single out one of themand call it "the goal." We could aswell say that the gentleman's goal is todine in his dinner jacket as to say thathis goal is to satisfy his hunger.5 Thehierarchy of programs that is associ-

5 This is not to say that the set of cri-teria that specifies goal achievement maynot change from one situation to another orthat there is not some sense in which "satis-fying hunger" is a more fundamental goalthan "dining in one's dinner jacket." Weare considering here only short-run consider-ations: the set of criteria that is applied bythe goal-achievement program to determinewhen processing should terminate. For fur-ther discussion of multifaceted goals, seeSimon (1964).

34 HERBERT A. SIMON

ated with the goal will be responsive tothe whole set of criteria.

Therefore, a hierarchically organizedserial system need not single-mindedlypursue a simple goal. The chess-play-ing simulations constructed by Newellet al. (1963, p. 402) and by Simon andSimon (1962), though serial programs,take into account such goals as protec-tion of pieces, development of pieces,control of the center, and restriction ofthe opponent's mobility in selecting amove. They limit themselves, ofcourse, to considering only legal moves,and there is no reason why they couldnot take into account additional cri-teria, even aesthetic ones.

In conclusion, our review of thebasic principles of organization of ex-isting information-processing theoriesreveals that, in spite of their serialhierarchic character, they permit be-havior to respond to a multiplicity ofmotives at the same time, in agreement,at least qualitatively, with the observedfacts of human behavior. Activitytoward specific goals is terminated byaspiration, satisficing, impatience, anddiscouragement mechanisms; distincttasks may be queued or handled withinindividual time allocations; choicesamong alternatives may respond tomultiple criteria. If the behavior ofexisting models frequently appears"single-minded," as compared with hu-man behavior, this is due in consider-able part to the fact that the substan-tive content of the choice criteria hasbeen excessively simplified or ab-stracted, and not to the absence fromthe models of fundamental mechanismsthat permit multifaceted activity in thehuman being.

INTERRUPTION AND EMOTIONA serial processor can respond to

multiple needs and goals without re-quiring any special mechanisms to rep-resent affect or emotion. We can use

the term motivation, in systems likethose described, simply to designatethat which controls attention at anygiven time.6 The motivation may bedirected toward a single goal, or, morecommonly, toward multiple goals.

But this is not the whole story. Themechanisms we have considered are in-adequate to deal with the fact that, ifthe organism is to survive, certain goalsmust be achieved by certain specifiedtimes. The environment places impor-tant, and sometimes severe, real-timedemands upon the system. In a queu-ing system, for example, if a new goalis evoked, it is placed on a waiting listuntil current goal programs have beenterminated. In a mild, benign en-vironment, a leisurely response of thiskind is adequate. In the real world, itsometimes is not.

If real-time needs are to be met, thenprovision must be made for an inter-rupt system. Such a system sets tworequirements:

1. A certain amount of processingmust go on continuously, or almostcontinuously, to enable the system tonotice when conditions have arisenthat require ongoing programs to beinterrupted. The noticing processeswill be substantially in parallel withthe ongoing goal-attaining program ofthe total system, although this parallel-ism may be realized, in fact, by thehigh-frequency time sharing of a singleserial processor.

2. The noticing program must becapable of interrupting and setting asideongoing programs when real-time needsof high priority are encountered. Theprograms thus set aside may simply beabandoned, or they may be resumedafter the real-time need has been met.

Simple noticing and interruptionprograms of this general kind are al-

6 This point of view toward motivation isdeveloped at length in Taylor (1960).

MOTIVATIONAL AND EMOTIONAL CONTROLS 35

ready incorporated in some informa-tion-processing theories. EPAM, atheory of rote learning, for example,notices the turning of the memorydrum and is capable of interrupting itslearning processes to attend to the newsyllable that has appeared on the drum(Feigenbaum, 1963).

A somewhat different kind of inter-rupt system fits the hunger-thirst ex-ample mentioned earlier. For eachdrive, the drive level is an increasingfunction of the number of hours of de-privation. The need having the smallerstorage capacity will generally havethe higher time gradient. Further, athreshold for each drive determines atwhat drive level the goal becomes "ur-gent" and interrupts the ongoing pro-gram.7

Real-Time NeedsWhat are the principal kinds of real-

time needs that the interruption systemserves in human beings. We can dis-tinguish three classes:

1. Needs arising from uncertain en-vironmental events—"loud" stimuli, au-ditory, visual, or other, that warn ofdanger.

2. Physiological needs—internal stim-uli, usually warning of the impendingexhaustion of a physiological inventory.

3. Cognitive associations—-loud stim-uli evoked not by sensory events, butby associations in memory, for ex-ample, anxiety arousal.

The capacity of stimuli from thesesources to interrupt attention is acommonplace of daily experience.With respect to the first class of stim-uli, it is especially clear that they willbe more likely noticed to the extentthat they are both intense and un-expected.

T A system of this kind is described inSimon (1957, Ch. IS). More recently,Tomkins (1963) has described a system withsome similar characteristics.

Sudden intense stimuli have easilyobservable effects on behavior. Theyalso have well-substantiated effects onthe CNS. These are described atlength, for example, by Lindsley(1951). These effects produce sub-stantial disruption of the electroen-cephalogram pattern (pp. 496-500).A plausible, and not novel, interpreta-tion of these CNS effects is that theyamount to an interruption of the in-terpreter that manages the goal hier-archy; that is, they supplant the pres-ent goals with a new hierarchy. Thisinterpretation has become increasinglypopular as more has been learned ofthe role of the lower brain centers inmotivation.

Second, sudden intense stimuli oftenproduce large effects on the autonomicnervous system, commonly of an"arousal" and "energy marshaling" na-ture. It is to these effects that the label"emotion" is generally attached.8 Theweight of evidence today is that theeffects result from, rather than cause,the changes in the CNS described inthe previous paragraph. Thus, sub-stantial destruction of the connectionsof CNS with the autonomic nervoussystem does not prevent normal dis-plays of emotional behavior in animals(Lindsley, 1951, pp. 484-485).

Third, in human beings sudden in-tense stimuli are commonly associatedwith reports of the subjective feelingsthat typically accompany emotional be-havior. We shall not be particularlyconcerned here with these reports, butshall assume, perhaps not implausibly,that the feelings reported are produced,

8 "Emotion" like "learning" and other tra-ditional categories, refers to a mixed bagof phenomena, which may involve diversemechanisms. Thus, the present theory prob-ably does not account for intense aestheticemotion (e.g., which may occur while listen-ing to music) where arousal of the au-tonomic system does not stem from interrup-tion.

36 HERBERT A. SIMON

in turn, by internal stimuli resultingfrom the arousal of the autonomic sys-tem.Emotional Behavior

We see that all the evidence points toa close connection between the oper-ation of the interrupt system and muchof what is usually called emotional be-havior. Further, the interrupting stim-ulus has a whole range of effects,including (a) interruption of ongoinggoals in the CNS and substitution ofnew goals, producing, inter alia, emo-tional behavior, (b) arousal of theautonomic nervous system, (c) pro-duction of feelings of emotion. Wewill be concerned with the first of theseeffects and will largely ignore theothers.

The system comprises both perform-ance and learning processes. In theperformance system, emotion is aroused(the interrupt mechanism is activated)by sensory stimuli, memory images, anddrives. What response program willreplace the interrupted program willalso depend on the nature of the in-terrupting stimulus. The responseprogram may, and often will, activatethe autonomic nervous system, produc-ing a feeling of emotion.

As Hebb (1949, pp. 238-240, 250-258) and others have emphasized, theemotional stimulus is to be regarded asmore often interrupting than disruptingbehavior. The responses to interrup-tion are largely adaptive, either be-cause they are genetically determinedor because the adaptation has beenlearned. Interruption is not limitedto simple responses like "startle," butmay evoke an elaborate goal-orientedchain of activity (e.g., the reactions ofa trained soldier to the sound of ap-proaching aircraft).

When the emotion-producing stimuliare persistent as well as intense, theysometimes become disruptive and pro-

duce nonadaptative behavior. Thisoccurs if the stimuli continue to inter-rupt, repeatedly, the evoked responseprogram and hence to prevent an or-ganized behavioral response to the orig-inal interrupting stimulus.Learning of Emotional Behavior

Several kinds of learning can occurin relation to an interrupt system:

1. The efficacy of particular stimuliin activating the interrupt system canchange. New associations are acquiredallowing stimuli not previously effec-tive to interrupt ongoing behavior.Stimuli, on the other hand, that pre-viously had the capacity to interruptoften lose their efficacy.

2. The organism can acquire new ormodified response programs associatedwith the various interrupting stimuli.

In general, the tendency of a particu-lar stimulus to evoke emotional be-havior through interruption of ongoingbehavior decreases with repetition.For example, an unskilled bicyclist whotries to carry on a conversation fre-quently interrupts his conversation toattend to the road. With greater skill,he time-shares between the conversationand the cycling without often interrupt-ing the former. In effect the earliersingle-purpose program, with frequentinterruption, has been replaced with aprogram having the goal: "Carry onthe conversation while keeping yourbalance." As learning proceeds, notonly does the amount of interruptiondecrease, but evidences of emotional be-havior become less and less frequentand intense as well.

Similarly, the response after inter-ruption usually becomes more andmore adaptive with repetition. In theearly stages of practice, the interrupt-ing response often overcorrects, causinga new interruption. As practice pro-ceeds the response is more adequately

MOTIVATIONAL AND EMOTIONAL CONTROLS 37

controlled and usually does not cause anew interruption.

In two ways, then, we may expectlearning to reduce the emotionality ofresponse as a situation becomes morefamiliar: (a) The need for interrup-tion is reduced by incorporation ofmore elaborate side conditions in theprograms associated with ongoinggoals; (b) the response to interruptionbecomes more successfully adaptive,thus forestalling new interruptions.Hence, emotionality is associated withmeeting real-time needs, particularlythose that arise unexpectedly and inunfamiliar circumstances.

Of course learning is not always suc-cessful. If interruption occurs andreal-time needs are not met, the painfulconsequences may lead to more pre-cipitous, less adaptive responses whenthe situation recurs. Indeed, the classi-cal paradigms for producing neurosisexperimentally place excessive real-time demands on the organism.

EMOTION AND SOCIAL INTERACTIONIn human behavior, situations in-

volving interaction with other humanbeings are characteristically moreheavily laden with emotion than areother situations. A theory of emotionalbehavior, to be satisfactory, must ex-plain this connection of emotion withsocial interaction.

In general, real-time needs to re-spond to the environment arise whenthe environment can change rapidlyand unpredictably. What are the mostactive and unpredictable parts of thehuman environment?

Suddenly appearing, rapidly movingobjects, for example, flying sticks andstones, are one important class ofevents calling for interruption. Changesof environment through one's own rela-tive motion, slipping or falling, areanother.

But the most active part of the en-

vironment of man, and the part mostconsequential to him, consists of livingorganisms, particularly other men.Hence, a large part of the complexityof goals arises from the need, whileaccomplishing tasks, to attend to theresponses of other human beings and todo this in real time. Thus, the be-havior of problem-solving groups iscommonly observed as taking place attwo "levels": "task-oriented" behaviorand behavior directed toward thegroup's social-emotional needs.

The degree to which a person ex-hibits emotional behavior in social in-teraction will vary with the progressof the two kinds of learning that maymodify the interrupt system. A hu-man being, in the course of develop-ment and socialization, acquires an in-creasingly sophisticated set of cues toindicate which responses of anotherperson call for interruption of his ownongoing program. As the set of in-terrupting social stimuli grows, ceterisparibus, the emotionality of social situ-ations should increase. On the otherhand, the maturing individual alsolearns programs for anticipating (henceforestalling) interrupting stimuli andfor responding to them adaptively whenthey occur. As the behavior of otheractors becomes more predictable, theego's behavior can more readily beplanned, and the emotionality of thesituation decreases. Thus, the experi-enced salesman finds his interactionwith the customer less stressful as hisability to predict responses to his ownbehavior improves.

Since the one type of learning tendsto increase the emotionality of socialsituations and the other tends to de-crease it, and since both types of learn-ing can be expected to go on simul-taneously, the theory leads to no defi-nite prediction of whether, netting thesetwo effects, emotionality of social in-teraction will tend to grow or decline

38 HERBERT A. SIMON

for the individual. Common observa-tion suggests that it typically growsthroughout adolescence, then gradu-ally declines throughout adult life.

MOTIVATION AND LEARNINGLearning theories differ widely in

the role they assign to motivation in thelearning process. These differenceswere central to the controversy, in the1930's and 1940's, about latent learn-ing. The issue in its simplest formis whether the organism learns any-thing about aspects of its environmentthat are not directly relevant to itscurrently evoked goal system. Forlabeling purposes only, let us call theaffirmative and negative views on thisquestion Tolmanian and Hullian, re-spectively.

The theory proposed here gives aqualified Tolmanian answer to thequestion and predicts some circum-stances under which latent learning willoccur. When we try to make orderout of the chaos of latent learning ex-periments, as Kimble, Hilgard, andMarquis have done (Kimble, 1961, pp.226-234), we discover that they arereasonably consistent with the two fol-lowing generalizations:

1. Learning only occurs when thereis knowledge of results, but may pro-ceed in the absence of any obvious re-ward or punishment, Punishment isoften as effective in giving knowledgeof results as is reward.

2. Learning without obvious punish-ment or reward occurs principally un-der conditions of low irrelevant drive.

The simplest explanation of thesefacts is that motivation is effective pri-marily in determining what goal hier-archy will be activated at any giventime; hence it is effective in determin-ing what aspects of the environmentwill be relevant to the organism forperformance of learning. Stated other-

wise, motivation controls attention andhence influences learning only throughits influence on program control.Given the focus of attention and theestablished goal hierarchy, learningstill requires knowledge of results, butdoes not call for reward or punishmentmechanisms. Reward and punishment,and motivation generally, install andreplace goal systems.

This explanation leads to three pre-dictions of circumstances under which"latent" learning will occur. First, ifwhile achieving a particular evokedgoal the organism encounters an in-terrupting stimulus, it may learn thingsthat are irrelevant to the original goal,but relevant to the response programactivated by the interruption. Thus,a hungry rat can learn where it willreceive an electric shock in the maze.But by increasing the intensity of theoriginal drive, we should be able to re-duce sensitivity to interruption andhence reduce the amount of learningproducible by potentially interruptingstimuli. The fact that the interruptingstimulus does or does not have punish-ment associated with it is irrelevant.

Second, as goals are elaborated bythe incorporation of side constraints,the organism will learn about aspectsof the environment that are relevant tomeeting the side constraints, as well asaspects relevant to the original goal.Thus, as a novice chess player beginsto learn that he must protect his ownmen while attacking his opponent's,he learns to attend to his opponent's aswell as to his own threats.

Third, really a generalization of thefirst two points, the organism may learnabout any aspect of the environmentthat "happens" to attract its attention.Aspects of the environment with whichnegligible, or no, rewards and punish-ments are associated will generally at-tract attention only when other, morepressing needs are absent. Hence,

MOTIVATIONAL AND EMOTIONAL CONTROLS 39

consistent with the evidence, latentlearning should occur principally un-der conditions of low irrelevant drive.

CONCLUSIONThis paper has proposed a theory of

the relation of motivation and emo-tional behavior to man's information-processing behavior. The theory ex-plains how a basically serial informa-tion processor endowed with multipleneeds behaves adaptively and survivesin an environment that presents unpre-dictable threats and opportunities. Theexplanation is built on two centralmechanisms:

1. A goal-terminating mechanismpermits the processor to satisfice, deal-ing generally with one goal (albeit per-haps a complex one) at a time, andterminating action when a satisfactorysituation has been achieved.

2. An interruption mechanism, thatis, emotion, allows the processor to re-spond to urgent needs in real time.

Rudimentary mechanisms of thesekinds have already been incorporatedin some of the current information-processing theories of human cognition.Elaboration of the mechanisms and as-signment to them of a larger and morecrucial role in the simulated behaviorwill permit these theories to be ex-tended to the explanation of widerranges of human behavior. Thus, in-formation-processing theories must beendowed, as can readily be done, withthe properties that Neisser lists ascharacterizing human thinking: inti-mate association of cognitive processeswith emotions and feelings, and deter-mination of behavior by the operationof a multiplicity of motivations oper-ating simultaneously.

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(Received December 3, 1965)