JOURNAL OF THE EXPERIMENTAL ANALYSIS OF BEHAVIOR

A CLASSIFICATION AND REVIEW OFCOOPERA TION PROCEDURES1

DON F. HAKE AND RON VUKELICH

ANNA STATE HOSPITAL

The definition of cooperation allows many procedural variations, as revealed by examina-tion of the cooperation literature which includes procedures differing so greatly that it issurprising that all of them are considered under the same topic. This paper attempts toprovide a framework for organizing that literature by (1) indicating some proceduraldimensions along which cooperation procedures can be classified, (2) classifying and re-viewing briefly the research at the extremes of these procedural dimensions, and (3) indi-cating the behavioral effects that are necessary to demonstrate control by the variouscooperation procedures.

I. DEFINITION OF COOPERATIONThe essential aspects of any cooperation pro-

cedure are (1) that the reinforcers of bothindividuals are at least in part dependentupon the responses of the other individual,and (2) that the procedure allows such re-sponses, designated as cooperative responses,to result in an equitable division of responsesand reinforcers. An increase in cooperative re-sponses is indicative of a cooperation effect.The basic procedural requirements allow con-siderable variation, as shown by the coopera-tion literature, in which procedures are in-cluded that differ so greatly it is surprisingthat all of them are considered under the sametopic. With deference to such an impression,the present paper indicates some dimensionsalong which cooperation procedures can beclassified, classifies and reviews briefly the re-search at the extremes of these proceduraldimensions, and indicates the behavioral ef-fects that are necessary to demonstrate controlby the various cooperation procedures.

1This work was supported by the State of IllinoisDepartment of Mental Health and NIMH Grant 17981.As his cooperative response in a long-standing historyof response-exchange cooperation with the first author,Dr. Harris Rubin came through as usual with valuablecriticisms of the manuscript. The authors are also in-debted to Mr. Sheldon Kaplan who provided valuableassistance at several points in the preparation of thismanuscript. Reprints may be obtained from Don F.Hake, Behavior Research Laboratory, Anna State Hos-pital, Anna, Illinois 62906.

II. THE BASIC PROCEDURAL UNIT:AN EPISODE OF COOPERATIVE

RESPONDING

The obvious place to begin classifying co-operative procedures is the basic proceduralunit that gives the minimal response require-ment for reinforcement. This basic proceduralunit will be designated as the cooperative epi-sode, and refers to all of the responding, in-cluding at least one cooperative response, thatis required for the delivery of a reinforcer. Acooperative episode may require responsesfrom both individuals or from only one indi-vidual, it may include reinforcement forboth or for only one of the individuals, itmay include an equitable or an unequitabledistribution of work and/or reinforcers, butit must include at least one cooperative re-sponse and one reinforcer. Simply, wheneverthere has been enough responding, includ-ing at least one cooperative response, toresult in the delivery of a reinforcer, thebasic procedural unit has been completed.The definition of cooperation requires thepossibility of an equitable distribution of workand/or reinforcers; hence, if an equitable dis-tribution cannot be reached in a single epi-sode, but only over several episodes, time mustbe allowed for the occurrence of several epi-sodes. The entire time allowed for cooperativeepisodes to occur will be designated as thecooperation period.

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1972, 18, 333-343 NUMBER 2 (SEPTEMBER)

DON F. HAKE and RON VUKELICH

III. CHOICE AND PERFORMANCEPROCEDURES

All cooperation research can be placed intotwo major categories, which will be designatedas performance procedures and choice proce-dures. Performance procedures measure thebehavior that occurs during the carrying outof a cooperative solution or, in other words,the cooperative behavior itself. On the otherhand, the choice procedures measure only theselection of a solution: they do not measurethe behavior required to carry out a solution.In choice procedures, such as the Prisoner'sDilemma game (see review by Nemeth, 1970),there are several alternative solutions tochoose from, including one in which rein-forcers are equally distributed (cooperation)and one in which reinforcers are unequallydistributed (competition). This paper is con-cerned with classification of procedures thatmeasure the behavior that occurs during theactual carrying out of a cooperative solution,and thus deals with performance procedures.

Experiments can include both choice andperformance procedures. For example, the re-cent experiments of Schmitt and Marwell(1971a, 1971b) included a choice procedure inthat the clhoice of a cooperative or individualsolution to a task was measured. The experi-ments included a performance procedure inthat the behavior that was necessary to com-plete the cooperative solution was also mea-

sured. The cooperative solution required firstthat one subject pull his plunger and producea 3-sec stimulus light, and then that the othersubject pull his plunger within 0.5 sec aftertermination of the stimulus; when this per-

formance occurred, the behavior of both sub-jects was reinforced. For individual respond-ing, only a single pull of the plunger was rein-forced. Whenever an experiment, such as theabove, includes objective measurement of bothchoice and performance, that procedure willbe categorized under performance procedure.

IV. PROCEDURAL DIMENSIONSALONG WHICH PERFORMANCEPROCEDURES CAN BE CLASSIFIED

A. Dependency upon Behavior of Partner forReinforcement

1. Interdependent cooperation procedures.In any cooperation procedure, the reinforcers

of each individual must be at least in part de-pendent upon the responses of the partner, butthe extent of this dependency can vary. At oneend of the continuum, an individual's rein-forcers can be largely dependent upon his ownbehavior and only slightly dependent uponthe behavior of his partner. At the other endof the continuum, an individual's reinforcerscan be largely or even completely dependentupon the behavior of his partner. Wheneverthe responses of both individuals are necessaryfor, or can affect, the reinforcers of one indi-vidual, the cooperation procedure will bedesignated as interdependent. On the otherhand, when the reinforcers of a given individ-ual are completely dependent upon the re-sponses of the partner, the cooperation pro-cedure will be designated as dependent. All ofthe cooperation studies under the performanceprocedure are classified as either interdepen-dent or dependent in Table 1. Table 1 alsoclassifies these studies at one of the two ex-tremes of three other procedural dimensionsdiscussed in this paper. The table is organizedinto an ordered arrangement of the 12 logi-cally possible combinations of these classifica-tions (out of 16 possible), thereby allowing thestudies to be further classified under one of the12 combinations.Rosenberg and Hall (1958) and Rosenberg

(1959, 1960) used a cooperation procedure thatvaried the extent to whiclh each subject's rein-forcers were dependent upon the responses ofa partner. For example, the cooperation pro-cedure was interdependent when both sub-jects' reinforcers depended on the number oftimes both subjects turned their response dials.At times, a high percentage of a subject's owndial turns, but only a small percentage of hispartner's, counted toward his response require-ment for reinforcement. Hence, the reinforcersof a given subject were largely dependent uponhis own responses. At other times, the percent-ages were reversed so that the reinforcers de-pended more on the responses of his partnerthan on his own responses. And, finally theprocedure was dependent when each subject'sreinforcers were entirely dependent upon thepartner's responses.

In the preceding interdependent coopera-tion procedures, both subjects responded byturning a dial. In everyday life, however, in-terdependent cooperation frequently consistsof different responses by each of the individ-

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Table 1

Classification of cooperation studies under one of the two classifications on eachof the four procedural dimensions, and under one of the twelve logically possiblecombinations of the classifications.

Procedural Dimensions Studies Subjects

(1) (2) (3) (4)

N S0 0N C FFORCED - Lindsley (1966) Children, Adults

AL ALT. RESP. No Studies

Cohen (1962): Children, AdultsLindsley (1966)

R Azrin 6 Lindsley (1956):E Brotsky 6 Thomas (1967):S Vogler (196R)! Nelson fi Childrenp Madsen (1969); Stewart.o Zelman 6 Mithaug (1971)NES S FORCED Schmitt 6 Marwell (1968) College StudentsE S

0 Hollis (1966) Retarded Childrens C

I H I. Hingtgen 6 Trost (1966) Autistic ChildrenN A AT R L Peters 6 Murphree (1954)E I King, Armitage 6 Tilton Mental PatientsR N (1960)D GE Crawford (1941) ChimpanzeesPE Schmitt 6 MarwellN (1971 a 6 b) College StudentsD Marwell, Schmitt FE ALT. RESP. Shotola (1971)NT Mithaug 6 Burgess (1967, Children

1968): Mithaug (1969)

R N SE O 0 FORCED Rosenberg & Hall (1958)! Air Force TraineesS N C Rosenberg (1959, 1960)

O AN L ALT. RESP. No StudiesSE Rosenberg (1963) College Students

E S Weingold f. Webster (1Q64) Childrenx C Hingtgen, SanderstuitcCideC

C FORCED DeMyer (196S) Autistic Children

N A Boren (1966) Macaque MonkeysG Daniel (1942, 1943): RatsE Taylor 6 Erspamer (1971)

ALT. RESP. Hake 6 Vukelich (unpublished) Retarded Patients

R Sidowski, Wyckoff 6E N S Tabory (1956); Sidowski College Students5 0 0 FORCED (1957)

Dp N C Rosenberg

6Hall (1958): Air Force Trainees

E N A Rosenberg (19S9,1960)

E ES LN E _ ALT. RESP. No StudiesD

E S Sidowski (1957) College StudentsN C 0T H c FORCED Hiollis (1966) Petarded Children

A IN A Boren (1966) F'acaque M4onkeys

LE ALT. RESP. Hollis (1966)

Note. Procedural dimensions and classifications at the extremesof each dimension(1) Dependency on partner for reinforcement: Interdependent or Dependent(2) Deviations from reciprocity: Response Sharing or Pesponse Exchange(3) Partner as social stimulus: Non-Social or Social(4) Alternative non-cooperative response: Forced or Alternative Response

Of the 16 possible combinations of classifications, only 12 are logicallypossible. A response-sharing procedure by definition cannot involve a dependentprocedure thereby eliminating 4 combinations. A given study may appear undermore than one of the twelve combinations since it may have included more thanone of the procedural combinations.

DON F. HAKE and RON VUKELICH

uals because it is often necessary or more con-venient for the individuals to work on dif-ferent parts of the response requirement.Consider, for example, the work of a locallawn-mowing service. One worker operates themower while another worker trims the yardand rakes the cut grass. Each worker respondsdifferently; together, they efficiently completethe requirement for reinforcement. The classicprocedure of Daniel (1942, 1943) is an exampleof an interdependent cooperation procedurein which the subjects (rats) made different re-sponses. During an episode of cooperative re-sponding, one rat terminated aversive grid-shock by sitting on a platform while a secondrat ate from a food bowl placed on the gridfloor. The procedure was interdependent inthat the responding of both rats was requiredfor an episode of cooperative responding.Nor does the cooperation procedure have to

be the same for both members of a partner-ship. For example, the reinforcers of one in-dividual can be completely dependent uponthe responses of his partner, while the rein-forcers of the partner are dependent upon theresponses of both individuals. This proceduremay be called an asymmetrical cooperationprocedure. Similarly, the procedure for a givenindividual can change from dependent to in-terdependent from one episode of coopera-tive responding to the next.

2. Dependent cooperation procedure. Fewstudies have made a subject's reinforcers en-tirely dependent upon the responses of hispartner (see Table 1). Boren (1966) requiredone monkey to press a lever 32 times to delivera reinforcer to a partner, another monkey visi-ble in an adjacent chamber. Similarly, thefirst monkey received a reinforcer only whenthe partner reciprocated by pressing a lever32 times. In the studies of Sidowski, Wyckoff,and Tabory (1956) and Sidowski (1957) collegestudents received points only when their part-ners pressed a particular button. Each subjecthad two response buttons; the operation ofone delivered points to the partner and theoperation of the other delivered shocks to thepartner.

B. Deviations from Reciprocity1. Response-sharing procedure. As used

here, reciprocity refers to an equal distributionof responses and reinforcers between two par-ticipants on a given episode of cooperative

responding or over an entire period of cooper-ation. Deviations from reciprocity, therefore,will refer to inequities in the distribution ofresponses and/or reinforcers on an episode ofcooperative responding or over an entire co-operation period. Since reciprocity is definedas an equal distribution of responses and re-inforcers, reciprocity on each episode of co-operative responding can occur only in aninterdependent cooperation procedure that re-quires the same response from and deliversthe same reinforcer to each partner in eachcooperative episode. Procedures that requirereciprocity on each episode of cooperative re-sponding will be designated as response shar-ing. As an example of a response-sharing pro-cedure from everyday life, consider twoindividuals who have the assignment of carry-ing heavy barrels from one place to another.The barrels are so heavy that both individualsare necessary to carry one. In this example,there is an interdependent cooperation con-tingency in which both individuals make thesame response and both receive the same rein-forcers.A response-sharing procedure frequently

used in the laboratory is that of Cohen (1962)and Lindsley (1966), which is a modified ver-sion of Azrin and Lindsley (1956), and Skinner(1953, p. 306). (See Table 1 for other response-sharing procedures.) Under the basic Lindsley(1966) procedure, two subjects visible to eachother through a window between their com-partments, each receive a reinforcer when theypull their response plungers within 0.5 sec ofeach other. Since each episode results in reci-procity, in terms of both the workload and thedistribution of reinforcers, the procedure maybe designated as response sharing.

2. Response-exchange procedures. Proce-dures that do not require an equitable dis-tribution of reinforcers or responses during anepisode of cooperative responding will be des-ignated response-exchange procedures. Sincereciprocity is not required, the cooperationprocedure can be dependent or interdepen-dent (see Table 1), either one or both of theindividuals can receive reinforcers during anygiven episode, and deviations from reciprocitycan be in terms of the responses or reinforcers.Reciprocity, of course, is still possible underthese procedures, but it requires responses andreinforcers to be equalized over the period ofcooperation, rather than during a cooperative

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CLASSIFICATION OF COOPERATION PROCEDURES

episode as in response sharing. In actuality,such a procedure is not unusual and one formmight be characterized as: "I will do the workthis time, you do it next." Thus, a man whomows his neighbor's lawn is probably not be-having altruistically; rather, he is probablyresponding as a result of a previous history inwhich the two individuals have exchangedcooperative episodes under a response-ex-clhange procedure.

Response-exchange procedures have variedin the extent to which they allow deviationsfrom reciprocity. Some are similar to the re-sponse-sharing procedure in that deviationsare severely limited. For example, Hingtgen,Sanders, and DeMyer (1965) used an interde-pendent cooperation procedure in which anepisode of cooperative responding consisted ofone subject activating the apparatus of hispartner who could then respond and producea reinforcer for himself. The procedure wasresponse exchange in that cooperative episodesresulted in deviations from reciprocity, butbecause strict alternation of cooperative epi-sodes was required, the duration and extent ofthese deviations was severely limited. In an-other experiment, Hollis (1966, Experiment 2)studied the cooperative behavior of retardedchildren using a Wisconsin General Test Ap-paratus (WGTA) modified for use with twosubjects. Each session consisted of 24, 1-mintrials during which each subject could pull ahandle to extend a baited cart to his partner.The extent of the deviations from reciprocitywas restricted by the limit put on the absolutenumber (24) of cooperative episodes of eachsubject during each session. This "trials" pro-cedure can be contrasted to the free operantprocedure of Boren (1966, second procedure),where no limits were placed upon the rate ofcooperative episodes or the deviations fromreciprocity. In that dependent cooperationprocedure, the fixed-ratio responding of onemonkey resulted in reinforcement for theother and vice versa.

Hollis (1966) and Boren (1966) used depen-dent cooperation procedures in which cooper-ative episodes deviated from reciprocity interms of the distribution of both the workloadand the reinforcers. Dependent cooperationprocedures can also be arranged so that onlythe workload deviates from reciprocity duringa cooperative episode. For example, Hollis(1966, Experiment I) altered the WGTA to

allow each subject the choice between deliver-ing a baited cart only to himself, or workingthe task cooperatively by extending two baitedcarts, one to his partner and one to himself.(On alternate sessions, his partner had thesame choice.) In this procedure, the only de-viation from reciprocity during a cooperativeepisode was in the workload.

Interdependent cooperation procedures canalso allow deviations from reciprocity (seeTable 1). Large deviations are especially pos-sible when the procedure allows only one sub-ject to receive reinforcers on each cooperativeepisode. For example, in Daniel's (1942, 1943)procedure, one rat sat on a platform, therebyterminating grid shock and allowing the otherrat to stand on the grid and eat from the foodbowl. Since only one rat could eat withoutbeing shocked, there could be large deviationsfrom reciprocity on each cooperative episode.And, since this was a free operant study, therewere no limits upon the extent of the devia-tions, allowing the possibility of only one ratobtaining food during a session. Deviationsfrom reciprocity can also result when an epi-sode of interdependent cooperative respond-ing produces reinforcers for both subjects.For example, the reinforcers could differ forsubjects on each episode in Rosenberg's (1963)procedure, where the reinforcers were a func-tion of the number of dial turns made by eachsubject. For a given subject, a percentage ofhis own responses (e.g., 60%) and a percentageof his partner's responses (e.g., 40%/) countedin determining his reinforcers. When thesesame percentages were in effect for the partner,there could be deviations from reciprocitywhenever the subjects turned their dials a dif-ferent number of times on a cooperative epi-sode.

C. The Partner as a Social Stimulus1. Non-social procedures. In non-social pro-

cedures, precautions are taken to prevent sub-jects from learning that the reinforcers deliv-ered to them are at least in part dependentupon the responses of another subject or thatthere is another subject in the experiment.The rationale is that the main factors control-ling social behavior are the laws of condition-ing for individual subjects, rather than thecomplex variables introduced by social inter-action. Sidowski, Wyckoff, and Tabory (1956)and Sidowski (1957) assumed the major factors

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controlling social behavior to be reward andpunishment. Sidowski described the essentialfeatures of the social situation as follows: "(a)Two or more subjects have at their disposalresponses which result in rewarding or punish-ing effects on other subject. (b) The principalsources of reward and punishment for anysubject depend on responses made by theother subject. (c) The responses controllingreward and punishment are subject to learn-ing. It will be assumed that whatever elsemay be involved, at least the above features arepresent in any social situation" (Sidowski,1957, P. 318). In one study, subjects were di-vided into an "informed" group, in which thesubjects were told that another subject wasserving in the experiment, or an "unin-formed" group, in which subjects were nottold that they were in a social situation. Thetwo members of a pair were tested at the sametime but in separate rooms, in which the onlysources of interaction were two buttons. De-pending upon their subgroup and which but-ton was pressed, they could give each otherpoints, points or shock, or shock alone. Whenthe subjects could give each other points, orpoints or shock, cooperative responses in-creased over time: subjects soon learned topress the button that delivered points to theirpartners, regardless of whether they even knewthey had a partner.

2. Social procedures. Under social coopera-tion procedures, the subjects are typicallytested in full view of one another, and areeither told about the social relationship or pre-sumably learn it. Such procedures are con-sidered important because (1) cooperative be-havior is observed to occur under similarconditions in everyday life and, (2) social stim-uli may produce behavioral changes that arenot easily produced under non-social proce-dures or explained by the laws of conditioningfor individual subjects.

In any social situation, it is difficult to sep-arate the social stimuli that are affecting be-havior from non-social stimuli that may besimultaneously affecting the behavior. Manystudies of social cooperation ignore the possi-ble effects of non-social stimuli and assumethat the existence of cooperative respondingindicates behavioral control by the social re-lationship. This, of course, is in direct contrastto the work of Sidowski (1957) discussed in theprevious section.

Behavioral changes that are attributable ex-clusively to social stimuli have been called"social emergents" and are considered ofutmost importance in social psychology(Lindsley, 1963, 1966). For example, socialfacilitation (an increase in a behavior of oneindividual as a result of the presence of an-other individual) is, by definition, a basic so-cial emergent. Studies concerned with the so-cial facilitation of feeding, the response mostfrequently studied, have shown that the in-crease in behavior cannot be attributed tonon-social mechanical stimuli, such as theactivation of the co-actor's food tray (e.g.,Hake and Laws, 1967; Hake, Powell, andOlsen, 1969).Few studies have isolated social emergents

effectively enough to evaluate their effect uponcooperative behavior. In a classic study, Linds-ley (1966) compared cooperative behaviorunder several social and non-social conditions.Subjects were placed in individual experi-mental chambers, and each chamber containedlights and buzzers that signalled responsesand/or the delivery of reinforcers. In addition,the experimenter could uncover a transparentpartition between the chambers and thus per-mit the subjects to observe each other. A co-operative episode was defined as either sub-ject pulling a response plunger within 0.5 secof the other. The order in which the subjectswere required to respond, designated as a lead-ership requirement, could be varied so thateither Subject A or Subject B might be re-quired to respond first and thereby be theleader. The subject could be tested underthree basic conditions:

(1) Non-social, in which the partition wascovered and the only information availablecame from the lights and buzzers.

(2) Social, in which the partition was un-covered and the subjects could see and signaleach other, as well as use the informationavailable from the lights and buzzers.

(3) "Quasi-social", in which subjects werefirst exposed to the social condition and thentested on the non-social condition. The termquasi-social is ours and is used to indicate me-chanical stimuli such as lights and soundswhich, due to previous experience or instruc-tions, are known to be produced by anotherindividual. The quasi-social stimuli in thisexperiment are comparable to some mechani-cal stimuli seen in everyday life such as signs,

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CLASSIFICATION OF COOPERATION PROCEDURES

letters, and porch lights. Quasi-social stimuliare included in Lindsley's (1963, 1966) termsocial connotation, but social connotation alsoappears to include social stimuli (e.g., Linds-ley, 1966).Although cooperative responding was

learned under non-social conditions, learningwas faster under both the social and quasi-social conditions. In addition, when the socialand quasi-social conditions were compared, itwas found that the sight of the partner in-fluenced the determination of who was to bethe leader.

D. Alternative non-cooperative responses1. Forced cooperation. Cooperation proce-

dures that. do not allow an alternative non-cooperative response that will produce thesame reinforcer as the cooperative responsewill be designated as "forced" cooperation, be-cause the only alternative to cooperation isdoing without the reinforcer. As shown inTable 1, most cooperation research under theperformance procedure has involved forcedcooperation.

2. Alternative-response procedures. Cooper-ation procedures can involve both choice andperformance procedures, as is the case whenthe same reinforcer can be obtained by eithercooperative or non-cooperative responses.This is frequently the arrangement in dailylife, when individuals cannot depend upon theavailability of a cooperative partner. Mithaug(1969) reported one of the few studies in whichan alternative, non-cooperative response pro-duced the same reinforcer as the cooperativeresponse. A cooperative episode involved a re-sponse-sharing procedure in which each of thethree subjects was required to pick the correctresponse key from among 14 possibilities, andthen respond within 0.5 sec of the others. Oncethe correct key was found, the subjects couldcontinue responding throughout each 30-sectrial. Alternative, non-cooperative responseswere simply individual responses that did notmeet the 0.5-sec requirement for coordinatedresponding but were effective in producingthe same reinforcer. Subjects typically chosethe individual response, but preference couldbe shifted from individual to cooperative re-sponding by raising the number of individualresponses required for reinforcement.Hake and Vukelich (unpublished study)

also provided individual and cooperative solu-

tions for subjects who were each workingmatching-to-sample problems. For each sub-ject, reinforcement was contingent upon re-sponses on each of two different panels. Thefirst response, on one panel, was a buttonpress that produced a sample stimulus on thatpanel. The second response, on the otherpanel, was the pressing of the button corres-ponding to the matching stimulus on thispanel. Each subject had both a sample paneland a matching panel. The matching panelsof the two subjects were located at oppositeends of the room 6 m apart, but a subject'ssample panel could be placed at different dis-tances from his matching panel. As long aseach subject's sample panel was next to hismatching panel, subjects worked the problemsindividually. However, when the sample panelof Subject A was next to the matching panelof Subject B, and the sample panel of SubjectB was next to the matching panel of Subject A,the subjects produced the sample stimuli foreach other and then made the matching re-sponse for themselves. In order to work thematching task individually, subjects wouldhave had to walk the length of the room, pro-duce their own sample stimulus, and then re-turn to their matching panel to make thematching response. The relative response re-quirement for individual and cooperative solu-tions could be varied by systematically manip-ulating the distance of each subject's samplepanel from his response panel, e.g., the sam-ple panels of both subjects could be placed inthe middle of the room or at any proportion ofthe distance to the other subject. The subjectsalways selected whichever solution involvedthe least amount of walking.

Alternative responses can take many formsand more than one may be available in a co-operative procedure. In the Prisoner's Di-lemma game, as well as other game-playing(typically choice) procedures, subjects canmake competitive as well as cooperative re-sponses. Schmitt and Marwell (1971a), usinga performance procedure, allowed their sub-jects to select cooperative or individual solu-tions. A third alternative, taking points awayfrom the partner, was permitted when a speciallight was illuminated. The subjects generallychose to avoid the stimulus for taking by se-lecting the solution, cooperative or individual,during which this stimulus was presentedleast often. Obviously, the inclusion of alterna-

DON F. HAKE and RON VUKELICH

tive responses such as these, or others, candrastically affect the probability of cooperativeresponding.

V. DEMONSTRATION OFCONTROL BY THE COOPE,RATION

PROCEDUREThe essential aspects of any cooperation

procedure are that the reinforcers of both in-dividuals be at least in part dependent upon

the responses of the other individual, and thatthe procedure allows such responses, desig-nated as cooperative responses, to result in an

equitable division of reinforcers and responses.

The essential aspect of a cooperation effect isan increase in cooperative responses. However,as with other behavioral phenomena, the mere

increase in a given behavior does not neces-

sarily indicate that the behavior was underthe control of the procedure. For example, ifthe rate of a response increases when it hasbeen consistently followed by the delivery ofa stimulus, this does not necessarily mean thatthe stimulus meets the definition of an operantreinforcer. To conform to this definition, theincrease must be due to the specified operantprocedure, rather than elicited effects of thestimulus, another reinforcer, or another pro-cedure. Several studies of cooperation havebeen weakened because they failed to demon-strate that the observed cooperative-like behav-ior was actually under control of the coopera-

tion procedure rather than some other socialor individual procedure. A reciprocal rein-forcement procedure is more complex thanreinforcement with only one individual; con-

sequently, it is more difficult to show thatcooperative-like behavior is under the controlof the cooperation procedure. Demonstrationof control by a cooperation procedure requiresdemonstration of control by (a) the reinforcerresulting from the cooperation procedure and(b) the specified procedural relation betweenresponses and reinforcers.

A. Control by the reinforcer resulting fromthe cooperation procedure

If cooperative-like responding is under thecontrol of the cooperation procedure, thatresponding should be maintained by the re-

inforcer resulting from the cooperation proce-

dure, rather than by any other reinforcer. Forexample, consider Taylor and Erspamer's

(1971) study, in which two rats separated by ahardware cloth partition "cooperated" forfood reinforcement. The two rats were con-nected by a string that passed througlh holes atthe back of the experimental chamber, andthat was long enough so that only one rat ata time could be at the front of the chamberwhere the food trays were located. The coop-erative response of going to the back of thechamber could have been produced by severalfactors in addition to the food reinforcement:cooperative-like responses could have beenmaintained by avoidance of the discomfortresulting from the "hungrier" rat pulling onthe string, or one rat could have been literallydragged to the back of the chamber by thepulling of the "hungrier" rat. The question iswhether the cooperative-like responding wasmaintained by food reinforcement, by an in-dividual avoidance procedure, or simply bythe other animal's food responses. In the lat-ter two cases, going to the back of the chambercould not be considered cooperative.Demonstration of control by the reinforcer

produced by cooperation would appear to beparticularly important in studies using humansubjects and allowing verbal interactionbetween them. Is the cooperative-like re-sponding of a given subject maintained byinstructions from the partner and the possiblenegative consequences of not following theinstructions? In such a case, the cooperative-like behavior of the subject would be main-tained at least in part because following in-structions avoids aversive consequences.

B. Control by the specified proceduralrelation between responses and reinforcers

In single-subject experiments, control by theprocedural relationship between responses andreinforcers is indicated by an increasing cor-respondence between the observed responsesand reinforcers and the procedural require-ment between responses and reinforcers. Forexample, in complex individual proceduressuch as the fixed-interval schedule of reinforce-ment, not only does the rate of respondinggradually increase, but there is also a gradu-ally increasing correspondence between theobserved responses and the response require-ment, i.e., a higher percentage of responsesoccur near the end of the fixed-interval whereresponding is reinforced. The manner inwhich procedural control is demonstrated for

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CLASSIFICATION OF COOPERATION PROCEDURES

cooperation depends upon whether coopera-tion is considered under a social or a non-so-cial procedure. First, consider cooperation as asocial process where the procedural relation-ship between responses and reinforcers is re-ciprocal reinforcement. The best indicationsof control by reciprocal reinforcement appearto be (1) that the cooperative behavior of eachsubject is under the control of the cooperativebehavior of the other subject, and (2) that thecooperation procedure increases the numericalcorrespondence between the responses and/orthe reinforcers of the two subjects. These twotypes of control would be indicative of thesocial and reciprocal nature of the cooperativebehavior.The way to show that the cooperative be-

havior of each subject is under the control ofthe cooperative behavior of his partner willdepend upon whether both (e.g., interdepen-dent, response sharing) or only one (e.g., de-pendent) of the subjects make a cooperativeresponse during each episode of cooperativeresponding. As an example of an interdepen-dent, response-sharing procedure, consider theprocedure of Lindsley (1966) and Cohen (1962)in which the reinforcers of both subjects weredependent upon the subjects pulling their re-sponse plungers within 0.5 sec of each other.Under this procedure, the question is whetherthe resulting high rates of cooperative-like re-sponding are under the control of the coop-erative behavior of the partner or are underthe control of an individual, high-rate con-tingency. For example, a steady response rateof 120 responses per minute by each subjectwould result in many reinforced or coopera-tive-like responses. If the responding wereunder the control of an individual high-ratecontingency, individual responses that did notmeet the 0.5-sec criterion for coordinated re-sponding would be expected to increase andto be maintained along with responses meetingthe 0.5-sec criterion (Brotsky and Thomas,1967; Vogler, 1968; Schmitt and Marwell,1968). On the other hand, if a subject wereunder the control of the cooperative behaviorof his partner, individual responses would beexpected to decrease to a near-zero level, leav-ing only those responses that met the 0.5-secrequirement for cooperative responses. Todemonstrate this type of social control forboth subjects, the leader-follower requirementswould have to be varied, so that at times the

responses of Subject A had to follow those ofSubject B and at other times, the responses ofSubject B had to follow those of Subject A.

It is more difficult to demonstrate that thecooperative behavior of a subject is under thecontrol of the cooperative behavior of hispartner in dependent cooperation procedures.It is simply unrealistic to expect that subjectswill always respond in strict alternation suchthat the cooperative response of one subject isalways the stimulus for the next cooperativeresponse of his partner. For example, considertwo cooperative neighbors exchanging favors.There may be instances in which neighbor Amight do several favors for neighbor B beforeneighbor B reciprocates. The neighbors maynot pay back the favors after each cooperativeresponse; rather, as in this example, recipro-city would be reached over a period of timeor over several cooperative responses. In anexperimental setting, however, it would be aneasy matter to determine whether or not thecooperative responding of each subject wasunder the control of the partner as a socialstimulus by systematically manipulating thepresence and absence of each subject. Controlby the partner as a social stimulus would beindicated if (1) a subject stopped respondingand/or switched to individual responding im-mediately upon the removal of his partnerfrom the situation and (2) resumed cooperativeresponding upon the return of the partner.Control by the actual cooperative respondingof the partner would be more difficult to dem-onstrate because it would necessitate leavingboth subjects in the situation and providingthe reinforcers of Subject A at the usual rate,even tlhough Subject B had stopped respond-ing. Then, if Subject A also stopped respond-ing, it would indicate that his cooperativeresponding was under the control of the co-operative responding of Subject B.The reciprocal nature of cooperative behav-

ior would be indicated (1) when the corre-spondence between the number of reinforcersand/or responses of the two subjects is higherduring cooperation than during an individualresponding procedure (Hake and Vukelich, un-published study) or (2) when the correspond-ence is higher after cooperative respondinghas stabilized than at the introduction of thecooperation procedure. It would be difficultto make a case for control by a reciprocal. as-pect of a cooperation procedure for procedures

341

342 DON F. HAKE and RON VUKELICH

(response sharing) that never allow deviationsfrom reciprocity.

Non-social cooperation procedures attemptto prevent the subjects from learning that thereinforcers delivered to them are at least inpart dependent upon responses of a partner orthat there is another subject in the experi-ment. As a result, the cooperative behavior ofboth subjects should be under the control ofthe laws of conditioning for individual sub-jects, rather than the social nature of the pro-cedure. Control by the laws of conditioningfor individual subjects would be indicated (1)by showing that each subject learned to re-spond in such a way as to maximize his prob-ability of reinforcement and (2) by showingthat the rate of cooperative responding and/orother choices was a function of the rate of rein-forcement scheduled for those responses bythe partner (see Sidowski, 1957).

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CLASSIFICATION OF COOPERATION PROCEDURES 343

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Received: 11 September 1971Final acceptance: 8 May 1972