group polarization isenberg

Journal of Personally and Social Psycholog>1986. Vol. 50. No. 6 . ' l l 4 l - I I S I

Copyright 1986 by the American Psychological Association. Inc.0022-3 S14/86,'JOO.1'!

Group Polarization: A Critical Review and Meta-Analysis

Daniel J. IsenbergHarvard Graduate School of Business Administration

This article critically reviews recent (1974-1982) group polarization studies that address themselvesto either one of the two primary explanatory mechanisms thought to underly group polarization,namely social comparison and persuasive argumentation processes. A summary of the effect sizes of21 published articles (33 independent effects) suggests that social comparison and persuasive argu-mentation occur in combination to produce polarization, although the persuasive argumentationeffects tend to be larger. Attempts are made to reconcile the two positions, and some suggestions forfurther research are offered.

In 1961 James Stoner observed that group decisions are riskierthan the previous private decisions of the group's members(Stoner, 1961). Since that time several hundred studies haveshown that (a) the ''risky shift" is a particularly pervasive phe-nomenon: (b) on certain decisions groups are more cautious thantheir members: and that (c) both risky and cautious shifts arespecial cases of a more general phenomenon—group-inducedattitude polarization (Moscovici & Zavalloni. 1969; Myers &Lamm, 1976). Group polarization is said to occur when an initialtendency of individual group members toward a given directionis enhanced following group discussion. For example, a groupof moderately profeminist women will be more strongly profem-inist following group discussion (Myers. 1975). Thus, on decisionsin which group members have, on the average, a moderate pro-clivity in a given direction, group discussion results in a moreextreme average proclivity in the same direction.

The group polarization literature is an encouraging exampleof how theoretically and practically meaningful phenomena insocial psychology can be defined and explored through empiricalresearch:

1. In recent years polarization research has been cumulativesuch that subsequent research studies have addressed the prob-lems and issues identified by previous researchers. This has beenamply demonstrated by several excellent literature reviews(Lamm & Myers, 1978; Myers, 1982; Myers & Lamm. 1976).

2. Researchers have pursued lines of programmatic researchrather than one-shot experimental studies (e.g., Blascovich &associates: Myers & associates: Vinokur & Burnstein; Baron &associates).

3. Theoretical explanations of polarization phenomena havebeen disconfirmed (see Pruitt, 1971a. 1971b), thus focusing re-search on an increasingly small number of explanatory mecha-nisms. For example, in 1971 Pruitt identified 11 (overlapping)explanatory mechanisms for choice shifts, whereas by 1978 thislist had been pruned and consolidated into 2 major ones, social

The author would like to thank Robert F. Bales. Roger Brown. DavidMyers, Reid Hastie, and anonymous reviewers for their help and sugges-tions at various stages of this research.

Correspondence concerning this article should be addressed to DanielJ. Isenberg, Harvard Graduate School of Business Administration, SoldiersField Road. Boston, Massachusetts 02163.

comparison processes (Sanders & Baron. 1977), and persuasiveargumentation (Burnstein & Vinokur, 1977).

4. Finally, the polarization literature has made a substantialcontribution to social psychological theory. As one example,Brown (1974) and Myers (1982) both have noted that the grouppolarization literature is significant for its emphasis on a counter-conformity effect because groups shift away from the averageattitude in the group rather than toward it.

Another review of the polarization literature would be redun-dant as several excellent reviews of the literature up to 1978already exist (see Lamm & Myers, 1978; Myers, 1982; Myers &Lamm. 1975. 1976; see also Clark, 1971: Pruitt. 1971a, 1971b).The primary purpose of the present article is to critically review-in particular the recent literature (especially 1974-1982) thataddresses itself to the dialogue between proponents of socialcomparison and persuasive arguments as explanations of attitudepolarization (Burnstein & Vinokur, 1977; Sanders & Baron,1977). The mid-1970s serve as an appropriate point of departurebecause it was at this time that the debate concerning these twoexplanatory processes became highly salient. Furthermore, it wasthen that many researchers who had helped produce the hundredsof risky-shift studies began to veer away from further researchin the field. At the time it appeared that the risky-shift was aninteresting but limited and severely qualified phenomenon thathad already outlived its theoretical usefulness (e.g., Cartwright,1973; Kleinhans & Taylor, 1976). In very recent years enthusiasmfor group polarization research has again begun to wane: it ishoped that an in-depth review will help reorient research in thefield, in particular toward a third wave of research that will in-tegrate group polarization with other social psychological andcognitive phenomena. This article will conclude by suggestingfour areas of integration. In addition to reviewing this recentliterature, attention will be paid to reporting the relative effectmagnitudes of demonstrations of persuasive argument and socialcomparison mediating mechanisms.

Social Comparison

Introduction

As far back as Brown's (1965) seminal discussion of the riskyshift, one of the major explanations of choice shifts has been a

1141

1142 DANIEL J. ISENBERG

social comparison explanation. According to this perspective,people are constantly motivated both to perceive and to presentthemselves in a socially desirable light. In order to do this, anindividual must be continually processing information about howother people present themselves, and adjusting his or her ownself-presentation accordingly. Some versions of social comparisontheory state that many of us desire to be perceived as more fa-vorable than what we perceive to be the average tendency. Oncewe determine how most other people present themselves, wepresent ourselves in a somewhat more favorable light. When allmembers of an interacting group engage in the same comparingprocess, the result is an average shift in a direction of greaterperceived social value.

There are two variations of the above sequence, one empha-sizing the removal of pluralistic ignorance, and the other em-phasizing one-upmanship (bandwagon effects). According to thepluralistic ignorance explanation (see Levinger & Schneider,1969; Pruitt. 197la; Schroeder. 1973: see also Isenberg, 1980),individuals present their own positions as compromises betweentwo tendencies, the desire to be close to one's own ideal, and thedesire not to be too deviant from the impression of the centraltendency of the group. Prior to group discussion, group membersinitially underestimate the group norm and. judging from theinitial ratings of their own positions, are somewhat distant fromtheir ideal. During group discussion, individuals are exposedmore nearly to the true group norm, and thus a discrepancybetween how much better an individual is and would like to bebecomes apparent. Upon making a second set of choices, theindividual group members shift closer to their ideal positions.When this process takes place with most group members, anoverall polarization is observed.

The assumption underlying the pluralistic ignorance expla-nation of choice shifts is that pluralistic ignorance exists becauseof a lack of accurate communication about the "true" beliefs ofthe majority of group members, although it is also likely thatpluralistic ignorance may be due to cognitive biases, such asself-other differentials in person perception (see Jones & Nisbett.1972).

Other investigators have hypothesized a second explanationfor the effects of social comparison processes on polarization(e.g., Brown. 1974: Myers. 1978; Myers. Bruggink, Kersting, &Schlosser, 1980; Myers, Wojcicki, & Aardema. 1977). These andother investigators hypothesize that people are motivated by adesire to be different and distinct from other people in a valueddirection (Fromkin, 1970). In addition, people are also motivatedto present themselves somewhat more favorably than other peo-ple. In other words, w-e want to be different from as well as betterthan other people. Brown states, "To be virtuous . . . is to bedifferent from the mean—in the right direction and to the rightdegree" (1974, p. 469). When making initial ratings along a di-mension, individuals give themselves a rating that is somewhatmore favorable than the rating they presume the average groupmember will give. When individuals directly or indirectly inferwhat the true norm is, they then "improve" their own ratings,thus producing the overall choice shift. Whereas the mechanismproducing choice shifts in the pluralistic ignorance explanationis a compromise between self-enhancement and conformity, themechanism underlying bandwagon effects is a compromise be-

tween self-enhancement and humility. In reality, however, it maybe very difficult to distinguish these two mechanisms empirically.

There are several overlapping variations on the pluralistic ig-norance and bandwagon effects, such as cultural values (Hong.1978), release mechanisms (Pruitt, 197la, 197Ib), self-presen-tation processes (Jellison & Arkin. 1977), specific values (Stoner,1968), and self-anchoring (implicit in Festinger, 1954; Brown,1974).'

The Evidence

The major source of support for social comparison theory hascome from demonstrations that simple knowledge about othergroup members' positions by itself can produce polarization ef-fects. These effects are called "mere-exposure" effects, and wewill use that terminology here. A number of studies have at-tempted to establish that mere exposure to central tendency in-formation can be a sufficient cause of choice shifts (Baron &Roper. 1976: Blascovich & Ginsburg, 1974:Blascovich, Ginsburg.& Howe, 1975, 1976; Blascovich. Ginsburg, & Veach, 1975:Goethals&Zanna, 1979; Myers, 1978; Myers etal., 1980; Myersetal.. 1977: see also Pruitt's reviews, 1971a, 1971b). I shall revieweach study in some depth.

Blascovich and associates. Blascovich and his associatesshould be noted for their persistence in pursuing mere-exposureeffects, as well as for the fact that they use true risk-taking sit-uations in their research. In one study (Blascovich, Ginsburg, &Veach, 1975), three experimental conditions were formed forblackjack playing. One was an individual condition, one was agroup-without-discussion condition, and the third was a group-with-discussion condition. Subjects were randomly assigned toexperimental conditions and played 20 hands of blackjack alonein order to establish a baseline. Then each subject played 20hands of blackjack in the experimental condition. In the group-without-discussion condition, subjects heard each others' betsbut did not discuss them. In the group-with-discussion condition,subjects placed one collective bet after trying to reach a consensus.

There were two relevant findings from the Blascovich, Gins-burg. and Veach (1975) study. First, the individual (no-group)

1 A word about the latter is in order because it has been implied bythe literature but never explicitly stated. Festinger (1954) argued that onereason people seek out comparison information is in order to definesocial reality. For example, what it takes to be considered "intelligent"or "conservative" depends on an individual's comparison with how muchof these qualities the average individual possesses. If the average IQ is 75.then an IQ of 90 is intelligent. If the majority of the people in a givenpopulation are against racial integration, then an individual favoring bus-ing is considered very liberal, even if he or she is against interracial mar-riage. In other words, these qualities are socially defined. This aspect ofsocial comparison theory is usually overlooked in explaining polarization.It is possible that the motivation underlying differentiation of the selffrom the presumed group norm is to maintain one's self-definition, notnecessarily to enhance it. As Brown (1974) comments, "Giving advicein private, then, each participant means to be somewhat audacious. Buthow can he know how to be so since the situations are novel and invented?"Thus, information about the central tendency defines what response isvirtuous, nonvirtuous, risky, or cautious. Social reality and the social selfare defined only through information about other people.

GROUP POLARIZATION 1143

control did not increase the size of their bets between the firstand second blocks of 20 hands, whereas both group conditionsdid show marked increases. r(14) = .44 and .37 for the with-and without-discussion conditions, respectively.2 Second, neithergroup condition showed a greater polarization than the othersfrom block one to block two. This finding was extended by Blas-covich et al. (1976). r(\2) = .44.

Blascovich. Ginsburg. and Veach (1975) and Blascovich et al.(1976) interpreted their studies as showing that norms of risk orcaution emerge, driving either risk or caution upward only whenthe norm is observable by the individual. In agreement withJellison and Arkin (1977), these authors suggested that groupmembers associate ability and skill with riskiness (or caution)and thus become more risky (or more cautious) in order to appearmore able and skillful (see also Blascovich & Ginsburg. 1974;Blascovich, Ginsburg, & Howe, 1975). Nevertheless, one potentialweak spot in their argument is that in order to claim ability-attribution mediators they would have to explain why both shiftsto risk and shifts to caution are found, and why either can beinterpreted as ability under different circumstances.

Baron and Roper. Experiments by Baron and Roper (1976)add support to the mere-exposure hypothesis and specificallyattempt to show how the direction of social value predicts thedirection of polarization. In Experiment 1, subjects participatedin an autokinetic study in which they were assigned to one ofthree conditions, depending on whether they were told that per-ceiving smaller, larger, or better estimates of light movement waspositively related to intelligence. Subjects in the three experi-mental conditions made their light estimates alone, for a 15-trialbaseline, and then for an additional block of 15 trials as a groupin which members simply called their estimates out loud so thatother group members could hear. In a control condition, subjectswere told that larger estimates were related to intelligence, butthey made the second block of 15 estimates as individuals, withoutbeing exposed to others' estimates. The results of this first studywere mixed. In the larger intelligence condition, subjects' esti-mates did polarize in the predicted direction (toward larger es-timates), r(44) = .41, but they did not polarize in the other con-ditions. It appeared that there was an overall tendency for esti-mates to increase over blocks, but the authors did not report ablock main effect. These findings were replicated and extendedin subsequent experiments (Baron & Roper, 1976): /"(39) = .43.

These studies are particularly interesting because the task thatsubjects performed was an argument-poor one, in other words,one in which it was difficult for subjects to generate novel andvalid arguments either in favor of or against perceiving light mo-tion (see Vinokur & Burnstein. 1978b). It appears that this is atleast one example of a situation that one would find difficult toexplain without assuming some purely value-determined com-parison process (Sanders & Baron, I977).3

Myers and associates. Another study (unpublished, reportedin Myers, 1982) demonstrated that exposure to others' positionson argument-poor tasks can produce polarization. Dyads wereshown slides of faces that had been judged previously as eitherattractive or unattractive. On each trial, one member of the dyadmade a judgment of the attractiveness of the slides and announcedthe judgment out loud so that the other dyad member couldhear. Then the second member of the dyad made his or her judg-

ment. The prediction from the mere-exposure hypothesis wasthat for the attractive face, the second member's judgment shouldbe more attractive than the first member's, and the reverse shouldbe true for the unattractive face. In fact, there was a 1.75 to 1tendency for the second member to polarize his or her judgments.As Myers argued, it is rather difficult to imagine that novel orvalid arguments could be generated by the second member inorder to rationalize the shift to a more extreme judgment.

A recent series of studies by Myers and his associates haveprovided additional evidence for the mere-exposure hypothesis(Myers, 1978; Myers et al., 1980: Myers et al., 1977). In the firstof these studies (Myers et al.. 1977) the authors contrasted plu-ralistic ignorance (Levinger & Schneider. 1969) and release theory(Pruitt. 1971a. 197 Ib) explanations of polarization by exposingsubjects to the group average response or to extreme responseswithin the group. The awareness of group norms is assumed tobe the mediating mechanism in pluralistic ignorance (Levinger& Schneider, 1969). Awareness of extremes, which presumablyreleases group members from the constraints of the perceivedgroup norms, is the mediating mechanism in release theory(Pruitt. 197 la, 197 Ib). An attitude survey of 269 members of achurch was conducted in two stages. In stage 1. 100 membersrated their own agreement/disagreement with 16 church-relatedstatements (e.g.. "Ministers should feel free to take a stand fromthe pulpit on some political issue."). Three weeks later the re-maining members (169) either (a) responded to the statementsin a control condition: (b) were given the average of the previous100 members' responses and then responded to the 16 statements;or (c) were given a frequency distribution of the previous 100members' responses and then responded to the 16 statements.Those subjects in the average-exposure and frequency-exposurecondition showed significantly more extreme attitudes comparedto the controls, ij = .23. r(265) = .17." The frequency-exposurecondition showed more extreme attitudes than the pretest baselineas well. There were no differences between subjects in the average

- Throughout this article I recomputed the / and F statistics to themore universal measure of effect size, r, which is the Pearson product-moment correlation and therefore can be identically summed, averaged,and tested for significance. The formula for computing r from Ms r = t/(l2 •*• df)1'2. For F(\. df), r = F/(F + <#') '2 since t2 = F for degrees offreedom = 1. of/'(see Rosenthal. 1978). In several studies investigatorsinappropriately tested specific hspotheses with the omnibus F using greaterthan I dim the numerator. In each of these studies it was possible to testa specific hypothesis with I d f i n the numerator, thus allowing a morepowerful test and allowing the computation of r. In all cases, an r greaterthan 0 indicates an effect in the predicted direction. Further details ofthese calculations are available from the author.

3 Nevertheless, it behooves the authors to explain within their frameworkwhy the smaller intelligence condition in Experiment 1 did not producethe predicted shift.

4 This is only an estimate of r because the exact cell means are notgiven in M\ers et al. (1977). but were estimated from the histogrampresented in the article. Furthermore, the r reflects the effect size of thedifference between the two exposure conditions and the two control con-ditions. Basically, it is the effect size of the F ratio for the comparisonbetween exposure and nonexposure. The SS (between) was calculatedfrom the estimated means, and given the F ratio from the article the SS(error) was calculated.


and frequency-exposure conditions, thus giving an explanatoryadvantage to neither release nor pluralistic ignorance theories.

The first of two studies by Myers (1978) replicated and ex-tended the above findings by using eight Choice DilemmasQuestionnaire (CDQ)5 items, four risky and four cautious, andthe eight traffic cases from Kaplan's (1977) study, four innocentand four guilty shifting cases. Exposure caused polarizationfor both the CDQ items. r(\02) = .27, and the traffic cases.r(!02)= .44.

It is commendable that these studies pit theoretical predictionsagainst one another. Nevertheless, it should be pointed out thatthe above comparisons between release and pluralistic ignoranceexplanations have two potential flaws. First, the manipulation isconfounded with the amount of information: Subjects in therelease conditions were exposed to a full frequency distribution,whereas subjects in the pluralistic ignorance condition were ex-posed to one number, an average. A second criticism is that dif-ferences between scores from release and pluralistic ignoranceconditions may be attenuated by the low salience of the infor-mation (see Borgida & Nisbett, 1977). Whereas Myers foundpolarization effects for both conditions when subjects in both ofthose conditions were exposed to relatively abstract and unvividinformation, exposure to more salient information about thenorm or extremes (for example, via video tape) may actuallylead to greater polarization for one or the other of the two con-ditions. The findings of Isenberg and Ennis (1981) can be inter-preted as showing that deviant group members (i.e.. extremes)are in fact particularly salient in the minds of other group mem-bers.6

In a second experiment. Myers (1978) controlled for the effectsof repeated measurements and had successive groups of subjectsrate the same eight CDQ items after having been exposed to theactual ratings of the previous group. As predicted, polarizationwas greatest for the total of 60 subjects in the exposure conditions.r(\ 16) = .33. Subsequent studies by Myers et al. (1980) havereplicated and extended their demonstration of mere-exposureeffects. r(18) = .86" and r(21) = .43.

Goet/ials and Zanna. Goethals and Zanna (1979) reportedone relatively recent attempt to demonstrate that normative pro-cesses alone can produce polarization. Following reconceptual-izations of Festinger's (1954) statement on social comparisontheory (e.g.. Goethals & Darley. 1977; Jellison & Arkin. 1977:Jellison & Riskind. 1970). Goethals and Zanna argued that themere-exposure hypothesis will onl\ be true when group membersbelieve that they are similar to one another on attributes thatare related to the judgments being made. Since risk taking andability are perceived as related, group members who perceivethemselves as similar in ability should polarize to greater riskfollowing group discussion. "Social comparison theory impliesthat people will feel it is appropriate to take as much risk asothers of equal ability but less risk than those who possess greaterability" (p. 1470). A total of 137 subjects responded individuallyto four CDQ items, rated themselves on overall "talent, creativity,and ability," and then were assigned to one of four conditions.In a group-discussion condition, groups of four subjects discussedthe four CDQ items and then completed the items again in pri-vate. In an information-exchange condition, groups of subjectswere exposed to each other's positions when each group member

held up a card showing his or her position (I will refer to thiscondition as the partial-exchange condition). An information-exchange-of-position-flw/-ability condition (which I will refer toas the full-exchange condition) was like the partial-exchangecondition except that group members also shared their self-ratingsof ability. (As expected, group members were similar in ratingthemselves as above average in ability). In a control condition,subjects simply rerated the CDQ items privately after reconsi-dering them for 10 min. Because the variances across conditionswere heterogeneous, nonparametric statistics were used to com-pare the number of groups polarizing to risk in each condition.Overall, the amount of polarization varied quite substantiallyamong conditions, x2 (3. -V = 32) = 10.42. p < .02, being greatestin the full-exchange condition. More specifically, both the group-discussion and the full-exchange conditions showed greater po-larization to risk than did the partial-exchange condition (p <.05: my own reanalysis of the differences between the partial-and full-exchange conditions showed x2 ( U -V = 16) = 6.35. p <.02. r( 14) = .63. After the experiment, group members rated theaverage group comember in terms of his or her overall talent,creativity, and ability, and it was found that indeed subjects inthe full-exchange condition saw other group members as moresimilar than did subjects in the partial-exchange condition.

The authors interpreted these findings in support of the me-diating role of perceived similarity of abilities in producing po-larization, although this interpretation raises two issues. First,what is the relation between risk taking and risk advocacy? Therisk-ability link assumes that Person A will be a good comparisonfor risk taking for Person B if Person B perceives their risk-relatedabilities as similar. This was not the comparison performed bygroup members in the full-exchange condition, because risk tak-ing was not an issue, only the advocacy of risk (cf. Blascovich &Ginsburg. 1978). Second, a different interpretation might suggestanother mediating mechanism, namely that exposure to others'self-ratings enhanced source credibility: "I had better listen toall of these (self-proclaimed) talented people who are advocatingmore risk than I had expected them to."

Informational InfluencesIntroduction

Much research has been devoted to studying how the proc-essing of relevant information can affect group polarization (e.g..

5 The original risky-shift research bv Stoner (1961) used scenarios inwhich subjects read each scenario and then recommended how muchrisk thev thought the character in the scenario should take. Decisionscenarios involved chess moves, career shifts, professional choices, andso forth.

6 A third qualification of the Myers studies is the possibilitv that releasetheory and pluralistic ignorance theory are in fact different, but the effectis so small as to be tr ivial . Both of Myers's studies showed frequencv-exposure conditions to be slightlv more effective than average-exposureconditions in producing polarization, but the effects, simply and com-bined, were nonsignificant.

" This is based on the comparison of the polarization in the threeexperimental conditions versus the controls. The omnibus f\'3. 18) =3.73. and given the 4 cell means 55 (between) was calculated and thecontrast performed.


Anderson & Graesser, 1976; Bishop & Myers. 1974: Ebbesen &Bowers, 1974: Kaplan, 1977: Kaplan & Miller. 1977: Madsen.1978: Vinokur & Burnstein, 1978a). The most sophisticated andwell-researched version of the information processing explanationfor choice shifts is persuasive arguments theory (PAT; e.g.. Burn-stein & Vinokur. 1975. 1977; Burnstein, Vinokur, & Trope, 1973:Madsen. 1978; Vinokur & Burnstein. 1974. 1978a). PAT holdsthat an individual's choice or position on an issue is a functionof the number and persuasiveness of pro and con arguments thatthat person recalls from memory when formulating his or herown position. Thus, in judging the guilt or innocence of a trialdefendant, jurors come to predeliberation decisions on the basisof the relative number and persuasiveness of proguilt and proin-nocence arguments. Group discussion will cause an individualto shift in a given direction to the extent that the discussionexposes that individual to persuasive arguments favoring thatdirection.

Since the notion of persuasiveness is so central to PAT, someresearch has been devoted to ascertaining the characteristics ofarguments that make them persuasive. Burnstein (1982; Vinokur& Burnstein. 1978b) persuasively argued that two factors deter-mine how persuasive a given argument will be. One factor is theperceived validity of the argument. How true is the argument?Does the argument fit into the person's previous views? Doesthe argument logically follow from accepted facts or assumptions?The second factor determining persuasiveness is the perceivednovelty of the argument. Does the argument represent a new wayof organizing information? Does the argument suggest new ideas?Does the argument increase the perceiver's access to additionalinformation that is stored in memory? For example, the argu-ment. "Cigarette smoking is bad because it causes cancer in thesmoker." is valid, but it is not novel anymore. The argument."Cigarette smoking is bad because it causes cancer in nonsmokerswho inhale the smoke when smokers are present." is relativelynovel. To the extent that the two arguments are perceived asequally valid, the latter, more novel argument should be morepersuasive. Together, the perceived validity and perceived noveltyof an argument determine how influential that particular argu-ment will be in causing a choice shift. The novelty-persuasivenesshypothesis has received experimental support (Vinokur & Burn-stein. 1978b).

PAT seriously qualifies the risky shift phenomenon by makingshifts contingent upon the argument pool within the group. Agiven group may or may not shift in a given direction, dependingupon the possession and expression of persuasive argumentsduring the group discussion. The role of novelty is particularlycentral. If arguments are presented that the individual groupmember is already aware of, a shift in his or her position willnot occur as a result of the discussion (Kaplan. 1977). If novelpersuasive arguments are presented that are opposite to the di-rection initially favored by the group member, their position willshift in the opposite direction and depolarize (Kaplan. 1977:Vinokur & Burnstein. 1978a). Thus, a juror who initially favorsa guiltv verdict will come to favor a more guilty verdict if andonly if he or she is exposed to novel persuasive arguments infavor of guilt.

The specificity of the process by which PAT produces choiceshifts lends it two major strengths as a theory: (a) given appro-

priate information. PAT can predict the direction and extent ofchoice shifts, be they polarizing or depolarizing (Vinokur &Burnstein, 1978a). (b) PAT facilitates the conceptual integrationof individual and group decision making, since the underlyingmechanism is the same for arguments processed privately or ininteraction with other people.

The Evidence

The evidence for the proposition that persuasive argumentsalone can produce choice shifts and attitude polarization is quitestrong and from the start has been one of the best-supportedexplanations of polarization phenomena (see Pruitt. 197la.1971 b). However, the statement that only a persuasive argumentmechanism mediates choice shifts (e.g.. Burnstein & Vinokur.1977) is premature on empirical and theoretical grounds (seeSanders & Baron, 1977, and Burnstein & Vinokur, 1977. for adebate on this particular issue). I will summarize the major find-ings in support of PAT. emphasizing the most recent additionsto the literature not covered in the reviews by Lamm and Myers(1978) and Myers and Lamm (1976). The evidence will be or-ganized around three hypotheses:

1. There is a correlation between the extent of polarizationand the prior preponderance of pro and con arguments that areavailable to group members (the correlational hypothesis).

2. Group polarization can be caused by manipulating thepreponderance of pro and con arguments that are processed (thecausal hypothesis).

3. PAT is a necessary and sufficient cause of group polarizationwhereas social comparison is neither necessary nor sufficient (theexclusivity hypothesis).

Tlie correlational hypothesis. Several studies have shown thatthere is a good correlation between the preponderance of proand con arguments possessed by group members and the sizeand direction of the postdiscussion polarization. For example,Madsen (1978) in Experiment 1, had subjects in one conditiongenerate arguments pro and con on public sex education eitherin their own home state or in a geographically distant state. Theythen rated the persuasiveness of the arguments. In the secondcondition, eight groups of subjects completed pre- and postdis-cussion ratings of their own support of sex education in theirown home state, while eight groups of subjects performed thesame task for sex education in a distant state. An index of averagepersuasiveness (Vinokur & Burnstein. 1974) derived from ar-guments for and against public sex education was highly predic-tive of the actual shifts towards greater or lesser support of publicsex education. /"(13) = .51. across 16 groups of subjects with onecovariate.

In Experiment 2, Madsen used the same paradigm but changedthe issue to be three CDQ-like scenarios involving drug usage.These three scenarios were crossed with a between-subjects ma-nipulation of issue importance. Again, one large group totaling50 subjects generated and ranked the persuasiveness of pro andcon arguments, and 12 small groups totaling about 50 subjectscompleted pre- and postdiscussion ratings of their support ofthe courses of action proposed in the scenarios. Again, there wasa high correlation between the average persuasiveness index for


each scenario and the direction and magnitude of the observedchoice shifts. r(4) = .82 and .64. by two alternative methods.8

These studies and one by Ebbesen and Bowers (1974, Exper-iment 1). r(9) = .65. suggest a high correlation between the pre-ponderance of pro versus con arguments and choice shifts (seealso Bishop & Myers. 1974: Vinokur& Burnstein, 1974. Exper-iment I ) . Nevertheless, as Madsen points out. there are examplesof imperfect predictions from PAT. such as in his second exper-iment where two shift directions were incorrectly anticipated.He suggests that this may be due to the actual dynamics of how-persuasive arguments possessed by individual members may ormay not work their way into the actual group discussion. Ratherthan surveying all of the relevant arguments, groups tend to berather selective in their pursuance of limited lines of argumen-tation. Similarly, it has been observed in a number of studiesthat group members censor the arguments they put forth duringdiscussion in order to support the emerging group consensus (cf.Ebbesen & Bowers, 1974. Experiment 2: Myers & Lamm. 1976.pp. 619-620).

The causal hypothesis. Clearly, the establishment of a strongcorrelation between persuasive argument processing and grouppolarization is impressive, but it does not demonstrate a causallink. Accordingly, a number of studies have gone one step furtherand directly manipulated the preponderance of pro and con ar-guments in order to bring about corresponding shifts (e.g.. Burn-stein & Vinokur, 1973, 1975; Burnstein et al., 1973: Ebbesen &Bowers, 1974, Experiments 2 and 3: Kaplan. 1977: Kaplan &Miller. 1977: Vinokur & Burnstein. 1978b).

Ebbesen and Bowers (1974) in Experiment 3 had subjects listento 10 risky and cautious arguments, while systematically varyingthe proportion of risky to cautious arguments from . I to .9. Theyfound that the correlation between this proportion and polar-ization to risk was .98 across five different proportions (.1. .3..5, .7. and .9). In other words, the higher the proportion, thegreater the polarization to risk. When the proportion fell below.5, the group polarized to caution.

More recently, Kaplan and Miller (1977) showed that subjectstended to recall persuasive arguments that they had been exposedto most recently rather than the ones they had been exposed tofirst. They then composed 24 six-person groups, half of whichwere in a redundant condition, and half of which were in a novelcondition. Each subject in the redundant condition received sixarguments, and the arguments were in the exact same order foreach subject. Each subject in the novel condition received thesame six arguments, but in a given group every subject receivedthe six arguments in a different order. If subjects showed a recencyeffect and recalled the most recent argument, subjects in theredundant condition should recall the same argument, whereassubjects in the novel condition should recall different arguments.To the extent that recalled arguments were discussed more inthe groups, subjects in the novel condition should be exposed tomore novel arguments and thus should shift more. As predicted,the novel arguments groups showed a greater polarization effect.r(!40) = .67, although groups in both conditions polarized sig-nificantly. r( 140) = .76.

Further studies have shown that group polarization is a func-tion of an information pool within a group, where the pool con-sists of partially shared persuasive arguments (Kaplan. 1977, Ex-periment 3: Kaplan & Miller, 1977; Madsen. 1978: Vinokur &

Burnstein, 1974, I978a, 1978b). The greater the number of per-suasive arguments that are novel or nonredundant in a group,the greater the impact of those arguments on group members.Thus, the partially shared (novel) arguments will have the mostimpact.

In their second study, Vinokur and Burnstein (1978b) exploredwhether novel and valid arguments were in fact any more effectivein causing shifts in predicted directions than non-novel argu-ments. In one condition, subjects received novel arguments thatwere prorisk mixed with non-novel arguments that were pro-caution. In the second condition, the same subjects received novelprecaution and non-novel prorisk arguments. The predictionfrom the novelty-persuasiveness hypothesis would be that shiftswould occur in the direction of the novel arguments. In fact, thiswas clearly the case, independent of whether the item was a typ-ically risk- or caution-shifting item. In addition, risky items didshift to risk more than did cautious items, but the effect wasweaker than the predicted effect. r ( 5 l ) = .93 versus .74. Theeffect of novelty was particularly strong for the neutral item,which shifted significantly in the direction of the novel argumentsdepending on whether they were prorisk or precaution.

The exclusivity hypothesis. A number of studies have at-tempted to show that PAT is necessary and sufficient to producepolarization effects and that only PAT can account for these ef-fects. The most recent of these will be reviewed here (Burnstein& Vinokur. 1975; Laughlin & Earley. 1982; Vinokur & Burnstein.1978a: see also Burnstein & Vinokur, 1973: Burnstein et al.,1973). One study (Burnstein & Vinokur, 1975) was designed toshow that exposure to others' positions (mere-exposure) causespeople to privately generate persuasive arguments, which in turnproduces polarization. These authors attempted to demonstratethat exposure to others' positions causes polarization only whenit stimulates the generation of persuasive arguments. In a within-subjects design. 12 groups of 5 subjects responded to three riskyCDQ items in three conditions (after having completed one CDQitem as practice). In the major experimental condition, subjectsresponded to one of the three items, were exposed to each other'sresponses, privately generated arguments for and against risk forthat item, and then responded again to the same CDQ item. Anexposure control condition was identical to the experimentalcondition except that subjects privately generated arguments forand against risk for a different item (the practice item). Thus,subjects in this condition were prevented both from thinkingabout others' responses and from generating relevant arguments.A no-exposure control condition had subjects respond to a CDQitem, privately generate arguments, and respond to the sameCDQ item again. Thus, the first condition purportedly showsthe effects of exposure on argument generation, which is hy-pothesized to mediate the effects of exposure on polarization.

The authors found a risky shift in the experimental condition,r( 11) = .89, a nonsignificant cautious shift in the exposure con-trol, r = .43,' and no shift in the no-exposure control, r = .03.The experimental condition polarized to risk significantly more

8 The second correlation is a more conservative post hoc analysis thatI conducted on Madsen's data.

9 We are not told which item was used as a practice item, but it isconceivable that subjects generated precaution arguments that then gen-eralized to the focal item, thus attenuating the usual polarization to risk.


than the other two conditions, r(22) = .68. In comparing thebalance of actual prorisk and procaution arguments generatedby subjects in the experimental and no-exposure conditions, itwas found that the weight and number of prorisk arguments wasgreater in the experimental conditions, whereas this was not truefor the procaution arguments. Although the difference betweenprorisk and procaution arguments was significant for the exper-imental condition but not for the no-exposure condition, thedifference between these conditions was apparently not significantas should have been predicted by the model.

This is an admirable study in its use of content analysis, inthe strength of the findings, and in its specific predictions thatwere tested by planned comparisons.'0 Nevertheless, there aresome aspects of the study that are vulnerable to criticism. Themajor criticism is that Burnstein and Vinokur (1975) first dis-torted the SCT position somewhat and then attacked the distor-tion. For example, in the exposure control condition the exper-imenter prevented subjects from thinking after they had beenexposed to others' positions by immediately giving them a taskto generate arguments for a different item. In a very real sensethis was a distraction task. The implicit assumption is that socialcomparison processes require no thought. However, this is notthe case; information processing in SCT must occur at two junc-tures, the first being in processing the fact that others are differentfrom what one had expected, and the second being in the cognitivecalculus of how to be different from the average "in the rightdirection and to the right degree." Burnstein and Vinokur (1975)also assumed the role of strong emotion in social comparisonprocesses, stating that group members are supposed to be "dis-tressed" (p. 414). "disturbed," or "surprised" (p. 417) by dis-covering that they are not as different from others as they hadpreviously thought. To my knowledge, nowhere is such emotionsuggested by advocates of social comparison theory."

In one of the most thorough and innovative studies of grouppolarization, Vinokur and Burnstein (1978a) argued that in mostcases, PAT and SCT make similar predictions about the directionof polarization, except for the case when two subgroups withdivergent positions (one pro-J and the other pro-K) try to reacha decision. In this situation, SCT holds that each member of thepro-K. subgroup will compare himself to the members of his ownsubgroup and then become more pro-K after discussion, whereasmembers of the pro-J subgroup will become more pro-J. Theresult will be polarization between subgroups. PAT argues thatwithin each subgroup most of the arguments favoring a givenalternative will have been shared already and thus there will berelatively few novel (and thus persuasive) valid arguments withinsubgroups. Across subgroups, however, new arguments will beheard, thus facilitating a shift toward the other subgroup, anddepolarization will be observed.

In the first of two experiments, subjects first completed sevenCDQ items: four risky, two cautious, and one neutral. On thebasis of their responses, experimenters composed several groupsof six members for each item (in other words, groups were formedfor one item, then re-formed for the next item, and so on). Thecriterion for forming each group was that there were twosubgroups of 3 subjects, and for the particular item to be discussedthe average responses for the two subgroups differed by approx-imately 5 scale points (out of 10). For half of the groups, a saliencemanipulation had the three subgroup members sit together op-

posite the other subgroup with the labels ("Risky Subgroup" and"Cautious Subgroup") in front of them. For the other groups,members simply sat together. In both conditions group membersdiscussed each CDQ item with the instructions to attempt toreach consensus. After responding to all of the items in sevendifferent subgroupings. subjects made their postdiscussion ratingson all seven items. The measure of attitude polarization waspostdiscussion minus prediscussion ratings. The measure of de-polarization was the difference between the means of each of thetwo subgroups of 3 subjects each.1'

The findings of Experiment 1 were clear: both polarization ofthe total groups of 6 and depolarization between the twosubgroups of 3 occurred, the latter being two to three times aslarge as the former. These effects apparently were equivalent forgroups in the salient and nonsalient subgroup conditions (effectsizes are not given, nor do we know if the effects were in thepredicted direction). Groups polarized to risk on risky items andto caution on cautious items, but overall the two subgroupsshowed a strong tendency to converge toward one another. r( 17) =.87.l3 Analyses of the subgroups showed that on the risky itemsthe cautious subgroups shifted more toward risk than did therisky subgroups shift toward caution. Likewise, on the cautiousitems the risky subgroups shifted more toward caution than didthe cautious subgroups shift toward risk. On the neutral itemboth subgroups tended to shift (depolarize) toward each other.

Experiment 2 replicated and extended these findings but in-stead of the CDQ items, subjects responded to two value items(e.g., "Do you think capital punishment is not justified underany circumstances or is justified for special cases of murder?"),two personal taste items (e.g., "Is football or basketball moreinteresting to watch?"), and three factual items (e.g., "When willthe LInited States become independent of foreign sources of en-ergy?"). Otherwise, the procedures were identical to those usedin Experiment 1. Again, there were apparently no effects ofsubgroup salience (again, no effect directions or sizes were re-ported), both polarization (on six of the seven items) and de-polarization occurred, and depolarization was stronger (on sixof the seven items). In both cases, the exception was the capitalpunishment item. With two exceptions both subgroups shiftedtoward each other, accounting for the large depolarization effect,r(2Q) = .84 (see Footnote 13: again, the capital punishment itemwas one of the two exceptions). Finally, combining the findingsfrom both experiments, depolarization was greatest for factual

10 One wonders wh> a 2 x 2 analysis of variance was not used to testthe predicted interaction of condition with balance of prorisk/procautionarguments.

" There is a confound in the comparison between the experimentaland the no-exposure control conditions, namely that subjects always re-sponded to the no-exposure control condition first when participating inthe experiment. Then the remaining two conditions were counterbalanced.It is conceivable that subjects needed to warm up to the experimentalsituation, and this caused them to generate arguments of different kindsin the first trial (i.e.. the no-exposure control condition).

i: An additional group of subjects completed the two CDQ items andseven items used in Experiment 2 in order to control for regression tothe mean.

13 This effect size is based upon the average of seven is for the depo-larization score on each item, as well as on the harmonic mean. A slightlydifferent number of groups was used for each of the seven items.


items (3.92), second for the CDQ items (2.44), third for taste(1.90), and fourth for value (1.01).

These two experiments are quite interesting primarily becausethey are surprisingly the first to study polarization betweensubgroups. This remains a serious shortcoming in the group po-larization literature. The authors interpret their results as showingthat PAT makes an accurate prediction (depolarization) whereasSCT makes an inaccurate one (polarization between subgroups).A more cautious interpretation would be that here is yet anotherdemonstration of postdiscussion convergence (see Myers. 1982)occurring along with an average shift, where the members mostextreme in the direction of polarization shift less compared tothose most extreme in the opposite direction (see Ferguson &Vidmar. 1971). Whether or not these two experiments actuallytest SCT depends upon how much we believe that the saliencemanipulation in fact caused group members to compare them-selves to the other 2 members of their own subgroup. I thinkthis can be reasonably questioned given (a) the instructions to"reach consensus." (b) the fact that all subjects were students atthe same university, and (c) that the students may have adheredto norms of conflict avoidance. Given the choice between beingless extreme and avoiding conflict, versus comparing themselvesto their own subgroup and becoming more extreme, I think thatmost students would choose the former, independent of any per-suasive arguments.

It is to the credit of PAT that its specificity allows anomaliesto be informative, and the anomaly of the capital punishmentitem is instructive because it is the only item showing both sig-nificant polarization and no depolarization. Data presented inthe article indicate that the polarization was against capital pun-ishment, due primarily to nonliberal subjects becoming moreliberal. According to PAT, this could occur only if (a) the liberalsubgroup did not hear any new arguments for capital punishment,and (b) the nonliberal subgroup did hear novel arguments againstcapital punishment. There is no evidence that this was the case:in fact, the authors themselves argue that for value items, novelarguments are essentially exhausted. A simpler alternative ex-planation to the data on the capital punishment item is thatdiscussion engaged a liberal norm in a liberal setting, and thatattitudes polarized accordingly, a typical finding in polarizationresearch (Myers, 1975: Myers & Bach, 1974).

The Vinokur and Burnstein (1978a) studies do pose a criticalquestion for group research in general, namely, under what cir-cumstances should polarization between groups occur? Wouldit be possible for polarization between groups to occur if bothgroups (for example, Palestinians and Israelis) was exposed tothe same arguments and the argument pool is exhausted? Ev-eryday experiences in families, labor relations, and internationalpolitics suggest that such argument-poor polarization can occur(Sherif, 1966). PAT itself suggests a way to understand how thismight happen, namely that the arguments generated and proc-essed are novel but they are rejected as invalid (Vinokur & Burn-stein, 1978b). However, this puts us back in the arena of nor-mative mechanisms because the perception of validity is by def-inition value based. This point is reinforced by the finding thatnovelty leads to persuasiveness only when perceived validity ishigh (Vinokur & Burnstein, 1978b). Given the ubiquity of in-tergroup phenomena (e.g., Sherif, 1966) we would expect thatwhen an outgroup is perceived as "bad," their arguments will be

perceived as invalid, and thus novel arguments (and rational dis-cussion) will be unpersuasive. Without siding with either SCTor PAT. it seems that the perception of validity is one importantconceptual link between the two.

A final exclusivity study by Laughlin and Earley (1982) re-portedly found stronger support for PAT than for SCT based onthe observation that, across CDQ items, repeated trials, and con-ditions (individual vs. group), decisions taking the perspective ofa hypothetical stranger were riskier than those taking the per-spective of a friend or oneself. Why is this counter to SCT?Laughlin and Earley argued that the hypothesized desire to bebetter than the average in SCT should manifest itself primarilywhen making decisions from one's own perspective and not whenmaking decisions from the stranger perspective. Thus when riskis valued, one should rate oneself as riskier than the stranger,and when caution is valued one should rate oneself as morecautious.

Curiously, Laughlin and Earley used the perspective main effectto test this hypothesis rather than the item by perspective inter-action. Whereas they concluded that SCT has a problem becauseacross items the self perspective is more cautious than the strangerperspective, there is nothing in SCT that would predict a per-spective main effect at all. The more appropriate item perspectiveby interaction yields an F less than 1, F(\, 564) = .07. Thismight still be considered a problem for SCT. but certainly arelatively minor one.14

Summary and Conclusions

Table 1 summarizes the effects from the more recent studiesshowing effects either of mere-exposure or of persuasive argu-ments. The average effect sizes from each type of study are sub-stantial, but the effect of persuasive argumentation is particularlystrong (.746 average r vs. .436)." In many of the studies reportedhere, both social comparison and persuasive argumentation areoccurring simultaneously, but there are studies that show effectsof social comparison in argument-poor tasks (e.g.. Baron & Roper,1976: see also Myers, 1982: Vidmar, 1974). There are also studiesthat show effects of argumentation in comparison-poor tasks (e.g..

14 One source of potential support for the exclusivity hvpothesis hasbeen the relative lack of effects of mere-exposure to other group members"positions compared to exposure to persuasive arguments. For example.Kaplan (1977. Experiment 2) found that when confronted with two con-tradictory sources of influence, proincrimination persuasive argumentsand proexoneration ratings of group members, the persuasive argumentsinfluenced subjects' subsequent ratings, whereas mere-exposure did not.Care should be taken, however, in interpreting this finding as evidencefor the exclusivitv hypothesis. An alternative interpretation would be thata written list of proincrimination arguments would be more vivid andsalient (Borgida and Nisbett. 1977) than a set of numbers representingmembers' proexoneration positions.

15 Some care must be exercised in interpreting this difference in averageeffect size. Data reported in several of the PAT studies (e.g.. Vinokur &Burnstein. 1974) allow the calculation of the correlation between predictedand observed scores across CDQ or similar items. Given the lack of anappropriate within subjects error term, it is not possible to calculate anr that is directly comparable with the other«. Thus, several of the reportedrs probably are higher than they would be based on an appropriate errorterm with <# based on number of subjects, not number of items.


Burnstein et al., 1973; Ebbesen & Bowers, 1974), that is, tasksthat do not permit the inference of group comembers' positions.In the cases of the argument-poor studies the effect sizes are verysimilar to the average effect size for mere-exposure studies. Like-wise, for comparison-poor studies, the effect sizes are similar tothe average effect size for persuasive arguments studies. At thispoint in time there is very good evidence that there are twoconceptually independent processes even though outside of thelaboratory they almost always co-occur.

The analysis of effect sizes is important for both the planning

Table 1Effect Sizes for Recent Group Polarization Studies onMere-Exposure and Persuasive Argumentation

Stud>

Mere-exposure studies"

Baron & Roper (1976)Experiment 1Experiment 2

Bell &Jamieson( 1970)Bell & Jamiesonf 1970)Blascovich. Ginsburg. & Veach ( 1975)Blascovich, Ginsburg. & Howe (1975)Blascovich. Ginsburg. & Howe (1976)Blascovich & Ginsburg (1974)Blascovich & Ginsburg (1974)Clark &Willems( 1969)Clark &Willems( 1969)Goethals& Zanna(l979)Myers (1978)

Experiment 1Experiment 1Experiment 2

Myers, Bach, & Schreiber (1974)Myers. Bruggink, Kersting, & Schlosser (1980)

Experiment 1Experiment 2

Myers, \\ojcicki. & Aardema ( 1977)Teger& Pruit t( l967)Wallach& Kogan(1965)Wallach& Kogan(1965)'a.t

r

.41

.43

.12

.21

.37

.74

.39

.29

.57

.52

.36

.63

.27

.44

.33

.52

.86

.43

.17

.51-.03

.37

.436

df

44392323147

172727242414

102a

102116

18

1827

26518I I11

Persuasive arguments studies

Burnstein & Vinokur (1975)Burnstein. Vinokur, & Trope (1973)Ebbesen & Bowers (1974)


Kaplan (1977)Experiment IExperiment 2

Kaplan & Miller (1977)Madsen(l978)


Vinokur & Burnstein (1974)Experiment IExperiment 2Experiment 3

.68

.39

.65

.98

.44

.53

.67

.51

.57

.86

.93

.84

.746

22252

93

8888

140

134

333

" These two correlations are not independent, thus the average of thesetwo correlations (.408) was used in computing the average r for all of themere-exposure studies.

of future experiments as well as the interpretation of past ones.For example, Burnstein & Vinokur (1977) cited the lack of mere-exposure effects in several studies, but reanalyses suggest effectsizes that are respectable (.3-.4) but insignificant perhaps as aresult of the small number of subjects in the experiment. Forexample. Clark and Willems (1969) found that information ex-change of positions led to no shift in one of their conditions.t(24) = 1.87, whereas the associated r(.36) is very similar tothose in Table I . Thus, the conclusion that this is a failure toreplicate is not necessarily founded in this study (a Type 2 errormay have been committed).

On a related point, many investigators have made it difficultto perform meta-analyses and at the same time impeded tests ofspecific hypotheses by using omnibus F-tests (with df(num)greater than 1). These make the translation to r difficult and testonly the general (and conceptually meaningless) hypothesis thatthere is some significant amount of variance associated with theindependent variables. Given the maturity of the field and ac-cumulated knowledge of the effects of various stimuli, very spe-cific a priori hypotheses can and should be stated using plannedcontrasts. A discussion of this technique is beyond the scope ofthis article (see Winer, 1971), but any number of degrees of free-dom in the numerator other than 1 should be a warning flag forresearchers (Rosenthal & Rosnow, 1984).

Integrative Questions

Given the support for both PAT and SCT as mediating pro-cesses, it behooves investigators to develop theories that accountfor the interaction between SCT and PAT and that address thefactors that moderate the emergence of one or the other form ofinfluence. The following are four questions that suggest how tointegrate PAT and SCT into a more conceptually coherent po-sition, a position that also serves to integrate group polarizationwith other social psychological phenomena.

Under what conditions will group processes be more affectedby either rational argumentation or social comparison? Onepotential moderating variable is decision characteristics. To theextent that a decision has many factual or logical componentswe would expect rationality to be more prominent than socialdesirability. The items that Vinokur and Burnstein (1978a)showed to depolarize the most in group discussion (i.e., be lesssusceptible to social comparison processes) were those involvingmatters of fact.

A different potential moderating variable is ego involvement.In a decision where group members are highly ego-involved sev-eral parameters change: (a) values are engaged; (b) attention isconstricted to a narrow range of information input and issues;and (c) argument pools tend to be exhausted because ego-in-volving issues have already been heavily processed by individualsprior to discussion. We would expect capital punishment, fem-inism, pacifism, and drug usage to be ego-involving comparedto the CDQ scenarios and questions of whether basketball orfootball is the more interesting spectator sport. Thus social com-parison should operate more strongly in the former situations,and persuasive argumentation should operate more strongly inthe latter.

H 'hat are the causal paths among social desirability, persuasiveargumentation, and attitude polarization? Myers and Lamm


(1976) suggested that social desirability can influence argumen-tation through action commitment, but that persuasive argu-ments do not affect social desirability (Myers & Lamm. 1976,Figure 1). The distinction between rationality and rationalizationis germane here and needs to be paid attention to in particularby the persuasive arguments theorists. The former implies ar-gumentation in the absence of social desirability, whereas thelatter suggests that social desirability can motivate persuasiveargumentation. Action commitment helps, but it is not necessaryfor the internal generation of arguments to reduce dissonancewith socially desirable positions.

In overt group interaction, normative processes can do morethan motivate group members to think of supporting arguments;they can also cause members to skew their spoken arguments tofavor one alternative over another. As Myers and Lamm (1976)argued, self-censoring probably occurs in group decision making.If so, we might hypothesize that the greater the pluralistic ig-norance in a group prior to discussion, the greater the amountof self-censoring that will be observed as members attempt toconform to the misperceived norm. As in release theory, whenthe true norms are discovered, self-censoring will still occur, butin the opposite direction as members strive to be better than theaverage.

Hmv is information about group members' positions combinedinto a mental concept of the "group norm"? What are the pro-cesses by which group members attend to, encode, and storeinformation about these descriptive and prescriptive normswithin their group? This issue reverses the causal sequence inthe second question above (normative —• cognitive) and suggeststhat informational processes can influence normative ones. Thus,certain characteristics of information such as vividness (Taylor& Fiske, 1978) can influence how group members perceive theirgroup's norms. For example, it is possible that information aboutextreme or deviant group members is cognitive!}1 overavailableand will have an inordinate influence in determining perceptionsof norms. An obvious area of research is the relation betweensocial cognition and group polarization. Burnstein (1982) hasalready begun to establish links between polarization and infor-mation processing.

Hmv can group polarization phenomena be related to attitudechange processes in general (e.g.. Sherif& Holland, 1961) andattitude polarization in particular? One distinction typicallymade in the attitude change literature is between source andmessage characteristics (McGuire, 1969). The debate betweenPAT and SCT can be recast in these terms. For example, socialcomparison theorists indirectly focus on who or what is the sourceof the norms that form the basis for social comparison. If thesource is a reference group of similar others, then a perceiveddiscrepancy between own and others' positions should generategroup polarization. Persuasive argument theorists seem to dis-regard the source and differentiate among message characteristics,such as novelty and validity. When seen in this light, one reasonthe two positions do not see eye to eye is that they are dealingwith different aspects of a more generalized process of attitudechange.

Quite unwittingly. James Stoner opened up an important sub-field of research in small group behavior that has resulted inseveral robust conclusions. It is hoped this research will continuein such a way that it becomes integrated with other important

theoretical streams in social psychology as well as with the prac-tical requirements of functioning in real-life groups.

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