Short Note

Evidence that intentions based onattitudes better predict behaviour thanintentions based on subjective norms

PASCHAL SHEERAN*, PAUL NORMAN andSHEINA ORBELL

University of She�eld, UK

Abstract

Self-determination theory suggests that better prediction of behaviour will be observedfrom intentions based on attitudes than intentions based on subjective norms. Analysesof the intention±behavior relationship for both attitudinally versus normatively con-trolled people and attitudinally versus normatively controlled behaviours supported thishypothesis. Copyright # 1999 John Wiley & Sons, Ltd.

The theory of reasoned action (TRA, Fishbein & Ajzen, 1975) provides an importantframework for predicting and understanding social behaviour. The TRA proposesthat a person's intention to perform a behaviour (e.g. `I intend to do X in the nextweek') is the key predictor of behavioural performance. Behavioural intentions aredetermined by attitudes (people's positive or negative evaluation of their performingthe behaviour, e.g. `Doing X in the next week would be good/bad') and subjectivenorms (people's perceptions of social pressure from signi®cant others to perform thebehaviour, e.g. `Most people who are important to me think that I should do X in thenext week') though the relative weights attached to attitudes versus subjective normsdi�er for di�erent intended behaviours (Fishbein & Ajzen, 1975). Accumulatedevidence indicates that attitudes and subjective norms are good predictors ofintentions and that intentions are reliable predictors of behaviour (e.g. Sheppard,Hartwick & Warshaw), 1988).

Recently, Tra®mow and Finlay (1996) used within-subjects correlations to identifyrespondents whose intentions to perform 30 behaviours were more strongly predictedby attitudes than subjective norms (79% of their sample). When these `attitudinallycontrolled' respondents were examined separately, the signi®cant e�ects of subjective

CCC 0046±2772/99/020403±04$17.50 Received 1 September 1997Copyright # 1999 John Wiley & Sons, Ltd. Accepted 9 June 1998

European Journal of Social PsychologyEur. J. Soc. Psychol. 29, 403±406 (1999)

*Correspondence to: Dr Paschal Sheeran, Department of Psychology, University of She�eld, She�eldS10 2TN, UK. e-mail: p.sheeran@she�eld.ac.uk

norms obtained in previous between-subjects analyses were eliminated while thee�ects for attitudes were enhanced. Conversely, when normatively controlled partici-pants were examined, the e�ects of subjective norms were enhanced. These ®ndingsdemonstrate that people as well as behaviours determine whether intentions areattitudinally versus normatively controlled. However, an important question remains,namely, do intentions based on attitudes better predict behaviour than intentionsbased on subjective norms? The present study addresses this question.

There are grounds for hypothesising that intentions based on attitudes will betterpredict behaviour than intentions based on subjective norms. According to self-determination theory (e.g. Ryan, Sheldon, Kasser & Deci, 1996), it is important todistinguish two types of motivationÐautonomous and controlled. Autonomousmotivation involves intentions which are experienced as self-chosen and emanatingfrom one's self. Such behaviours are perceived as having an internal locus of causality.In contrast, controlledmotivation involves plans and behaviours that are initiated andpursued because of pressures external to the self (they have an external locus ofcausality such as approval or punishment from signi®cant others). Evidence from avariety of behaviours, including attendance at alcoholism treatment and weight lossover 23 months, indicates that participants with autonomous motivation are morelikely to achieve their goals than participants with controlled motivation. While theamount or level of motivation (intention) does not necessarily di�er when people areautonomous versus controlled, the type or orientation of motivation does, and thisresults in di�erent probabilities of behavioural performance.

Ryan et al.'s distinction between autonomous versus controlled participants clearlyparallels Tra®mow and Finlay's distinction between attitudinally versus normativelycontrolled participants (cf. Carver, 1996). However, neither Ryan et al. nor Tra®mowand Finlay have addressed the intention±behaviour relationship. We hypothesise thatstronger intention±behaviour relationships obtain for intentions based on attitudescompared to intentions based on subjective norms.

METHOD

The present study employs a subset of measures from a larger research project.One hundred and eighty-seven undergraduates completed standard multi-item directmeasures of attitudes, subjective norms and intentions regarding 30 behaviours(median alphas � 0.82, 0.92, and 0.97, respectively). Behaviours (e.g. exercise, fruitconsumption, class attendance) were assessed by self-report two weeks later. Findingsfor the prediction of intentions and behaviours from TRA variables were very similarto previous research (Sheeran, Tra®mow, Finlay, Norman & Orbell, unpublishedmanuscript).

RESULTS

Attitudinally versus Normatively Controlled People

We adopted two within-subjects strategies to test our hypothesis. First, we computedwithin-subjects correlations between attitudes and intentions, norms and intentions

404 P. Sheeran, P. Norman and S. Orbell

Copyright # 1999 John Wiley & Sons, Ltd. Eur. J. Soc. Psychol. 29, 403±406 (1999)

and intentions and behaviour. Consistent with predictions, the strength of theattitude±intention relationship had a slightly signi®cant, though moderate, positivecorrelation with the intention±behaviour relationship (r � 0.26, p5 0.001) where-as the norm±intention relationship and the intention±behaviour relationship werenot signi®cantly correlated (r � 0.10, ns). Second, we divided the sample who hadstatistically signi®cant within-subjects intention±behaviour correlations (r4 0.30)according to the strength of their within-subjects attitude±intention and subjectivenorm±intention correlations. Participants who had a statistically signi®cant attitude±intention r (r4 0.30) but non-signi®cant subjective norm±intention r were deemed tobe under attitudinal control (N � 24). Normatively controlled participants werethose whose subjective norm±intention r was statistically signi®cant but theirattitude±intention r was not (N � 24). Despite no di�erences between the groups onthe mean or variance of intention scores, a median test showed stronger intention±behaviour correlations among attitudinally compared to normatively controlledparticipants (median rs � 0.60 and 0.50, respectively, Z � 1.97, p5 0.05).

Attitudinally versus Normatively Controlled Behaviours

Between-subjects regressions of intentions on attitudes and subjective normsindicated that attitudes had larger beta coe�cients than subjective norms of 21 outof the 30 behaviours. We computed the mean intention and behaviour scoresfor these attitudinally controlled behaviours and also for the nine normativelycontrolled behaviours. Unfortunately, attitudinally controlled behaviours had higherintention scores than normatively controlled behaviours (Ms � 4.56 and 4.34,respectively, t(186) � 3.74, p5 0.001). This meant that in order to determine whetherbehaviours whose intentions were under attitudinal control were more likely to beperformed than behaviours whose intentions were normatively controlled, we had toconduct an ANCOVA, controlling for intentions, to compare the behaviour of twogroups. Not surprisingly, the covariateÐintentionÐwas associated with behaviour(F (1, 185) � 48.61, p5 0.001). Importantly, however, even after controlling forstrength of intention, attitudinally controlled intentions were more likely to beenacted than normatively controlled intentions (Ms � 9.45 and 4.23, respectively,F (1, 185) � 578.71, p5 0.001).

DISCUSSION

Fishbein and Ajzen (1975) suggested that the relative weights attached to attitudesversus subjective norms in the prediction of intentions will vary for di�erentbehaviours while Tra®mow and Finlay (1996) demonstrated that these weights varyfor di�erent types of people. However, these analyses do not appear to anticipate adi�erential impact of attitudinal versus normative control on the strength of theintention±behaviour relationship. The present study used self-determination theoryto derive the hypothesis that intentions based on attitudes will better predictbehaviour than intentions based on subjective norms. This prediction was con®rmedfor both attitudinally controlled people and behaviours.

Attitudes versus norms 405

Copyright # 1999 John Wiley & Sons, Ltd. Eur. J. Soc. Psychol. 29, 403±406 (1999)

The present study extends previous research by exploring the implications ofself-determination theory for the TRA and by explicitly addressing the intention±behaviour relationship (rather than behavioural performance per se) from a self-determination theory perspective. The analyses reported here show that attitudinallycontrolled or autonomous intentions are associated with improved behaviouralperformance compared to normatively controlled (`controlled') intentions. This islikely because attitudinally controlled intentions are an expression of one's self andare undertaken with a full sense of choice. They are implemented with a sense of truevolition (Ryan et al., 1996). In contrast, normatively controlled intentions are experi-enced as pressured or coerced and consequently have poorer motivational impact,despite equivalent strength.

Our study has several implications for future research. First, it provides insightinto the strength of the intention±behaviour relationships. For example, researchersobtaining poor intention-behaviour consistency might usefully examine the strengthof attitude±intention and subjective norm±intention correlations in discussingtheir ®ndings. Second, since our analyses point to the motivational signi®cance ofattitudinal versus normative control of behavioural intentions, this suggests thatgreater attention should be paid to this issue and especially to factors such as thestrength of the collective self which determine attitudinal versus normative control(cf. Tra®mow & Finlay, 1996).

In sum, the present study demonstrates the importance of distinguishing betweenattitudinal versus normative control in understanding the intention±behaviourrelationship.

REFERENCES

Carver, C. S. (1996). Some ways in which goals di�er and some implications of those di�er-ences. In P. M. Gollwitzer & J. A. Bargh (Eds), The psychology of action (pp. 645±672).London: Guildford Press.

Fishbein, M. & Ajzen, I. (1975). Belief, attitude, intention and behavior; An introduction totheory and research. Reading, MA: Addison-Wesley.

Ryan, R. M., Sheldon, K. M., Kasser, T., & Deci, E. L. (1996). All goals are not createdequal: An organismic perspective on the nature of goals and their regulation. In P. M.Gollwitzer & J. A. Bargh (Eds), The psychology of action (pp. 7±26). London: GuildfordPress.

Sheppard, B. H., Hartwick, J., & Warshaw, P. R. (1988). The theory of reasoned action:A meta-analysis of past research with recommendations for modi®cations and futureresearch. Journal of Consumer Research, 15, 325±343.

Tra®mow, D., & Finlay, K. (1996). The importance of subjective norms for a minority ofpeople. Personality and Social Psychology Bulletin, 22, 820±828.

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Copyright # 1999 John Wiley & Sons, Ltd. Eur. J. Soc. Psychol. 29, 403±406 (1999)