Influence of Message Credibility and the Pressure to Hide Tobacco Consumption in the Effectiveness...

In¯uence of Message Credibility and the Pressure to Hide

Tobacco Consumption in the Effectiveness of the `Bogus

Pipeline’ Technique

TOMAÂ S JESUÂ S CARRASCO GIMEÂ NEZ1* & MARIÂA LUNA ADAME2

1Universidad de Granada, Spain; 2Centro de PsicologõÂa Altair, Granada, Spain

ABSTRACT Aims: The objective of our research was to study the in¯uence of the messagecredibility (according to its mode of transmission) and the pressure to hide consumption(the use of anonymous or named questionnaires) regarding the effectiveness of the `BogusPipeline’, a frequently used resource to increase the honesty of self-reports of tobaccoconsumption among adolescents. Design: Random assignment of 18 classes (previouslydivided into two groups) to six experimental conditions (six groups per condition): `BogusPipeline’ with video presentation and anonymous questionnaire; `Bogus Pipeline’ withvideo presentation and named questionnaire; `Bogus Pipeline’ with oral presentation andanonymous questionnaire; `Bogus Pipeline’ with oral presentation and named question-naire; `without Bogus’ and with anonymous questionnaire; and `without Bogus’ and withnamed questionnaire. Setting and participants: Students (n ˆ 504) from three middleschools in Granada, Spain. Measurement: Self-reported smoking consumption. Find-ings: The presentation of the message through a video is more effective than theexclusively oral presentation. The `Bogus Pipeline’ technique is effective when there ispressure to hide tobacco consumption. Conclusion: The `Bogus Pipeline’ technique isparticularly effective in conjunction with a video presentation and when there is pressureto hide smoking.

Introduction

Smoking prevention research needs accurate measures of smoking behaviour.Among children and adolescents, the fear of being recriminated against byparents or teachers, their interest in appearing more mature and their reluctanceto collaborate with adults make the credibility of self-reports on smoking doubt-ful. To solve this problem, Evans et al. (1977) proposed the use of a techniqueknown as `Bogus Pipeline’ originally developed by Jones & Sigall (1971) in theevaluation of interpersonal attraction. The basis of this technique is as follows:if subjects are convinced that the evaluator has a machine or method forphysiologically measuring that infallibly proves real behaviour, then the honestyof their self-reports increases.

Drugs: education, prevention and policy ISSN 0968±7637 print/ISSN 1465±3370 online # 2002 Taylor & Francis Ltdhttp://www.tandf.co.uk/journalsDOI: 10.1080/0968763011009 5591

Drugs: education, prevention and policy, Vol. 9, No. 2, 2002

* Correspondence to: TomaÂ s JesuÂ s Carrasco GimeÂ nez, Departamento de Personalidad, EvaluacioÂ n yTratamiento PsicoloÂ gico, Faculty de PsicologõÂa, Universidad de Granada, 18071 Granada, Spain.

Tel: 34-58-24 42 75. Fax: 34-58-24 37 49. E-mail: [email protected]

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In the case of tobacco consumption, such efforts to convince have been tried bycommunicating to the subjects that their self-reports would be corroboratedthrough a laboratory test, in most cases to determine thiocyanate levels in salivaor the concentration of carbon monoxide in exhaled air. Nevertheless, the studiesdone on the effectiveness of the technique show contradictory results (Akers et al.,1983; Bauman & Dent, 1982; Bauman et al., 1982; Botvin et al., 1984; Bray et al.,1979; Campanelli et al., 1987; Cohen et al., 1988; Gillies et al., 1982; Hansen, 1983;Hansen et al., 1985; Lauer et al., 1982; Luepker et al., 1981; Murray & Perry, 1987;Murray et al., 1987; Werch et al., 1987, 1989). It has been proposed that the reasonfor this absence of unanimity in the literature is that the `Bogus Pipeline’technique is effective only when the conditions satisfy the logic demands of thetechnique, namely that the message transmitted by the evaluator be convincing(i.e. that the subjects have no doubt that the researcher has an infallible means ofproving the veracity of their self-reports) and the existence of pressure to hidetobacco consumption (Carrasco et al., 1993).

As regards the ®rst point, the transmission of a convincing message, four typesof procedures have been used: oral, comics, video and live presentations. In theoral transmission of the message the subjects are verbally told that their self-reports will be con®rmed by analysing saliva or air samples. In the presentationwith comics, explanations are supported by graphic illustrations; in the videopresentation a projection demonstrating the processing of the sample analysis isshown; and in the live presentation the sample analysis is performed before thesubjects.

It can be surmised that the more realistic the transmission of the message, thegreater the effect of the `Bogus’ technique, and that as a result, we can put theprocedures of the presentation in order from least to greatest effectiveness asfollows: verbal, comic, video and live demonstration. Werch et al. (1989) com-pared oral and comics procedures. The oral was the most effective. Murray et al.(1987) included a condition in which a live presentation was carried out andanother in which the demonstration was followed by a video. No signi®cantdifferences were found in either of them. In Botvin et al. (1984) the videopresentation was the most effective, followed by the comics and then the verbal,although the differences were minimal, not statistically signi®cant. The results ofthe meta-analysis done by Aguinis et al. (1993) support the superiority both of thelive presentation and the video presentation on the remaining procedures.

As regards the second point, the pressure to hide tobacco consumption seemsto be determined, fundamentally, by the level of anonymity of the questionnairesand the guarantees of con®dentiality offered to subjects. It has been proposedthat the `Bogus’ technique would be effective only if the subjects were asked towrite their names on the questionnaires or if these included questions that help toidentify them (date of birth, sex, year and so on), and/or if guarantees ofbelievable con®dentiality are not given. Only two studies (Akers et al., 1983;Murray & Perry, 1987) have compared the effectiveness of anonymity versus the`Bogus’ technique at the time of increasing self-reported consumption. Akers et al.(1983) found that the addition of the `Bogus’ technique to a procedure of`randomized response’ did not increase the percentage of self-reported tobaccoconsumption. Murray & Perry (1987) found that the effectiveness of anonymityand the `Bogus’ at the time of increasing self-reports about tobacco consumptionwas very similar, which suggests that the `Bogus’ is unnecessary in such con-

188 T. J. Carrasco GimeÂnez & M. L. Adame

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ditions. However, the fact of having transmitted the `Bogus’ message verbally(both articles mentioned doing it this way) questions these conclusions.

The main objective of the present study was to verify the role of these twofactors, credibility message and pressure to hide consumption, in the effectivenessof the `Bogus Pipeline’ technique.

Method

Subjects

The sample was made up of 504 students distributed in 18 classes from threemiddle schools in Granada, Spain. None of the schools had ever participated in asimilar study. With 33 of the subjects, no relative data were obtained for any ofthe studied variables , which left the sample with 471 subjects. The sample was51.4% female and the students’ mean age was 15.9 years, SD ˆ 1:44. Theparticipants were 92.5% of the students enrolled in the schools included in thestudy. Students participated voluntarily in the study during their regular classes.Co-operation was total (100% of the students present in classes when the studywas carried out agreed to participate).

Design and Procedure

These 18 classes were randomly divided into two groups, with 36 groupsresulting. These groups were assigned to one of the following six experimentalconditions (six groups per condition): `Bogus Pipeline’ with video presentationand anonymous questionnaire (`VI_AN’), `Bogus Pipeline’ with video presenta-tion and named questionnaire (`VI_NA’), `Bogus Pipeline’ with oral presentationand anonymous questionnaire (`VE_AN’), `Bogus Pipeline’ with oral presentationand named questionnaire (`VE_NA’), `without Bogus’ and with anonymousquestionnaire (`WI_AN’), and `without Bogus’ and with named questionnaire(`WI_NA’). To avoid the diffusion of the applied procedure in the `Bogus’conditions one of the two groups from the ®rst evaluated class in each schoolwas randomly assigned to the WI_AN’ condition and the second to the `WI_NA’condition; in the second class the ®rst group was assigned to the `WI_AN’condition and the second to the `WI_NA’ condition; in the third, the ®rst groupwas assigned to the `VE_AN’ condition and the second to the `VE_NA’ condition;in the fourth, the ®rst group to the `VE_AN’ condition and the second to the`VE_NA’ condition; in the ®fth, the ®rst group was assigned to the `VI_AN’condition and the second to the `VI_NA’ condition; and in the sixth class, the ®rstgroup to the `VI_AN’ condition and the second to the `VI_NA’ (Table 1).

The classes were randomly assigned to this sequence. With its purpose being toavoid diffusion, all the classes from each of the schools were evaluated on thesame day. In this way, we consider that we were able to reconcile threefundamental methodological demands for an investigation of such characteristicsbut which have rarely been reached in previous studies: to avoid the identi®ca-tion of the class with experimental condition; to get a random assignation of thegroups to the experimental conditions; and to prevent the diffusion of theexperimental procedure. Teachers were absent when the procedure was carriedout on each class. In all the conditions the con®dentiality of the answers to thequestionnaire was emphasized. The procedure was done by two groups of

Effectiveness of the `Bogus Pipeline’ Technique 189

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graduate students trained for the purpose. Moreover, they were supervised at alltimes by the authors of this research. Both groups intervened in the evaluation ofthe three schools.

We are now going to present a summary of the procedure followed in each ofthe conditions below.

`Bogus Pipeline’ with a video presentation and anonymous questionnaire. The subjectswatched a video entitled: `How to know if a person smokes or not’. The videobegan by presenting a 14-year-old girl. Next, the procedure of collecting the girl’ssaliva sample was shown (in the context of the evaluation of all the class) andafter that, freezing it until analysis. The process of analysing the sample in amodern laboratory then followed (in particular, determining thiocyanate levels)and as a result of it, the distinctive colour of the sample, a bright red/orangecolour, that indicated tobacco consumption. Immediately after that, a sample ofsaliva was taken from the subjects following the procedure described by Pechacek

et al. (1984). Next, the subjects were asked to ®ll in a questionnaire, and told not towrite their names on them. The questionnaire included questions regardingbehaviour related to health (physical exercise, oral hygiene, sleeping habits,tobacco and alcohol consumption) and issues related to risk factors regardingdrug consumption. The questionnaire also solicited the subject’s date of birth andsex, data that allowed the assignation of an identi®cation code.

`Bogus Pipeline’ with a video presentation and questionnaire with name. The sameprocedure described for the previous condition with the exception that subjectswere asked to write their names on the questionnaires.

`Bogus Pipeline’ with oral presentation and anonymous questionnaire. The sameprocedure as the `VI_AN’ condition except that instead of watching a video thesubjects were told verbally that saliva samples would be taken and later analysed,showing them to be smokers or not.

`Bogus Pipeline’ with oral presentation and named questionnaire. As in the previousprocedure except that the subjects were asked to write their names on thequestionnaires.

`Without Bogus’ and with anonymous questionnaire. The subjects answered aquestionnaire without a `Bogus Pipeline’ message being transmitted to them.They were asked not to write their names on the questionnaires.


Table 1. Outline of study design

Bogus: video Bogus: verbalpresentation presentation Without Bogus

Named questionnaire VI_NA VE_NA WI_NA

Anonymous questionnaire VI_AN VE_AN WI_AN

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`Without Bogus’ and with named questionnaire. As in the previous case except thatsubjects were asked to write their names on the questionnaires.

As in most of the previous studies of the `Bogus Pipeline’ the options ofresponse corresponding to the question of tobacco consumption were grouped intwo categories for the statistical analysis.

1. Non-smokers and ex-smokers: subjects who have never smoked or who havetried tobacco (more than 6 months ago) and did not continue smoking orsmoked regularly but stopped smoking more than 6 months ago.

2. Smokers: subjects who have recently tried tobacco (less than 6 months ago),who smoke sporadically (less than once a month), who smoke at least once amonth, who smoke least once a week, or who smoke at least once a day.

Results

Table 2 presents the percentages of subjects who admit to tobacco consumption intheir self-reports. The only statistically signi®cant differences were those existingbetween the `VI_NA’ and `WI_NA’ (À2 ˆ 10:72; df ˆ 1; p < 0:01) and `VI_NA’ and`VE_NA’ (À2 ˆ 7:05; df ˆ 1; p < 0:05) conditions.

This suggests that the `Bogus Pipeline’ technique is effective when it isadministered through a video and under conditions of pressure to hide tobaccoconsumption, and that the `Bogus Verbal’ procedure is not enough to counteractthe pressure to hide consumption derived from the named questionnaire. It canalso be concluded from these results that in the case of absence of pressure to hideconsumption (anonymous questionnaires), the `Bogus Video’ as well as the`Bogus Verbal’ procedures increase the percentage of self-reports in tobaccoconsumption, although not in a statistically signi®cant manner. The greaterpercentages of subjects who admit smoking under `WI_AN’ condition in com-parison with the `WI_NA’ condition suggest that the non-anonymous nature ofthe questionnaires led to a pressure to hide consumption.

Discussion

At the beginning of our paper we pointed out that the objective of this researchwas to study the in¯uence of message credibility (according to its transmissionmode) and the pressure to hide consumption (the use of anonymous or namedquestionnaires) regarding the effectiveness of the `Bogus Pipeline’. According tothe ®rst point, the role of message credibility, the results clearly point toward thesuperiority of the video presentation over oral presentation. In our opinion, thismeans of presentation should become the standard protocol for carrying out the


Table 2. Percentage of subjects who admit smoking on their self-reports `Bogus Pipeline’ conditions

VI_AN VI_NA VE_AN VE_NA WI_AN WI_NA

% 40.7 46.8 35.1 27.8 30.7 21.8

n 59 77 74 108 75 78Missing 2 7 7 8 6 3

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technique. Regarding the second point, the pressure to hide consumption, ourresults con®rm that the technique `Bogus Pipeline’ is especially effective in thepresence of such pressure (as shown by the signi®cant statistical differencebetween conditions `VI_NA’ and `WI_NA’) and that in its absence only leads toa slight increase in the validity of self-reports (10% more subjects admit smokingin condition `VI_AN’ with regard to condition `WI_AN’, although the difference isnot statistically signi®cant).

Therefore, the present results indicate that the `Bogus Pipeline’ technique iseffective when given the condition that the technique’s logic itself demands,namely the existence of pressure to hide tobacco consumption. Consequently, itsapplication is recommended in those situations where the existence of suchpressure is presumed (use of named questionnaires, identi®cation code or toinclude questions that allow the identi®cation of the subject, lack of familiaritywith the evaluators, and so on) and always with a video presentation.

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Influence of Message Credibility and the Pressure to Hide Tobacco Consumption in the Effectiveness...

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