Imagining and Explaining Hypothetical Scenarios: Mediational Effects on the Subjective Likelihood of

Health-Related Outcomes’

PAUL SPARK$ PETER R. HARRIS University of Sussex

Falmer, Brighton, United Kingdom University of Shefjeld

Sheffieeld, United Kingdom

MONIQUE RAATS University of Surrey

Guildford, United Kingdom

Imagining and explaining hypothetical events have been shown to increase the subjective likelihood of those events occurring. At the same time, it has been suggested that reducing unrealistic optimism ahout health risks (i.e., increasing the subjective likelihood of nega- tive health outcomes) might motivate health-protective behavior. In exploring the implica- tions of these issues for health-promotion goals, 2 experiments (Ns = 334 and 328) involving postal questionnaires are reported in which attempts are made through the use of imagine-and-explain scenarios to manipulate the subjective likelihood of a negative out- come (heart disease) and of a positive outcome (reducing fat consumption). The greater success of the manipulation of dietary change expectations than of heart disease expecta- tions suggests the potential benefits of focusing directly on planning goal strategies in relation to health beneficial behaviors.

Optimism, as the story goes, is conducive to health and well-being (Taylor & Brown, 1988). People who hold optimistic illusions contrast with those possibly mildly depressed or low self-esteem people who have more realistic expectations of the future. On the other hand, it has been suggested either that underestimating the risks that one faces or unrealistic optimism might lead people to ignore or to have a reduced motivation to engage in health beneficial precautionary behavior (cf. van der Pligt, 1994; Weinstein, 1989). Some reconciliation of these views is offered by the suggestion that although optimism about the effectiveness of

‘The authors thank Sarah Grugeon, Duncan Hedderley, and Karen Oltersdorf for their contribu- tion to the research reported here and to the anonymous reviewers for their insightful comments on an earlier draft of the manuscript. The research was carried out as part of the project, “The Development of Models for Understanding and Predicting Consumer Food Choice” (AIR2 CT94 1315), funded by the European Union.

2Correspondence concerning this article should be addressed to Paul Sparks, Department of Psy- chology, University of Sussex, Falmer, Brighton BN I 9SN, United Kingdom. E-mail: p.sparks@, sussex.ac.uk

Journal of Applied Social Psychology, 2003, 33, 4, pp. 869-887. Copyright 0 2003 by V. H. Winston & Son, Inc. All rights reserved.

870 SPARKS ET AL.

precautions might strengthen motivation and reduce anxiety in some contexts, “when health problems have not yet appeared and are controllable, a tendency to downplay one’s own risk may interfere with appropriate self-protective action” (Weinstein & Klein, 1995, p. 132).

The unrealistic optimism phenomenon (e.g., Weinstein, 1980, 1983, 1984) indicates, among other things, that people tend to underestimate their compara- tive risk standing concerning health-threatening hazards. This phenomenon has been demonstrated across a wide range of behavioral domains (Weinstein, 1980, 1989) and might be more accurately described as “comparative unrealistic opti- mism” (Klein & Weinstein, 1997, p. 28). The phenomenon is sometimes con- strued as indicating that many people would benefit from information about the actual risks they face so that they might make more accurate personal risk assess- ments (which ultimately might have a positive motivating influence on the per- formance of health beneficial behaviors).

Although there is, to date, little evidence of harmful effects on health-related behaviors of comparative unrealistic optimism (van der Pligt, 1998), attempts to debias people’s risk perceptions (i.e., to reduce comparative unrealistic opti- mism) have been seen as attempts to motivate behaviors conducive to health (e.g., Weinstein & Klein, 1995). Indeed, recent evidence has indicated that infor- mation about comparative risk levels might be a more important motivational influence than is information about absolute risk levels (Klein, 1997). Two cru- cial questions then arise. First, is it possible to manipulate people’s perceptions of absolute or comparative risk? Second, if it is possible to manipulate these percep- tions, does this help motivate behavior change designed to reduce those risks?

In this paper, we address these issues and report some research designed to influence people’s subjective likelihood of carrying out behaviors conducive to health. The behavioral focus of the reported research is fat consumption: High intake levels of dietary fat have been associated with heart disease and cancer risks (Cannon, 1992; World Cancer Research Fund, 1997), and current recom- mendations are that average fat consumption levels (especially levels of saturated fat) should be reduced (World Cancer Research Fund, 1997; World Health Orga- nization, 1990).

Imagination and Explanation Effects

Comparative unrealistic optimism has proved to be remarkably resilient. Suc- cessful attempts at reducing or eliminating it are rare in the published literature (Harris, Middleton, & Joiner, 2000). Particularly rare are approaches that are suc- cessful in increasing people’s perceptions of the risks that they face. However, there is plentiful evidence that after people imagine an event or outcome hap- pening, they tend to be believe that it is more likely to occur (Anderson, 1983; Carroll, 1978; Gregory, Burroughs, & Ainslie, 1985; Koehler, 1991; Levi &

IMAGINING AND EXPLAINING HYPOTHETICAL SCENARIOS 871

Pryor, 1987; Taylor & Pham, 1996; Tversky & Koehler, 1994). This technique might offer a way of increasing subjective or perceived likelihood to the self and, in the process, perhaps of reducing comparative optimism (Armor & Taylor, 1998). This, in turn, might help to motivate behavior change designed to reduce risk.

Anderson (1983), for example, investigated the effect of how imagining one-self in a behavioral scenario influenced intentions and subjective likelihood of carrying out that behavior. Based on behavioral scripts presented by the experimenter, student participants were asked to imagine six behavioral scenarios (e.g., blood donation, taking a new part-time job) and to draw cartoons of the sce- narios with each script presented either once, twice, or three times. For each behavior, participants were asked to draw the main character either carrying out or not carrying out the behavior in question. The main character in the scenarios was the participant, a close friend or a disliked acquaintance. The results showed that imagining behaviors led to greater intentions to carry out a behavior when the self was depicted and when the scenario was imagined on two or three occasions.

Gregory et al. (1985) had students listen to a scenario that described them being involved in an automobile accident. Subsequently, those in the experimen- tal group reported that they would be more likely to be involved in an automobile accident than were control participants (who had imagined an unconnected scenario). In a second study using similar materials, it was found that post- experimental attitudes toward traffic safety laws were more positive among the experimental group than among the control group.

Sherman, Cialdini, Schwartzman, and Reynolds (1985) found that when par- ticipants were asked to imagine experiencing either easy-to-imagine symptoms of a disease (e.g., low energy levels, muscle aches, severe headaches) or d@cult- to-imagine symptoms (e.g., “a vague sense of disorientation,” a malfunctioning nervous system, an inflamed liver), easy-to-imagine symptoms attracted higher subjective likelihood ratings than did difficult-to-imagine symptoms. Control participants were simply told about the symptoms of the disease, but were not asked to imagine experiencing them. There was also a significant interaction, with those in the easy-to-imagine condition giving higher ratings of subjective likelihood than did those in the control group, whereas those in the difficult-to- imagine condition gave lower ratings of subjective likelihood than did those in the control group.

Sherman and Anderson (1 987) suggested that the imagination-explanation procedure “may be useful in a variety of applied settings” (p. 3 10). They found that psychotherapy outpatients who were asked to imagine themselves in four therapy sessions and to list the personal attributes that would mean they would complete four therapy sessions showed lower dropout rates than clients who completed an unconnected imagine-and-explain task (about an “irrelevant event”) and clients who did not take part in the study.

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More recently, Wilson and LaFleur (1995) reported studies in which asking participants to give reasons why they might or might not carry out a series of behaviors raised their subjective likelihood of carrying out those behaviors. However, there were no effects of giving reasons on self-reported behavior mea- sured 6 weeks later. The accuracy of self-predictions was also lower in the exper- imental group than in the control group.

In relation to comparative optimism, Weinstein and Klein (1995) described a series of studies that attempted to “debias” participants with respect to their risk estimates for themselves compared to estimates made about others. Debiasing here refers to reducing comparative unrealistic optimism. In one study (Study 4), they drew upon some of the aforementioned literature suggesting that the genera- tion of reasons for an outcome is likely to lead to greater expectations that the outcome will occur. They asked participants to list the factors that either increased or decreased their chances of developing either a serious weight prob- lem or a drinking problem. For the weight problem only, participants in the risk- decreasing reasons condition gave significantly lower ratings of subjective likeli- hood of actually experiencing this problem than did participants in the other two conditions. However, there was no difference found for either problem between the control condition and the risk-increasing reasons condition. Nevertheless, Armor and Taylor (1998) suggested that imagining a particular (desirable) out- come might be at the heart of the cognitive origins of unrealistic optimism.

Thus, there are plenty of examples of research where imagining and explain- ing hypothetical scenarios has been shown to increase the subjective likelihood of the events depicted in those scenarios actually occurring. Certain factors (e.g., the number of times the scenario is imagined and the difficulty or ease of imagin- ing the scenario) seem to play some role in the manifestation of these effects. Since behavioral impacts also have been demonstrated, there are considerable implications of this research for the promotion of health beneficial behaviors. Moreover, although published evidence for imagination effects on comparative unrealistic optimism is limited, it has been suggested that imagination might be one of the core cognitive processes underlying this phenomenon. Further research into these promising effects for those interested in inducing behavior change appears warranted by these findings and suggestions.

In pursuit of this issue, two experiments seeking to debias people’s percep- tions of diet-related risks or to increase their subjective likelihood of pursuing health beneficial behaviors are reported in this article. The broad aim is to assess methods that eventually might be adopted effectively for use in health-promotion campaigns. A main objective is to assess the basic proposal that imagining and explaining outcomes or behaviors leads to an increased subjective probability that those outcomes or behaviors actually will occur (no attempt was made at this stage to separate imagination and explanation effects, since this has proved diffi- cult in the past and since this was not judged to be crucial to our broad aims). We

IMAGINING AND EXPLAINING HYPOTHETICAL SCENARIOS 873

are interested in people’s subjective probabilities, not only of absolute levels of personal negative outcomes, but also of comparative levels. In order to assess the effects of any change in risk perceptions on motivation to engage in health protec- tive behavior, assessment was made both of the subjective likelihood of a negative health outcome and of intentions to engage in health beneficial behavior change.

Experiment I

In Experiment 1, two different scenarios were incorporated: one relating to experiencing heart disease, and one relating to reducing fat consumption. We were concerned with examining the effects of imagining a future negative event, not only on the subjective likelihood of the occurrence of that event, but also on the subjective likelihood of participants initiating a behavior change. We also decided to investigate whether the subjective likelihood of behavior change might be predicted better by inducing participants to imagine that change directly than by inducing participants to imagine negative outcomes that might motivate and lead to behavior change. We included two additional control groups: a group that received no imagine-and-explain task and a group that was given an irrele- vant imagine-and-explain task (in order to be sure that any observed effects could not be attributed to imagining and explaining, per se).

From these considerations, it is expected that the subjective likelihood of experiencing heart disease will be higher for participants asked to imagine and explain experiencing heart disease than for those asked to imagine and explain reducing fat consumption (and than for the control groups). Conversely, we expect that subjective likelihood of reducing fat consumption will be higher for those participants who are asked to imagine and explain reducing fat consump- tion than for those asked to imagine and explain experiencing heart disease (and than for the control groups).

Method

Participants

Participants were recruited via an advertisement placed in a newspaper in a town in central England. From 457 initial inquiries, 334 participants (249 female, 85 male) completed the study within the required time period. The participants’ mean age was 33.6 years. The modal educational level was to Ordinary (0) or General Certificate of Secondary Education (GCSE) level (usually involving leaving hll-time education at 16 years of age).

Materials

There were three experimental conditions. Participants were asked to read one of the following three paragraphs and to respond by providing a causal account for the hypothetical scenario depicted in that paragraph.

874 SPARKS ET AL.

“Heart disease” condition (n = 84). Imagine that you were to get heart dis- ease at some time during your lifetime because of your current diet. Please spend a few minutes trying to picture this happening: imagine some future time when you actually have heart disease because of what you eat now. After you have thought about this for a few minutes, please write down (in the space below) as much as you can about what it could be about your current diet that might lead you to get heart disease at some time during your lifetime. Important: only write down those things about your current diet that might cause you to get heart dis- ease in the future. If at first you find this difficult to do, please persist: we usually find that people can come up with something after a few minutes of trying.

“Reduce fat” condition (n = 84). Imagine that you were to reduce your fat consumption within the next year because of your current diet. Please spend a few minutes trying to picture this happening: imagine some time within the next year when you are reducing your fat consumption because of what you eat now. After you have thought about this for a few minutes, please write down (in the space below) as much as you can about what it could be about your current diet that might lead you to decide to reduce your fat consumption within the next year. Important: only write down those things about your current diet that might lead you to reduce your fat consumption within the next year. If at first you find this difficult to do, please persist: we usually find that people can come up with something after a few minutes of trying.

“Television ’’ control condition (n = 76). Imagine that you were watching a particular television programme that you think is an “average” programme. Please spend a few minutes trying to picture this happening: imagine you were watching a television programme that you think of as neither particularly good nor particu- larly bad. After you have thought about this for a few minutes, please write down (in the space below) the name of the programme that you were imagining and as much as you can about why you think of this programme as an average pro- gramme. Important: only write down those things about the programme that make you think of it as average. If at first you find this difficult to do, please persist: we usually find that people can come up with something after a few minutes of trying.

Space was provided for participants in each condition to record their replies. No task control group (n = 90). Participants in this condition did not com-

plete any imagine-and-explain task.

Procedure

Once participants had completed this initial task, they answered questions about their subjective likelihood of experiencing heart disease in the future and of reducing their fat consumption in the following year. These questions were also asked with the “average other” as the target. Participants also answered other questions about fat consumption, the details of which are not reported here.

IMAGINING AND EXPLAINING HYPOTHETICAL SCENARIOS 875

Subjective likelihood of experiencing heart disease. Participants were asked “How likely do you think you are [the average person of your gender and age in this country is] to get heart disease at some time in the future because of your [their] current diet?” Responses were recorded on an 1 1 -point scale ranging from 1 (extremely unlikely) to 11 (extremely likely).

Subjective likelihood of reducing fat consumption. Participants were asked “How likely do you think you are [the average person of your gender and age in this country is] to reduce your [their] fat consumption within the next year?” Responses were recorded on an I I -point scale ranging from 1 (extremely unlikely) to 11 (extremely likely).

Participants were randomly allocated to one of the experimental conditions or to one of the control groups. They were sent a postal questionnaire to complete and return (they also subsequently completed two questionnaires unrelated to this research). Each participant was paid E5.00 (about $8) for participation.

Results

As a manipulation check, two independent coders assessed whether partici- pants carried out the experimental task as instructed (participants’ responses were categorized as either answering the question, partially answering the question, or not answering the question). After an initial 79% agreement (Cohen’s k = .73), the coders discussed outstanding items in order to reach agreement about catego- rization (a third independent judge decided the categorization when the two cod- ers could not agree). Only participants who were judged to have completed the task as instructed were included in the analyses. This left 73 participants in the heart-disease condition, 37 in the reduce-fat condition, and 75 in the television control condition.

Subjective Likelihood of Experiencing Heart Disease

A 2 x 4 (Target: Self vs. Average Other x Condition: Heart Disease vs. Reduce Fat vs. Television Control vs. No Task Control) ANOVA for mixed designs on the subjective likelihood of heart disease ratings showed a significant main effect for target, F( I , 270) = 201.7 1, p < .0001, and a significant target by condition interaction, F(1, 370) = 2 . 6 4 , ~ = .05. Overall, participants rated their own likelihood ( M = 5.71) as lower than that of the average other ( M = 7.90). In order to examine the interaction effect, we computed two one-way unrelated ANOVAs. The first, on the subjective likelihood of oneself experiencing heart disease showed a significant effect, F(3, 270) = 2.68, p < .05. Planned compari- sons (Holm’s multistage Bonferroni t ) showed that participants in the heart- disease condition gave ratings of greater likelihood ( M = 6.08) than did partici- pants in the television control condition ( M = 5.05), t(270) = 2 . 5 3 , ~ < .05, but not

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Table 1

Subjective Likelihood of Heart Disease and Reducing Fat Consumption: Experiment 1

Imagine and explain

Heart disease Reduce fat Television No task (n = 73) ( n = 37) (n = 74) (n = 90)

M SD M SD M SD M SD

Heart disease Participantsa 6.08 2.70 6.14 2.35 5.05 2.38 5.77 2.39

Average othera 7.80 1.45 8.08 1.42 7.84 1.54 7.97 1.67

Difference -1.71 2.63 -1.95 2.33 -2.78 2.31 -2.20 2.24 Reducing fat consumption

Participantsa 7.41 2.39 7.68 2.30 7.27 2.53 7.37 2.70

Averageothera 6.36 2.26 6.70 2.03 6.34 2.23 6.14 2.29

Difference 1.05 2.63 0.97 2.79 0.93 2.75 1.22 2.71

aRated on an 1 1-point scale ranging from 1 (extremely unlikely) to 11 (extremely likely).

than participants in the reduce-fat condition ( M = 6.14) or the no task control condition ( M = 5.77). The second one-way unrelated ANOVA, on ratings of the average other’s likelihood of heart disease, showed no difference between condi- tions, F(3,273) = 0.38, ns (Table 1).

A comparative subjective likelihood score was computed by subtracting par- ticipants’ ratings for the average other from their ratings for themselves. A one- way ANOVA then revealed a significant effect, F(3,270) = 2 . 6 4 , ~ < .05. Planned comparisons showed that participants in the heart-disease condition ( M = - 1.7 1) gave higher comparative subjective likelihood scores (indicating less comparative unrealistic optimism) than did participants in the television control condition ( M = -2.78), t(270) = 2 . 7 3 , ~ < .05. Scores for the reduce-fat ( M = -1.95) and no task control groups ( M = -2.20) were intermediate between these two (Table 1).

Subjective Likelihood of Reducing Fat Consumption

A 2 x 4 (Target: Self vs. Average Other x Condition: Heart Disease vs. Reduce Fat vs. Television Control vs. No Task Control) ANOVA for mixed designs on the subjective likelihood of reducing fat consumption showed a significant main effect for target, F( 1,270) = 36.34, p < .0001, but neither a main

IMAGINING AND EXPLAINING HYPOTHETICAL SCENARIOS 877

effect for condition nor a target by condition interaction. Participants rated their own likelihood of reducing fat consumption ( M = 7.39) as higher than that of the average other ( M = 6.33).

Discussion

Contrary to the suggestion in previous research that imagining and explaining an outcome leads to a heightened perception of likelihood for that outcome, we found only limited evidence for an effect of condition on subjective likelihood of experiencing heart disease. Relative to the no-task control, the means for the heart-disease condition were in the predicted direction, but the differences were too small to be significant. The same was true for the judgments of comparative likelihood. The findings for subjective likelihood of reducing fat consumption showed no effects of condition. For both dependent measures, however, there was an effect of target showing that, overall, participants were comparatively unrealistically optimistic about their chances of experiencing heart disease and their likelihood of reducing fat consumption.

Ratings of subjective likelihood of experiencing heart disease did, however, interact with target. Here, self-ratings of subjective likelihood were higher (and, as a consequence, comparative unrealistic optimism was lower) in the heart-dis- ease condition than in the television control condition. Inspection of the means relative to those in the no-task control suggests that this effect arose from a com- bination of a slight elevation of the risk judgments in the heart-disease condition and a lowering of these judgments among those in the television control condi- tion. A number of possibilities suggest themselves for this effect. One that is con- sistent with the existing literature on risk perception is that those in the television condition (who were imagining a recreational activity) experienced more positive affect than did those in the heart-disease condition (who were imagining an unde- sirable outcome) and that these differences in affect mediated the differences in risk perception (e.g., Salovey & Birnbaum, 1989).3 Alternatively, the effects might be cognitive. For example, imagining being at home watching television might reduce one’s feelings of vulnerability to untoward events (e.g., a diagnosis of a life-threatening disease) by making more accessible images relating to the normality, security, and predictability of one’s everyday life. At the very least, this effect points to the importance of using control groups that enable the effects of imagining and explaining per se to be separated out from the effects of the content of what is being imagined. Before speculating further on this particular effect, however, it must be replicated.

Given the strength of the claims in the literature about the effects of imagina- tion on likelihood judgments and the possible role of imagination in unrealistic

3We are grateful to the anonymous reviewer who suggested this possibility.

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optimism, it was desirable to conduct a further test. Therefore, we ran a second experiment. In the process, we took the opportunity to refine both the imagina- tion task required of our experimental participants and the risk and behavior judgments that we asked them to make.

Experiment 2

It is apparent that there was some feature of the reduce-fat instructions in Experiment 1 that was unclear. The marked number of participants who did not complete the task as instructed suggests this. (Indeed, the reduction in statistical power resulting from the loss of these participants might have contributed to the absence of significant effects of this manipulation.) Moreover, although they were instructed to imagine that they were reducing their fat consumption, partici- pants in this condition were asked also to list those features of their current diet that might cause them to undertake such a reduction. Thus, they were asked to carry out two separate (though related) tasks, and this might have contributed to their difficulties.

In order to improve the conceptual clarity of the reduce-fat condition and the compliance of the participants, therefore, those in this condition in Experiment 2 were asked to focus on the ways in which they would bring about change if they were to reduce their fat consumption. That is, participants were asked to focus on what elsewhere might be termed their (conditional) implemental intentions (Gollwitzer, 1996) or their (conditional) strategic images (Beach, 1990). This change has the added benefit of making the difference between the two imagina- tion conditions equivalent to one between imagining the outcome (heart disease) and imagining the process by which one might avoid this outcome (reduce fat). This distinction has been proposed as making a significant difference in the suc- cess of imagination tasks (Pham & Taylor, 1999; Taylor & Pham, 1996; see also Oettingen, 1996).

In addition, we took the opportunity to include additional questions in order to tease out important distinctions between participants’ subjective likelihood of experiencing heart disease both if they were to make dietary changes and if they were not to make dietary changes. It has been argued (Ronis, 1990; van der Velde, Hooykas, & van der Pligt, 1996) that participants’ conditional risk esti- mates are both easier to interpret than are unconditional risk estimates and are more beneficial in the prediction of intentions and behavior. The inclusion of conditional risk estimates in our study enabled an assessment of the effects of the experimental manipulation on participants’ subjective likelihood of heart disease, independent of the effects on any behavior change that might be perceived as reducing risk. Questions about the perceived likelihood of both trying to reduce fat consumption and of actually succeeding in reducing fat consumption were also asked, in order to tease apart effects on perceived motivation and on the

IMAGINING AND EXPLAINING HYPOTHETICAL SCENARIOS 879

perceived likelihood of achieving the goal of reduced fat consumption (given the motivation to attempt this).

Method

Participants

Participants were recruited via a newspaper advertisement to complete a postal questionnaire; 328 participants (263 female, 65 male) completed the study within the required time period. The modal age category was 4 1-50 years, and the modal educational level was to 0 or GCSE level.

Materials

“Heart disease” condition (n = 87). Imagine that you were to get heart dis- ease at some time during your lifetime because of your current diet. Please spend a few minutes trying to picture this happening: Imagine some future time when you actually have heart disease because of what you eat now. What could it be about your current diet that might lead to heart disease? After you have thought about this for a few minutes, please write down (in the space below) as much as you can about what is bad about your current diet (in terms of heart disease risks). Important: Only write down those things about your current diet that you consider bad (in terms of heart disease risks). Make sure you do this before you complete the rest of the questionnaire.

“Reduce fat” condition (n = 89). Imagine that you were to reduce your fat consumption within the next year. Please spend a few minutes trying to picture some time within the next year when you are reducing your fat consumption: Imagine the changes you would make to your eating habits in order to do this. How exactly would you go about reducing your fat consumption? After you have thought about this for a few minutes, please write down (in the space below) as much as you can about how you would go about reducing your fat consumption within the next year. Important Only write down the ways in which you would go about reducing your fat consumption within the next year. Make sure you do this before you complete the rest of the questionnaire.

“Television control” condition (n = 78). Imagine that you were watching a particular television program that you think is an “average” program. Please spend a few minutes trying to picture this happening: Imagine you were watching a television program that you think of as neither particularly good nor particu- larly bad. After you have thought about this for a few minutes, please write down (in the space below) the name of the program you were imagining and as much as you can about why you think of this program as an average program. Important: Only write down those things about the program that make you think of it as average. Make sure you do this before you complete the rest of the questionnaire.

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No-task control condition (n = 74). In a no-task control condition, partici- pants did not take part in any task.

All participants then received the following questions (participants also answered other questions about fat consumption, details of which are not reported here). As in Study 1, these questions were then repeated with “the aver- age person of your sex and age in this country” as the target.

Conditional risk. Participants were first asked a conditional risk question that included a presumption of no dietary change: “How likely do you think you would be to get heart disease at some time in the future if you were to make no changes to the amount of fat in your diet?” Participants rated their responses on a 6-point scale ranging from 1 (extremely unlikely) to 6 (extremely likely). This was then followed by a second conditional risk question, which incorporated a pre- sumption of dietary change: “How likely do you think you would be to get heart disease at some time in the future if you were to reduce the amount of fat in your diet?’ The question was rated on the same 6-point scale.

Subjective likelihood of trying to reduce and of actually reducing fa t con- sumption (expected behavior). Participants were asked about their subjective likelihood of trying to reduce their fat consumption in the following year: “How likely do you think it is that you will try to reduce your fat consumption in the next year?” This was rated on a 6-point scale ranging from 1 (extremely unlikely) to 6 (extremely likely). The question was followed by another question asking participants about their subjective likelihood of actually achieving a change, “If you were to try, how likely do you think you would be to actually achieve a reduction in your fat consumption in the next year?’ which was rated on the same 6-point scale.

Procedure

Participants were sent a letter explaining the study, a consent form, the ques- tionnaire, and a prepaid return envelope. Once the questionnaire was returned, two further questionnaires (unrelated to this study) were sent to participants. Par- ticipants were each paid E6.00 (about $9.50) in total for taking part.

Results

A researcher unfamiliar with this research area assessed participants’ scenario responses in order to ascertain whether the instructions had been followed. Par- ticipants who did not respond according to the instructions were excluded from the analysis. This left 68 participants in the heart-disease condition, 76 in the reduce-fat condition, and 73 in the television control condition. Thus, the revised instructions were successful in ensuring satisfactory compliance rates in the reduce-fat condition.

IMAGINING AND EXPLAINING HYPOTHETICAL SCENARIOS 881

Subjective Likelihood of Experiencing Heart Disease

A 2 x 4 x 2 (Target: Self vs. Average Other x Condition: Heart Disease vs. Reduce Fat vs. Television Control vs. No Task Control x Conditional Risk: No Changes vs. Changes) MANOVA was computed. Conditional risk and target were within-subjects variables, and condition was a between-subjects variable. There were significant main effects both for target, F( 1,286) = 164.66, p < .001, and for conditional risk, F( 1, 286) = 550.26, p < .001. There was also a signifi- cant Target x Conditional Risk interaction, F( 1,286) = 42.44, p < .001, which indicated that the difference between ratings for self and average other were greater for the likelihood of heart disease if no dietary changes were made (Ms =

3.59 and 4.65) than for the likelihood of heart disease if fat consumption were reduced (Ms = 2.68 and 3.26).

There was no main effect for condition, F(3, 286) = 0.52, ns, nor any signifi- cant interactions involving the condition factor. Thus, there were no effects of imagining heart disease on the perceived likelihood of experiencing heart disease ratings.

Subjective Likelihood of Trying to Reduce and ofActually Reducing Fat Consumption

A similar 2 x 4 x 2 (Target: Self vs. Average Other x Condition: Heart Disease vs. Reduce Fat vs. Television Control vs. No Task Control x Expected Behavior: Trying vs. Succeeding Given Trying) MANOVA was computed. There were sig- nificant main effects for target, F(1, 286) = 1 5 5 . 8 2 , ~ < .001, and for expected behavior, F( 1, 286) = 3 1.09, p < .001. There was also a significant Target x Expected Behavior interaction, F( 1, 286) = 27.54, p < .001, which indicated that the difference between ratings for self and average other was less for the likelihood of trying to reduce fat consumption (Ms = 4.07 and 3.27) than for the likelihood of actually reducing fat consumption if an attempt were made (Ms = 4.55 and 3.32).

There was no main effect for condition, F(3,286) < 1, ns, but there was a sig- nificant Condition x Target interaction, F(3, 286) = 5.99, p = .001. In order to investigate this interaction, a series of one-way ANOVAs was computed on the condition factor at each level of the target factor (although there were no inter- action effects involving the expected behavior factor, separate analyses for the two levels of this factor are also reported, so as to show full details of the results).

A one-way ANOVA of subjective likelihood of oneself trying to reduce fat consumption was marginally statistically significant, F(3, 286) = 2.58, p < .06. Planned comparisons showed higher subjective likelihood ratings for participants in the reduce-fat condition ( M = 4.45) than for participants in the heart-disease condition ( M = 3.87), t(286) = 2.46, p < .05; in the television control condition ( M = 3.92), t(286) = 2.29, p < .05; and in the no-task control group ( M = 4.03), t(286) = 1.83, p < .05 (Table 2). A similar one-way ANOVA on the subjective

882 SPARKS ET AL.

Table 2

Subjective Likelihood of Heart Disease and Reducing Fat Consumption: Experiment 2

Imagine and explain

Heart disease Reduce fat Television No task (n = 68) (n = 37) (n = 74) (n = 74)

M SD M SD M SD M SD Subjective likelihood of heart disease if no dietary changes were made

Participantsa 3.53 1.07 3.80 1.25 3.53 1.29 3.47 1.42 Average otheF 4.63 0.69 4.72 0.85 4.60 0.91 4.62 1.00 Difference -1.10 1.11 -0.92 1.21 -1.07 1.33 -1.15 1.41

Subjective likelihood of heart disease if fat consumption were reduced Participantsa 2.57 1.01 2.76 1.11 2.79 1.22 2.58 1.24 Averageothera 3.21 1.06 3.24 1.01 3.27 1.03 3.30 1.09 Difference -0.63 1.11 -0.48 1.13 -0.48 1.31 -0.72 1.38

Subjective likelihood of trying to reduce fat consumption Participantsa 3.87 1.34 4.45 1.40 3.92 1.45 4.03 1.49 Averageothera 3.25 0.97 3.15 1.32 3.51 1.07 3.19 1.13 Difference 0.62 1.37 1.31 1.50 0.41 1.62 0.84 1.76

Subjective likelihood of actually reducing fat consumption, were an attempt to be made

Participantsa 4.34 1.15 4.87 0.88 4.36 1.21 4.60 1.11 Averageothera 3.40 1.00 3.15 1.20 3.51 1.07 3.26 1.19 Difference 0.94 1.39 1.72 1.47 0.85 1.39 1.34 1.64

aRated on a 6-point scale ranging from 1 (extremely unlikely) to 6 (extremely likely).

likelihood of the average other trying to reduce fat consumption revealed no sig- nificant effect, F(3, 286) = 1.49, ns.

A one-way ANOVA of subjective likelihood of oneself actually achieving a reduction in fat consumption (if an attempt were made) was also statistically sig- nificant, F(3, 286) = 3.77, p < .02. Planned comparisons showed that participants in the reduce-fat condition ( M = 4.87) gave higher ratings than did participants in the television control condition ( M = 4.36), t(286) = 2 . 8 9 , ~ < .05; and in the heart- disease condition ( M = 4.34), t(286) = 2.85, p < .05; but not than participants in

IMAGINING AND EXPLAINING HYPOTHETICAL SCENARIOS 883

the no-task control group (A4 = 4.59), t(286) = 1.52, ns. A similar one-way ANOVA on the subjective likelihood of the average other actually achieving a reduction in fat consumption revealed no significant effect, F(3,286) = 1.46, ns.

Discussion

Although there was no effect of condition on subjective likelihood of experi- encing heart disease, the focus on process in the revised instructions to the reduce-fat condition led to an increase in judgments of both likelihood of trying and likelihood of succeeding in reducing fat consumption. From the point of view of trying to induce behavior change, this is encouraging. It is also interesting to note, however, that the effects were not mediated by changes in risk perception.

The findings involving the manipulation of conditional and unconditional risk judgments suggest that participants accepted that there is room for reductions in their intake of dietary fat (hence the main effect, with lowered likelihood ratings if fat consumption were to be reduced). Nevertheless, participants perceived there to be even greater scope for such a reduction in the average person’s diet (hence the interaction). These questions thus reveal at least tacit awareness among participants that their current diet disposes them to greater likelihood of heart disease. Again, however, there was clear evidence that, overall, participants were comparatively unrealistically optimistic about their diets. They were also comparatively unrealistically optimistic about behavior, seeing themselves as more likely than average to both try to reduce their fat consumption and even more likely than average to succeed if they did try.

Thus, the revised instructions in the reduce-fat condition appear to have increased the ratings of both likelihood of trying to reduce fat consumption and likelihood of succeeding. However, they did not achieve this effect by altering ratings of the subjective likelihood of experiencing heart disease.

General Discussion

Contrary to findings and assertions elsewhere, in these experiments we found little evidence for an effect of imagination and explanation on likelihood (risk) judgments. This was true even with the revised instructions in the reduce-fat condition in Experiment 2. This failure goes against the grain of recent sugges- tions that imagination is one of the core cognitive processes underlying compara- tive unrealistic optimism. Theoretically, it raises questions about what was different in this study from those that have shown such effects.

In terms of risk judgments, therefore, the findings from both studies actually provide further evidence of the resilience of risk judgments and the robustness of comparative unrealistic optimism to attempts to debias. Participants who were asked to imagine themselves contracting heart disease typically did not increase

884 SPARKS ET AL.

their subjective likelihood judgments and remained just as comparatively opti- mistic as those in the control groups and those who were asked to imagine them- selves in the process of reducing their fat intake.

By way of contrast, in Experiment 2, the imagination task produced encour- aging increases in subjective likelihood of both trying and succeeding in reducing fat consumption. This is consistent with recent findings that mental simulations enhance the links between thought and action (Pham & Taylor, 1999). This is encouraging news for those who are interested in developing methods of promot- ing health-protective behavior, especially bearing in mind our use of a simple technique and an older, nonstudent sample.

From an applied perspective, the fact that these effects were not mediated by changes in risk perception is of less significance than the fact that they occurred. This pattern of findings suggests that intervention studies that focus directly on influencing people’s goal-oriented plans and behavioral change strategies might be more effective than those that focus on people’s perceptions of the risks that they face. Obviously, these effects of imagining behavioral changes are effects on behavioral expectations (or subjective probabilities), rather than on behavior, per se. Future research will need to investigate effects on measures of actual behav- ior. The relative effectiveness of different kinds of plans and the processes by which the imagination of these plans leads to beneficial consequences also merit investigation.

The findings of this study thus add to those suggesting that it is not necessary to target risk in order to facilitate behavior change. Clearly, perception of risk is only one of a range of factors influencing behavior, and the resilience of risk judgments to influence attempts makes them less than ideal as targets for applied interventions.

Theoretically, the question remains as to why the hypothesized changes in risk judgments typically were not forthcoming. The difficulty of imagining the health-threatening outcome (cf. Sherman et al., 1985), possibly partly because of its low subjective probability and the difficulty of constructing a clear visual image of this outcome, might have been a contributory factor. Future research might make use of imagining specific symptoms of heart disease as an alternative to imagining the causal factor (heart disease) underlying these symptoms. Moti- vational reasons for a reluctance to imagine the scenario because of the negative personal consequences of the event also should be considered (cf. Sherman, Nelson, & Steele, 2000). Other potentially important factors, such as the repeti- tion of the imagination and explanation task (Anderson, 1983) and the degree of perceived personal relevance possibly influencing judgment strategies (Schwarz, 1998), also merit attention.

In conclusion, our research can be added to the literature suggesting that attempting to induce behavior change by increasing risk judgments appears to be fraught with practical as well as ethical problems. Consequently, in the case of

IMAGINING AND EXPLAINING HYPOTHETICAL SCENARIOS 885

dietary behavior, this is currently not a strategy that we are able to endorse. Instead, our research adds weight to the suggestion that efforts to promote health through dietary change should focus directly on strategies concerned with the planning of dietary change behaviors and suggests that appropriate imagination tasks hold promise in this regard. The benefits of this strategy for other domains of health-related behavior also merit investigation.

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