Introduction
It has been estimated that approximately 132,000 cases of melanoma (the deadliest type of skin cancer) and between 2 and 3 million non-melanoma skin cancers are diagnosed world-wide each year (World Health Organization
2007). Ultraviolet (UV) exposure (i.e., to the sun and/or tanning beds) has been identified as a primary cause of all skin cancers (Parker et al.
1997; World Health Organization
2007). Despite evidence of increased
knowledge regarding the health risks of UV exposure (Baum and Cohen
1998; Robinson et al.
1997; The Cancer Council, Australia
2007), the incidence of skin cancer continues to rise at a rate of ~3% per year (American Cancer Society
2007). Further, a recent report suggests that melanoma rates have increased by 50% in recent years among young Caucasian women (Purdue et al.
2008), the same population that has displayed increased sun exposure and tanning bed use (Cokkinides et al.
2006; Lazovich and Forster
2005; Robinson et al.
1997). Interventions that are effective for increasing UV protection behaviors have the potential for significant impact on skin cancer incidence.
Recent work suggests that appearance-based interventions hold promise for motivating skin cancer prevention behaviors (Jones and Leary
1994; Gibbons et al.
2005; Mahler et al.
1997,
2003,
2005,
2006,
2007). Appearance-based interventions attempt to motivate sun protection behaviors by highlighting the link between sun exposure and appearance detractors such as wrinkles, age spots, uneven pigmentation, etc. Relative to a health-based message, emphasizing negative appearance consequences may better counteract the appearance-based motivation for sun exposure (i.e., getting a tan; Hillhouse et al.
1996; Hoegh et al.
1999; Jones and Leary
1994; Miller et al.
1990; Robinson et al.
1997; Turrisi et al.
1998).
One such appearance-based intervention utilizes UV facial photographs to highlight the uneven epidermal pigmentation that results from chronic UV exposure. Particularly when combined with information regarding photoaging (premature wrinkles and age spots due to UV exposure) and prevention techniques, randomized studies have demonstrated that the UV photo intervention increased UV protection behaviors among a variety of populations for up to a year (with effect sizes generally in the medium to large range; Gibbons et al.
2005; Mahler et al.
2003,
2005,
2006,
2007; Pagoto et al.
2003). Although the UV photo/photoaging information (UVP/PI) intervention is among the most effective sun protection motivators studied to date, there is room for improvement. One potential approach for enhancing the efficacy of the intervention may be through the inclusion of social comparison information.
Social comparison
There is by now extensive documentation of the frequency with which individuals compare their personal attributes (personality, physical appearance, academic performance/ability, etc.) with those of others, and of the effects of such comparisons on self-perceptions (Suls et al.
2002; Suls and Wheeler
2000; Wheeler and Miyake
1992; Wood
1989). Although Festinger’s (
1954) original social comparison theory emphasized that comparisons with others who are similar to oneself (on the dimension of comparison) are preferred, subsequent work has demonstrated circumstances that motivate upward comparisons with others who are known to be relatively better off (i.e., when seeking inspiration or information for self-improvement; Collins
1996; Wood
1989) and downward comparisons with others who are worse off (i.e., when motivated to self-enhance; Wills
1981). While the bulk of the previous work has examined the effects of social comparison in non-health contexts, there is some evidence from randomized studies to suggest that social comparison information also may impact the efficacy of health risk communications (Klein and Weinstein
1997). For example, information regarding how one’s own level of risk for a particular threat (disease or accident) compares to that of similar others has been associated with intrusive thoughts (McCaul and O’Donnell
1998), concern about the threat and intentions to take preventive action (Klein
2002), and future preventive behavior (Blalock et al.
1990). Also, experimental work has found that such comparative risk information can impact emotions, assessments of the safety of one’s behavior, and behavior change intentions (Klein
1997). In some instances, participants have actually shown greater sensitivity to comparative risk information than objective risk information (Klein
1997,
2003; Blalock et al.
1990). Lipkus and Klein (
2006), for example, found that individuals who were provided information regarding how their risk for colorectal cancer compared to others of the same age reported higher mean intentions to be screened for the disease than did controls or those provided only absolute risk information. Thus, interventions that include comparative risk information may be more effective at motivating protective behavior than those that only include objective or absolute risk information.
Overview of current experiment
The primary purpose of the present experiment was to determine the effects of including social comparison information on the efficacy of a well-established appearance-based sun protection intervention. Specifically, this experiment examined whether young adults who received photoaging information (PI) and viewed their UV photograph (UVP) would be more likely to modify their sun protection behaviors when they also saw the UV facial photos of three peers who either had more (downward comparison) or less (upward comparison) skin damage than themselves. This age group was chosen because young adults have been shown to be at relatively high risk for skin cancer due to their lack of sun protective behavior (Cokkinides et al.
2006; Robinson et al.
1997), and because melanoma rates are increasing at an alarming rate among this age group (Purdue et al.
2008). Participants were randomly assigned to one of four conditions: control, basic (UVP/PI) intervention alone, the basic intervention plus downward social comparison information, or the basic intervention plus upward social comparison information. Perceived susceptibility to photoaging, tanning cognitions, and future sun protection intentions were assessed immediately following the intervention. One month later, self-reported sun protection behaviors also were assessed via a surprise telephone follow-up.
Given extensive previous evidence of the efficacy of the basic UVP/PI intervention (Gibbons et al.
2005; Mahler et al.
2003,
2005,
2006,
2007,
2008), we expected that participants in any condition that included the basic intervention would exhibit greater sun protection intentions and behaviors than controls. However, our predictions regarding the effects of social comparison information were necessarily more tentative for a couple of reasons. First, very little previous work has manipulated upward and/or downward comparison information in a health risk context, and most of the literature that does exist has utilized hypothetical situations. For example, Klein (
2003) found that participants asked to imagine that their risk of causing an automobile accident was greater than average rated their driving safety lower than did those who imagined their risk to be less than average. In addition, French et al. (
2004) found that participants who were asked to imagine that their chances of developing a fictitious pancreatic disease were lower than their peers reported that they would be less disturbed/worried than did either those who imagined their risk to be greater or who were not given comparison information.
One of the few studies to our knowledge that manipulated social comparison information within a more realistic health promotion context assessed a 50–75 year old community sample for colorectal cancer risk factors before telling participants that their risk factors were or were not more numerous than average (Lipkus and Klein
2006); the results showed stronger intentions to complete a screening test among those told they had more than the average number of risks for colorectal cancer (i.e., upward comparison information) relative to those who were only provided with objective risk information (no comparison information). Closer to the present context, Hoffner and Ye (
2009) more recently found that exposure to a fictitious (but realistic) newspaper article which combined a gain frame message (i.e., focus on the potential benefits to health and to skin) for sun protection and a description of a skin-healthy individual increased participants’ intentions to use sunscreen relative to controls. By extrapolation, this suggests that adding UV photographs of peers with very little sun damage (upward comparison photos) to the basic intervention might increase sun protection intentions. Unexamined in previous work, however, is whether upward comparison information actually increases preventive behavior. Although behavioral intentions have long been implicated as potential precursors to behavior change (e.g., Ajzen
1991; Ajzen and Fishbein
1980), intentions are increasingly recognized conceptually and empirically as insufficient predictors of health behavior change, especially when the behavior involved is habitual (e.g., Rothman
2000; Schwarzer
2001). Thus although immediate intentions were of interest, we were especially interested in how upward comparison information affected later sun protective behavior.
Also unexamined in previous work is the effect of downward comparison information on preventive behaviors. Hoffner and Ye (
2009) found that a negatively framed message about the consequences of failing to sun protect (i.e., focusing on the risks to health and to skin), in combination with a negative exemplar (description of a person with precancerous skin lesions), increased intentions to use sunscreen relative to controls, perhaps because the negative exemplar serves as a sort of fear intervention that motivates efforts to avoid a similar outcome (Lockwood
2002). However, the limited effects of fear manipulations on longer term behavior change (Mongeau
1998; Sutton
1982), in combination with work suggesting the importance of peer comparisons (Klein and Weinstein
1997), led us to anticipate that downward comparison information might have a relatively undermining effect on longer-term sun protective behavior. That is, we thought that seeing vivid images of severe skin damage sustained by peers might produce relief (relative to the intervention alone), because it could be construed as indicating one’s current level of damage was less than that of others and thus one’s current level of sun protection was better than that of others. The upshot might then be to decrease the behavior- change benefits of the basic intervention (which lacks comparison information); such an undermining effect, should it occur, would be of practical significance to the extent that UV photos become more widely used to motivate sun protective behaviors.
In brief summary, we anticipated that the basic UV-photo intervention (which provides no peer comparison information) would produce greater immediate sun-protection intentions and subsequent self-reported sun protection behavior than a control condition and, based on the limited previous work, that these benefits would be increased by the addition of upward comparison photos (UV photographs of peers with very little sun damage) and decreased by the addition of downward comparison photos (UV photos of peers with a great deal of sun damage). We also expected that any effects of the interventions on sun protection behaviors would be mediated by effects on tanning cognitions, perceived susceptibility to skin damage, and sun protection intentions.
Discussion
To our knowledge this is the first experiment to examine how the provision of upward and downward social comparison information impacts health promotion behavior in an actual, as opposed to hypothetical, health risk situation. This study also differed from the existing literature in that the social comparison information was not delivered through explicit statements of relative risk, e.g., “your risk is greater than average”; instead participants were provided with images designed to implicitly convey better or worse status, specifically, less or more sun damage than a group of peers.
Within this context, we found social comparison information did not influence immediate cognitions (participants who received the basic intervention, which was a combination of UV photo and photoaging information, felt more susceptible, had less favorable tanning cognitions, and expressed greater intentions to sun protect than controls, regardless of whether they also received upward or downward comparison information) but did affect later sun protective behaviors. It is possible that more explicit social comparison information (e.g., “your risk is greater than average”), because it is less open to interpretation (and self-serving distortion) than non-labeled photos of others, would provide a more differentiated pattern of immediate cognitions. This can certainly be tested in future work. However, we suspect that the greater impact of social comparison information on later behavior than on immediate cognitions that we found may actually reflect the process of behavior change. That is, in the moment, what may be most salient to participants are their UV photo and the photoaging information (both of which tend to be rather shocking for participants). When first confronted with vivid evidence of one’s actual underlying skin damage and how one may eventually look to the naked eye, it is perhaps not surprising that all participants, regardless of whether they also saw photos of others, felt vulnerable and intended to take action. Even seeing others with more damage (downward comparisons) may initially provide cold comfort. In line with this, albeit anecdotal, we had a number of participants in the downward comparison condition make statements along the lines of, “I’m glad I’m not as bad as them, and I don’t want my face to get that bad…I need to make some changes.”
It is relatively easy of course to intend to change habitual behavior but much more difficult to make and maintain change (see discussions by Rothman
2000; Schwarzer
2001). We found no evidence, for example, that participants in any of the intervention conditions significantly changed how much time they spent in the sun (sun exposure) compared to controls, a null effect we have seen previously (e.g., Mahler et al.
2005,
2007) and that is perhaps not surprising given that the photoaging video emphasizes sun protection (e.g., sunscreen use) rather than the avoidance of sun exposure. We did find, however, that the basic intervention increased sun protective behavior during the subsequent 5 weeks, and that the addition of upward comparison information to the basic intervention did not significantly increase subsequent sun protection. In sharp contrast, the addition of downward comparison information effectively negated the benefit of the basic intervention to the point where protection levels were virtually identical to controls and were significantly lower than in the upward comparison condition.
Null effects of course must always be interpreted with caution, as it remains possible that other operationalizations (in this case of upward comparison information) could produce more substantial positive effects. That caveat aside, we found no compelling evidence to suggest that the simple addition of upward comparison peer information is likely to be a means by which to enhance the efficacy of the basic UV-photo intervention. As a practical matter, our results therefore indicate that the basic UV-photo intervention is relatively more cost-effective. Work in other, non-health areas has suggested upward comparisons can be inspirational if (and perhaps only if) individuals believe they can eventually attain a similar high level (e.g., Lockwood and Kunda
1997; Taylor and Lobel
1989; Testa and Major
1990). In the present case, participants’ own UV photos indicated permanent damage that they had already done to their skin, so it was literally impossible, no matter how much sun protective behavior they performed in the future, for those in the upward comparison condition ever to achieve the level of skin health depicted in the peer photos. Perhaps this immutable fact dampened the impact of the upward comparison peers. Additional research will be needed to determine if upward comparison information might be more beneficial if, for example, participants are led to believe that future sun protective behavior could reduce their existing damage to the levels of the upward comparison peers.
Future research will also be needed to determine the mechanisms by which the downward comparison information undermined the basic UV-photo intervention effects. As already noted, we found no evidence that seeing others who had worse damage at the time of the intervention left participants with more favorable tanning cognitions, or feeling less susceptible to sun damage or less intent on increasing sun protective behavior than intervention-only participants. However, as all intervention participants encountered the inevitable difficulties of actually altering habitual behaviors, those who had seen the downward comparison photos seem to have had more difficulty adopting protective behaviors. We speculate that with time, those with downward comparison information may have been able to take comfort by rationalizing that their previous sun habits had resulted in much less skin damage than the average person their age, and therefore that major changes were not absolutely necessary. Thus it may be that some time after initial exposure to threatening information (in this case, vivid evidence of one’s previously unrecognized skin damage) is generally needed before thoughts of downward comparison can gain traction, providing comfort and influencing behavior. It will also be important for future work to examine the emotional effects of downward versus upward comparison information. There is growing evidence that affect may play an important role in health behavior decision-making (Lawton et al.
2007; Trafimow et al.
2004). It is possible, for example, that the negative emotional impact of the intervention is muted when paired with downward comparison photos and this may make it subsequently more difficult to sustain intended sun protection efforts.
Methodological/interpretive issues
This experiment had several methodological strengths additional to randomization and statistical control of baseline status. First, all of the outcome measures had been utilized successfully in several previous studies, allowing for better integration of the present findings with the existing literature. Perhaps most important, this experiment went beyond the hypothetical scenarios often utilized in the comparative risk literature and beyond the assessment of only immediate cognitions and behavioral intentions by utilizing an actual health threat and assessing sun protection behaviors at a 5-week follow-up. Finally, participants were not aware of this follow-up in advance, thus reducing the possibility that they altered their behavior in anticipation.
The experiment of course also had methodological limitations. First, it was conducted in a region of the country where the sun shines an average of 263 days per year. Thus, it is not possible to determine whether the interventions would have similar effects in areas with different climates. Generalizability is also limited by the fact that the sample was largely female and Caucasian, and exclusively between the ages of 18 and 34. We would note however, as mentioned previously, that this is exactly the population that has been found to have the highest increase in melanoma rates in recent years (Purdue et al.
2008) and thus the population that is most in need of effective interventions.
An additional limitation is that the follow-up, although longer than most, still was fairly short-term and relied on self-reports of sun protection behaviors. Thus, it is not possible to determine whether the interventions would alter actual behavior over a longer period of time. Several factors mitigate these concerns, however. First, we have found significant correlations between self-reported sun protection behaviors and objective measures of skin color change in previous work (Mahler et al.
2006,
2007). Such results provide validation for the self-report sun protection measures and also weaken arguments that the current results might reflect response biases of some kind. Additionally, a recent study found that the basic intervention used in this study produced objective behavior change through a 1-year follow-up (Mahler et al.
2007), so there is some reason to believe the observed effects can outlast our 5-week follow-up period. That said, we would be the first to acknowledge that follow-up studies utilizing objective measures of sun protection over longer periods of time would be desirable.
Practical implications and conclusions
Given the significant role that UV exposure plays in the development of skin cancer (American Cancer Society
2007; Parker et al.
1997) and the tremendous costs associated with treating the disease (Houseman et al.
2003), an intervention that is effective in increasing sun protection has the potential for significant impact on skin cancer incidence and health care costs. This study adds to the already considerable evidence that both UV photos and photoaging information can significantly increase sun protection behaviors (Gibbons et al.
2005; Mahler et al.
2003,
2005,
2006,
2007,
2008). This study also suggests that the effects of the intervention may be mediated in part by combined changes in tanning cognitions, perceived susceptibility to skin damage, and sun protection intentions. Further, assuming the findings involving social comparison information are replicated, they potentially have important practical implications for structuring future sun protection interventions, and perhaps for health behavior communications in general. Often health risk information is novel, ambiguous, threatening, or otherwise difficult to interpret without some comparative information. This study suggests that downward comparison information, if readily available at the time risk information is given, does not necessarily negate the immediate, cognitive impact of the risk intervention but may nonetheless dampen later behavior change.
Acknowledgments
This research was supported by a grant from the National Cancer Institute. The authors thank Heather Butler, Shiloh Beckerley, Daniel Barron, and Nolan Kulik for their help in carrying out this project.