Study 2b aimed to provide a conceptual replication of the moderating effect of strong naturalness cues. We kept the product constant and varied the claim on the product. To generalize results, we chose a product category that can benefit from both increased naturalness (healthier nutrition) and increased artificiality (more effective energy provision): protein bars. In addition, we extended the inquiry to another product inspection context. Mirroring the situation of online shopping where consumers can zoom in on one product at a time, participants either saw a picture of the matte or glossy product on a screen. Finally, we assessed claim believability as another potential mechanism.
5.1 Method
Study 2b featured a 2 (packaging surface: matte vs. glossy) × 2 (naturalness claim: present vs. control) between-subjects design. Overall, 231 US mTurkers (female = 42%,
Mage = 34.1), who indicated that they consume protein bars at least several times per year, were selected for the study. Depending on the condition to which they were randomly assigned, participants evaluated one of four pack shots of a protein bar not available in the US (see
Appendix). The pack shots only differed with regard to their surface. The glossy pack shot was visibly glossy and held reflections. To achieve a matte look, we edited this shot and removed all reflections in the matte condition (see
Appendix). Because still images do not depict lighting (and therefore mattedness and glossiness) as accurately as actual objects (Artusi et al.
2011), a description of the wrapper (“The protein bar is packed in a matte/glossy wrapper”) reinforced this manipulation.
Participants in the control condition saw the visual slogan “All Power.” Participants in the natural claim condition saw the slogan “All Natural. All Power.” To generalize results to another measure of perceived food naturalness, we asked respondents to estimate the percentage of natural ingredients in the protein bar. Expected tastiness, purchase intention, and the manipulation check were assessed with the same items as in study 2a. To address whether packaging surface also affects the believability of the naturalness claim by subtly reinforcing it (c.f. Mazis and Raymond
1997),
2 we also assessed claim believability with the item “This protein bar delivers what it promises.” We also included an instructional manipulation check (c.f. Oppenheimer et al.
2009) and assessed personality differences in claim skepticism via the skepticism scale developed by Mohr et al. (
1998) but found that it did not affect any of our results and thus do not report it.
5.2 Results and discussion
Twelve inattentive respondents who failed the instructional manipulation check were removed from further analyses. As intended, the matte packaging was perceived as significantly more matte than the glossy one (Mmatte = 5.86, SD = 1.39 vs. Mglossy = 2.36, SD = 1.76; t(190.31) = − 15.97, p < .001, d = − 2.32).
A 2 × 2 ANOVA on perceived product naturalness yielded main effects of the naturalness claim and packaging surface qualified by a significant interaction term (
Fclaim(1,207) = 33.87,
p < .001, η
2 = .14;
Fsurface(1,207) = 4.02,
p = .046, η
2 = .02;
Finteraction(1,207) = 4.79,
p = .030, η
2 = .02). Reconfirming the claim manipulation, the protein bar featuring the naturalness claim was perceived to contain more natural ingredients (
Mnatural = 71.05,
SD = 23.74 vs.
Mcontrol = 53.14,
SD = 22.40) (see also Table
1). Moreover, the protein bar in the matte packaging was perceived to be more natural (
Mmatte = 65.18,
SD = 22.58 vs.
Mglossy = 59.17,
SD = 26.62). Notably, this effect of packaging surface only emerged in the control group. In the absence of a naturalness claim, the matte packaging surface boosted the perceived extent of natural ingredients to above 50% (
Mglossy = 46.24,
SD = 22.17 vs.
Mmatte = 59.39,
SD = 20.89;
t(101) = − 3.10,
p = .003,
d = − 0.62). In contrast, when a naturalness claim was present, surface had no effect on perceived naturalness (
t(106) = 0.13,
p = .900).
To test for a potential role of claim believability, we ran a 2 × 2 ANOVA on claim believability and found a marginally significant effect of surface only (Fsurface(1207) = 2.95, p = .087, η2 = .01; Fclaim(1,207) = 0.08, p = .774; Finteraction(1,207) = 2.04, p = .155). The matte package was perceived to deliver somewhat more believable claims than the glossy package (Mmatte = 4.86, SD = 1.10 vs. Mglossy = 4.60, SD = 1.05). When we controlled for believability as a covariate (p < .001), the main effect of surface on naturalness was attenuated (F(1,207) = 2.10, p = .149), but the interaction effect of packaging surface and claim remained highly significant (F(1,207) = 8.59, p = .004, η2 = .04).
In addition, we tested for potential downstream consequences of this moderated effect of surface on perceived naturalness. We replicated an indirect effect of surface on expected tastiness in a moderated mediation analysis (moderated mediation coefficient b = − 0.33; CI95 [− 0.64, − 0.03]). In the control condition, we observed an indirect effect of surface on expected tastiness via perceived naturalness (CI95 [0.11, 0.44]). We observed no such effect when the claim “All Natural.” was added (CI95 [− 0.23, 0.22]). There was no additional direct effect of surface on expected product tastiness (CI95 [− 0.37, 0.37]). Adding believability as a parallel mediator, we found that claim believability also predicts expected tastiness (p < .001) but neither mediates the effect of surface (moderated mediation coefficient b = 0.13, CI95 [− 0.04, 0.39]) nor alters the effect via perceived naturalness (moderated mediation coefficient b = − 0.27, CI95 [− 0.54, − 0.03]).
We found a similar moderated mediation for purchase likelihood as dependent variable (moderated mediation coefficient b = − 0.29, CI95 [− 0.60, − 0.03]). In the control condition, we observed an indirect effect of packaging surface on purchase likelihood via perceived naturalness (CI95 [0.09, 0.51]). Once a naturalness claim was added, surface had no indirect effect on purchase intention (CI95 [− 0.21, 0.19]). There was no additional direct effect of surface (CI95 [− 0.43, 0.43]).
Similar to the physically present ketchup and soda, we found that matte packaging can enhance perceptions of naturalness for a protein bar depicted online. In the absence of a naturalness claim, the matte packaged bar was believed to contain more natural ingredients than the glossy packaged bar, which translated into better expected taste and higher intentions to purchase. However, once we added a naturalness claim, these effects disappeared and packaging surface made no difference to consumer perceptions. Study 2b thus confirms that stronger signals of product naturalness serve as a relevant boundary condition. In addition, we found that claims on matte packages were considered to be more believable. This, however, did not drive the effect on perceived naturalness.