Study B.3 serves two purposes. First, it further examines the mechanism of relative importance of safety and potency. It is similar to study 2.3. However in study 2.3, I cannot know whether relative importance of safety and potency shifts because safety becomes more important and potency’s importance stays the same, potency becomes less important and safety’s importance stays the same, or each attribute’s importance changes. In this study, I estimate absolute importance of safety and potency as two indirect pathways in a mediation model. I show preventing increases natural preference because it both increases the importance of safety and decreases the
importance of potency. Second, I use all nine treatments and problems from study 2.1, and show that the mediation model holds for both medicines and household products.
Four hundred two U.S. participants from Amazon’s Mechanical Turk completed an online survey in exchange for monetary compensation (Mage = 37.8, SD = 11.6, 54.0% female).
As in study 2.3, each participant viewed one scenario, and in each scenario participants considered a case where they were preventing a target problem and a case where they were curing the same target problem. Through random assignment, participants saw one of the nine target problems from study 2.1 (vitamin B deficiency, scurvy, common cold, mold, mouth bacteria, metal stains, wood stains, clothing stains, pipe leaks). Scenarios were identical to study 2.3.
Participants indicated their preferences for the natural alternative when preventing and when curing the target problem (as in study 2.3). In addition, they completed four measures of attribute importance: potency when preventing, safety when preventing, potency when curing, and safety when curing. Scales ranged from 1 = not at all to 7 = extremely. Before completing attribute importance measures, participants were told that:
We are interested in how important the potency and the safety of the medicine are to you. Potency refers to how strong and powerful the medicine is. Safety refers to the degree of risk and the extent of side effects that the medicine might entail.”
Through random assignment, half of participants completed importance questions before preference questions and half completed them after preference questions.
Furthermore, through random assignment, half of participants considered curing before preventing and half considered preventing before curing. Finally, through random
assignment, half of participants indicated the importance of potency before indicating the importance of safety and half considered safety before potency. In addition, participants completed the same trait natural preference measures and demographic measures from study B.2A.
Results
There were no main effects or interactions with order of questions, except a small mediator order by scenario interaction on natural preference (p = .017) and a small mediator order by attribute order interaction on potency importance (p = .020),so I collapse across order.
First, I examined preferences for natural products. In a 2 (Treatment Purpose: Prevent, Cure) X 9 (Target Problem: Vitamin B Deficiency, Scurvy, Common Cold, Mold, Mouth Bacteria, Metal Stains, Wood Stains, Clothing Stains, Pipe Leaks) mixed ANOVA, natural options were more strongly preferred for preventing than for curing (F(1, 393) = 36.81, p < .001, ηp2 = .09). Additionally, the natural alternative was
preferred more strongly for some problems (F(8, 393) = 3.16, p = .002, ηp2 = .06). There was no interaction between treatment purpose and target problem (F(8, 393) = 1.18, p > .25). The effect of treatment purpose for each target problem is displayed in Table B.9A.
Next, I examined the importance of potency. In a 2 (Treatment Purpose: Prevent, Cure) X 9 (Target Problem: Vitamin B Deficiency, Scurvy, Common Cold, Mold, Mouth Bacteria, Metal Stains, Wood Stains, Clothing Stains, Pipe Leaks) mixed ANOVA on potency’s importance, potency was rated as less important when preventing (F(1, 393) = 7.95, p < .001, ηp2 = .15). Potency was considered more important for some target
decreased the importance of potency, but the magnitude of this effect varied across target problems (F(8, 393) = 2.29, p = .021, ηp2 = .05; see Table B.9B).
Finally, I examined the importance of safety. In a 2 (Treatment Purpose: Prevent, Cure) X 9 (Target Problem: Vitamin B Deficiency, Scurvy, Common Cold, Mold, Mouth Bacteria, Metal Stains, Wood Stains, Clothing Stains, Pipe Leaks) mixed ANOVA on safety’s importance, safety was rated as more important when preventing (F(1, 393) = 2.18, p < .001, ηp2 = .05). Safety was marginally more important for certain types of problems (F(8, 393) = 1.75, p = .086, ηp2 = .03). The effect of preventing on safety’s importance varied across target problems (F(8, 393) = 2.37, p = .017, ηp2 = .03; see Table B.9C).
In a (within-subjects) mediation analysis, I assessed the indirect effect of
treatment purpose on preference for natural medicine through two pathways: importance of potency and importance of safety. Because my experimental design was within- subjects, I used MEMORE in SPSS (Montoya and Hayes 2017). This analysis revealed significant indirect effects of the importance of potency (indirect effect = .15, 95% CI [.09, .23]) and the importance of safety (indirect effect = .07, 95% CI [.03, .12]).
Preventing (versus curing) an ailment reduced the importance of potency (apotency = -.45), and reducing the importance of potency increased the natural preference (bpotency = -.34). Preventing (versus curing) an ailment increased the importance of safety (asafety = .18), and increasing the importance of safety increased the natural preference (bsafety = .29). The importance of safety and potency accounted for 53% of the effect of preventing on natural preference (c = .42, p < .001; c’ = .20, p = .006). A mediation model using only household product scenarios yielded very similar estimates (indirect effect of potency =
.15, 95% CI [.07, .23]; indirect effect of safety = .13, 95% CI [.07, .22]; c = .51, p < .001,
c’ = .23, p = .011, 55% of total effect accounted for by indirect effects of safety and potency importance).