That’s too close! The role of product-body proximity in naturalness marketing Open Access

Major concerns emerge about the detrimental consequences of the consumption of unnatural products. The World Health Organization (2023), for instance, warns of the worrying increase in diet-related illnesses, such as heart disease, linked to the intake of highly processed food. Many consumers are therefore concerned about the consumption of highly processed products and ingredients (EIT Food, 2024), as they are unnatural and therefore potentially harmful (Stanziani, 2008). Such concerns are not limited to food products, but also extend to other fast-moving consumer goods. The European Consumer Organization (2023) has recently revealed that consumers are regularly exposed to hazardous substances through the use of cosmetics or hygiene products, among others. Reports like these are fueling a growing desire for the consumption of natural products.

The concept of naturalness can be defined as “little or no human processing” (Rozin, 2005), “found in nature” and “not involving anything made or done by people” (Cambridge Dictionary, 2024a). Naturalness is predominantly perceived as a positive and desirable attribute (Rozin, 2005; Rozin et al., 2012) and is considered to be superior to unnaturalness (Li and Chapman, 2012; Moscato and Machin, 2018; Meier et al., 2019). It describes the original state of a product and is associated with the terms “biological,” “healthy,” “plants” and “environment” (Rozin et al., 2012). Consumers prefer natural entities to those produced with human intervention due to the positive associations naturalness evokes (Rozin et al., 2004), for instance, that the respective product is healthy or safe (Rozin, 2005; Rubin and Brod, 2019). The preference for naturalness is substantial and prevalent in a number of product areas (Rozin et al., 2004).

In light of the positive perception of naturalness in consumers’ minds, many companies allude to naturalness in marketing their products in an attempt to make their products more attractive to consumers. This trend is particularly evident in the sector of fast-moving consumer goods, including food, body care and household care products (Statista, 2023a, 2023b). In the USA, for example, 17.6% of all food, 3% of all personal care and 0.8% of all household care products held a natural claim in 2017 (Statista, 2018). The share of products with natural claims has increased in all of these categories in recent years (Statista, 2018) and is expected to further rise due to the growing interest in naturalness.

The challenge for many marketers is to decide whether to follow this trend and to position their products as natural. While consumers often perceive natural alternatives as better, the allusion to naturalness is likely to be accompanied by varying degrees of success in the aforementioned sectors. There is evidence that consumers are more concerned about ingestible than about noningestible products (Rozin and Fallon, 1987). Moreover, literature on the sharing economy suggests that consumers are less likely to share goods that are used to prepare food than they are to share goods used distant from the body (Hazée et al., 2019). A similar pattern is detected in the literature on recycled products. Consumers are less willing to use a product made from recycled plastic bottles when it touches their skin compared to when it does not touch their skin (Meng and Leary, 2021). Hence, one factor that may play a vital role in the preference for naturalness is the product’s closeness to the consumer’s body when used. However, the product’s proximity to the consumer’s body has not yet been considered in this context.

In some cases, it may even be counterproductive for marketers to position products as natural. Consumers are aware that manufacturers face constraints in the product development process. They believe that, due to such constraints, a desired product attribute is inevitably compensated for by an undesired attribute (Chernev and Carpenter, 2001). This type of compensatory reasoning is termed the zero-sum logic (Chernev, 2007). In particular, consumers associate higher product sustainability with gentleness while they associate lower product sustainability with strength (Luchs et al., 2010). Hence, gentleness is perceived as a positive attribute that is counterbalanced by the negative attribute of lower strength. These associations lead to lower preference for sustainable products when strength is valued, which is known as the sustainability-liability effect (Luchs et al., 2010). A similar effect is also found in the particular context of naturalness. That is, consumers believe that natural products are safer but less potent than conventional products (Scott et al., 2020). While safety is a desired attribute in products that prevent an illness, such as food, potency is desired in curative products, such as medicine (Scott et al., 2020). As a consequence, consumers prefer naturalness more for food than for medicine (André et al., 2019; Rozin et al., 2004; Scott et al., 2020). It can be derived from this literature that the function a fast-moving consumer good is intended to fulfil may play a vital role in the preference for naturalness. Moreover, one characteristic that food and medicine have in common is that both product types are ingestible. Hence, even for one level of product-body proximity (in this case: close contact to the consumer’s body), there seems to be varying degrees of preference for naturalness. Product‐body proximity and the product’s function seem to have an interactive effect on the preference for naturalness in fast-moving consumer goods.

Despite the apparent ubiquity of naturalness in marketing, current research has not yet fully explored when consumers desire natural products. The aforementioned literature indicates that the product’s proximity to the consumer’s body and the product’s function might play a role in the preference for naturalness. So far, the analysis of the preference for naturalness was, however, mainly limited to single products [e.g. food supplements (Li and Chapman, 2012)] or to comparisons of products belonging to the same level of product-body proximity [e.g. high proximity in terms of food vs medicine (Rozin et al., 2004)]. An explanation for the variation in the preference for naturalness across a broad range of fast-moving consumer goods has not yet been revealed. Further knowledge of when consumers prefer naturalness is relevant for marketers, as it can protect them from unnecessary additional effort and disappointment due to unexpectedly poor sales. The first aim of our research is therefore to offer an explanation for the variation in the preference for naturalness across different categories of fast-moving consumer goods. To fill the gap in the existing literature, we divide fast-moving consumer goods into six categories based on product-body proximity (low, medium and high) and product function (nourishing and cleaning). We propose that the preference for naturalness across a broad range of fast-moving consumer goods can be estimated based on this categorization. Hence, we show that the preference for naturalness can be explained by product-body proximity and product function.

The second aim of our research is to examine why consumers value natural products. We analyze two potential reasons. First, consumers associate naturalness with cleanness. In particular, natural food is described as “clean” food (Asioli et al., 2017; Ingredion, 2014) and natural cosmetic products are known as “clean beauty” products (Rubin and Brod, 2019; Tran et al., 2022). Conversely, when using synthetic products, consumers may feel negatively contaminated with unnatural attributes. Previous literature suggests the presumption that the feeling of contamination may vary with product-body proximity (Castro et al., 2013; Rozin et al., 2008). Second, different fast-moving consumer goods have different impacts on consumer well-being. Food, for instance, is more closely linked to well-being than body care (Ares et al., 2014b). This may be due to the fact that different products address different consumer needs (Diener et al., 2018). Hence, the feeling of contamination and the product’s impact on well-being may explain why product naturalness is important to consumers. Further insights on this matter can guide marketers in their decisions.

The remainder of this paper is organized as follows. Section 2 presents a literature review on naturalness, product-body proximity, and product function to examine when consumers prefer naturalness. The hypotheses derived from this review are tested in our first study in Section 3. Section 4 presents a literature review on contamination and the impact a product can have on consumer well-being to examine why naturalness is an important attribute to consumers. The hypothesis derived from this literature review is tested in our second study in Section 5. Section 6 offers a general discussion and concludes. Based on our findings, we offer practical implications for marketers regarding naturalness marketing.

Naturalness is a vague concept that consumers broadly interpret as “little or no human processing” (Rozin, 2005). It can be defined as something that is “found in nature” and that does not involve “anything made or done by people” (Cambridge Dictionary, 2024a). A substantial body of previous literature has sought to elucidate consumers’ understanding of this attribute (see Part A of Table 1 for an overview of key literature on naturalness). A particularly critical factor in determining perceived naturalness is the level of human intervention (Rozin, 2005; Rozin et al., 2004). More precisely, chemical transformations tend to reduce perceived naturalness to a greater extent than physical transformations (Rozin, 2005). In particular, genetic engineering represents one of the highest levels of intervention and is therefore perceived as the opposite of natural (Rozin et al., 2012). Previous literature also found that small quantities of an additive that exhibits negative or unnatural characteristics have a significant detrimental impact on perceived naturalness (Rozin, 2005). Moreover, the processing of a substance is a more influential factor in determining its naturalness than the content (Rozin, 2005). The perception of naturalness is, however, not significantly diminished when combining natural-like substances (e.g. water from different sources; Rozin, 2005).

In marketing, the term “natural” is not officially regulated and therefore technically has no meaning [FDA (U.S. Food and Drug Administration, 2018)]. This lack of regulation leaves room for unwarranted expectations regarding natural products. Previous literature has revealed numerous positive expectations that consumers have toward them (e.g. Apaolaza et al., 2014; Schirmacher et al., 2023). The creation of positive expectations toward natural products is attributed to the halo effect (Thorndike, 1920) and is also known as the aura of naturalness (Berry et al., 2017). As naturalness is a vague concept, consumers use associations to interpret the meaning of the term. In particular, they interpret natural as “existing in or produced by nature,” “not made or caused by humans” and as “not having any extra substances or chemicals added” (Berry et al., 2017). Moreover, consumers perceive “green,” “sustainable,” “ethical” and “organic” to be closely related to naturalness (André et al., 2019; Scott et al., 2020). Due to these positive expectations and associations, consumers develop a “natural is better” heuristic (Li and Chapman, 2012; Moscato and Machin, 2018; Meier et al., 2019). They view natural products more favorably (e.g. Rozin et al., 2012). The belief that something is positive because it is natural is also known as the “appeal to nature” (Moore, 1922). In the acceptance of food products and food technologies, perceived naturalness is of particular importance (Román et al., 2017), hence of great significance (Oxford Dictionary, 2024).

Consumer preference for naturalness can be defined as the inclination to favor entities that are perceived as natural, as opposed to those that have been produced through human intervention (Rozin et al., 2004). Consumers prefer natural products for instrumental and ideational reasons, meaning that they believe in the functional and moral/aesthetic superiority of natural products, respectively (Li and Chapman, 2012; Rozin et al., 2004). The preference for naturalness manifests itself in higher intentions to purchase natural products (e.g. Rybak et al., 2021).

Previous literature indicates that it is necessary to consider a product’s closeness to the consumer’s body when used, i.e. a product’s proximity to the consumer’s body (see Part B of Table 1 for an overview of key literature on product-body proximity). Previous literature has shown that consumers are more concerned about products that are ingested or associated with ingestion than about products that are used distant from the body (Rozin and Fallon, 1987). For example, Castro et al. (2013) showed that disorganized shelves with limited product quantities have different effects on sales for ingestible vs noningestible products. For ingestible products (e.g. juice), sales decreased when the shelf had limited product quantity and appeared disorganized, but for noningestible products (e.g. fabric softener), sales increased (Castro et al., 2013). Similarly, Hazée et al. (2019) demonstrated that consumers are less likely to share goods that are used to prepare food (e.g. cheese fondue set) than they are to share goods used distant from the body (e.g. sander). Meng and Leary (2021) showed that consumers would rather not use a product that is made from recycled plastic bottles when it touches their skin (e.g. a T-shirt) compared to when it does not touch their skin (e.g. a carrying bag).

We follow Hazée et al. (2019) in labeling the product’s closeness to the consumer’s body when used as “product-body proximity.” However, while Hazée et al. (2019) distinguish between two levels of proximity (i.e. low and high), we add a third level to this concept to allow for a more nuanced view. We propose that products can be used in low, medium, or high proximity to the consumer’s body. Products with a low body proximity are intended for external use (e.g. household care products). They are applied to the consumer’s surroundings but are not intended to come into direct contact with the consumer’s body. Products with a medium body proximity are intended for semiexternal use (e.g. body care products). They are applied to the body (e.g. skin) but are not intended to enter the body. Products with a high body proximity are intended for internal use (e.g. ingestible products), meaning they are meant to enter the consumer’s body. Oral incorporation is the closest form of contact (Castro et al., 2013) and implies an internalized and prolonged exposure to the ingested product (McEntaggart et al., 2019). Importantly, consumers believe that they adapt the properties of the food they consume (Rozin and Fallon, 1987). We therefore expect that the preference for naturalness increases with product-body proximity:

As described above, we use three levels of product-body proximity to allow for a more nuanced view of the preference for naturalness across a comprehensive array of fast-moving consumer goods. While two levels can only reveal a linear relationship with respect to the outcome variable (e.g. preference for naturalness), the use of three levels allows for a more accurate reflection of reality as it permits the possibility of a semi- or non-linear relationship. We assume that the preference for naturalness does not increase equally with higher levels of proximity. Instead, we assume that the increase in preference for naturalness is stronger between low and medium proximity products than it is between medium and high proximity products. Consumers may perceive body care and ingestible products as more closely related to each other than to household care products due to the following reasons. Ingestible products can influence the consumer’s outward appearance and can therefore complement body care products to some extent. For instance, nutritional products such as certain foods and supplements can be consumed to enhance skin health (Faria-Silva et al., 2020). Such products are referred to as “nutricosmetics” and can also be designated as “beauty pills” or “oral cosmetics” (Anunciato and da Rocha Filho, 2012). Likewise, food-based ingredients are increasingly being incorporated into body care products. For instance, red fruit extract, black tea extract and caffeine can be found in commercial body care products due to their assumed skin care qualities (Faria-Silva et al., 2020). Consequently, food-based products are available for topical and oral applications (Faria-Silva et al., 2020). This convergence between ingestible and body care products may contribute to a perceptual alignment in the minds of consumers. In particular, consumers might perceive a greater discrepancy between household care and body care products than between body care and ingestible products.

Consumers may also perceive body care and ingestible products as more closely related to each other than to household care products due to their effects on the consumer’s body. Household care products are intended for external use and only indirectly affect the consumer’s body (e.g. through inhalation of chemicals from cleaning agents or accidental skin contact with cleaning agents). Contrary to this, body care and ingestible products both have a direct impact on the consumer’s body. More precisely, body care products are intended for use on the outer body and therefore have a direct effect on it, e.g. via skin absorption. Similarly, ingestible products are intended for oral intake, meaning they have a direct impact on the inner body, e.g. through digestion. Hence, while body care and ingestible products have a direct impact on the outer or inner body, household care products typically have a rather indirect impact on the consumer’s body (see, e.g. Isaacs et al., 2020). Due to this direct impact, the increase in preference for naturalness might be stronger between household care and body care products than between body care and ingestible products:

Apart from positive expectations (see Section 2.1), previous literature has also revealed negative expectations that consumers have toward sustainable, organic or natural products. For instance, sustainable products are expected to have a lower functional performance or worse aesthetics (Acuti et al., 2022; Lindgreen et al., 2009; Luchs and Kumar, 2017). Similarly, organic products are expected to have a worse appearance and a low durability (Vega-Zamora et al., 2014; Zanoli and Naspetti, 2002). Of particular significance to our research is the association of naturalness with lower potency or efficacy (Luchs et al., 2010; Pancer et al., 2017). One explanation for consumers’ negative expectations toward natural products in terms of potency is the zero-sum logic (Chernev, 2007). Consumers recognize that manufacturers are constrained in the product development process and consequently believe that positive attributes also come with negative attributes (Chernev and Carpenter, 2001). Consumers, therefore, assume that an intended focus on sustainability forces the company to reduce its focus on product quality (Newman et al., 2014). In particular, consumers expect sustainable products to be gentle and less potent (Luchs et al., 2010). Consequently, consumers prefer naturalness more for preventive (e.g. food) than for curative products (e.g. medicine) because they expect natural products to be less effective than their conventional counterparts (Scott et al., 2020). This is known as the “ethical = less strong” intuition (Mai et al., 2019) or as the sustainability-liability effect (Luchs et al., 2010). As a consequence, consumers, for instance, use a greater amount of natural disinfectant compared to an unnatural alternative to compensate for the perceived inferiority (Lin and Chang, 2012).

Based on this background, we expect the preference for naturalness to depend on the function of a product because different products come with different importance of gentleness/safety and strength/potency. By product function, we mean the primary purpose that a product is intended to serve or, in other words, the central task that a product was manufactured to fulfil. To determine when consumers value sustainability, Luchs et al. (2010) opted for the differentiation between “gentleness” and “strength.” In the context of our analysis, however, this differentiation is not suitable as fast-moving consumer goods cannot be accurately differentiated based on gentleness and strength. To illustrate this point, shampoo can be both gentle (e.g. baby shampoo; Luchs et al. (2010)) and strong (e.g. anti-dandruff shampoo). Therefore, the differentiation between gentleness and strength is more appropriate for different variants of products than it is for overarching categories. Similarly, Scott et al. (2020) differentiated between the attributes “safety” and “potency” to determine when consumers value naturalness. While this differentiation is applicable to the case of preventative (e.g. foods) and curative products (e.g. medicine), it is not suitable for the dichotomization of the whole range of fast-moving consumer goods. What better reflects a product’s primary function is the distinction between fast-moving consumer goods that are nourishing and goods that are cleaning. By definition, nourishing generally means to nurture and furnish with nutriment (Merriam-Webster, 2024b), whereas cleaning is defined as to rid of dirt or impurities (Merriam-Webster, 2024a). Hence, while nourishing products aim to provide desirable nutrients, cleaning products aim to remove undesirable dirt or bacteria. Drawing from the sustainability-liability effect (Luchs et al., 2010), we concur that consumers want nourishing products to be gentle and therefore have a higher preference for naturalness in such products. In contrast, consumers want cleaning products to be potent and thus have a lower preference for naturalness for such products. Nonetheless, safety concerns presumably increase with product-body proximity for both nourishing and cleaning products. Therefore, in addition to a main effect of product-body proximity (H1), we also expect a main effect of product function on the preference for naturalness:

The purpose of Study 1 was to test in a real-life setting whether consumer preference for naturalness increases with product-body proximity (H1), whether this increase declines with higher proximity (H2) and whether preference for naturalness is higher for nourishing than for cleaning products (H3).

Study 1 was a 3 (product-body proximity: low vs medium vs high) × 2 (product function: nourishing vs cleaning) within-subject design. We chose a within-subject design to obtain preference for naturalness in one product relative to the other products (see also Rozin et al., 2004). For the manipulation of product-body proximity, we distinguished between household care (= low), body care (= medium) and ingestible products (= high). To manipulate product function, we further categorized them into products that primarily aim to nourish and products that primarily aim to clean. Hence, we had to select six products that differed in terms of product-body proximity (low, medium and high) and product function (nourishing and cleaning). We searched for fast-moving consumer goods that were gender-neutral and known to the average consumer. Moreover, as it proved challenging to identify products that were similar across all six categories, we searched for nourishing and cleaning products that had the same area of application in each level of proximity. For the low proximity categories, we therefore chose the products surface nourishing oil and surface disinfectant. For the medium proximity categories, the products were hand cream and hand disinfectant. For the high proximity categories, the products were vitamins and antibiotics. We chose real-life stimuli (see Figure A1 in  Appendix 1) that were of the size and shape typically found in grocery or drug stores. For example, hand creams are typically offered in inverted elastic containers while liquid antibiotics are typically offered in small, brown glass bottles. Apart from the product names written in German and English on white labels, the presented product packaging was blank.

We conducted this study in-person during a major event on campus that aimed at informing visitors about the various research areas at the university. All adult English- and/or German-speaking visitors were eligible for this study. Participants who were interested in taking part in our study entered a separate room where they viewed all six products. They were then asked to rate their preference for naturalness for each of the presented products. We measured preference for naturalness with the item “Please indicate, whether you prefer the following products to be synthetic or natural” on a seven-point scale from 1 = “strongly prefer synthetic” to 7 = “strongly prefer natural” (see  Appendix 1 for the questionnaire). Our measurement of preference for naturalness was a single item based on Scott et al. (2020), who, however, did not report the precise wording of the question. The construct and the item used are consistent in terms of content, which supports face and content validity. However, conventional reliability or validity estimations are not applicable to single-item measures. We opted for a single-item measure despite this limitation as we were interested in a global and product-specific evaluation, but not in the various facets of naturalness (see Section 5.3 for a detailed discussion of single-item measures). Among the n = 135 participants who completed the study, 51.1% were female, their ages ranged from 19 to 76 years (M_age = 36.9, SD = 15.75) and 46.0% had at least a bachelor’s degree.

Figure 1 presents the mean preference for naturalness across all six product groups. We conducted a repeated measures analysis of variance to analyze the effect of product–body proximity and product function. The analysis reveals that the preference for naturalness differs across the levels of product-body proximity [F(2,268) = 17.53, p < 0.001]. The mean preference for naturalness is significantly different in the low vs medium proximity conditions (M_low = 4.19, SE = 0.11 vs M_medium = 4.63, SE = 0.10; p < 0.001) and marginally significant in the medium vs high proximity conditions (M_medium = 4.63, SE = 0.10 vs M_high = 4.80, SE = 0.10; p = 0.086). To analyze whether the difference in mean preference for naturalness is larger between low and medium proximity than it is between medium and high proximity, we further conducted a contrast analysis. Stated formally, we tested whether (M_medium − M_low) > (M_high − M_medium), which can be reformulated into −M_low + 2 M_medium − M_high > 0. Accordingly, we used contrast weights of m_low = −1, m_medium = 2 and m_high = −1. The resulting contrast estimate of C = 0.26 (SE = 0.15) is statistically different from zero [F(1,134) = 2.90, p = 0.091].

Preference for naturalness also differs across product functions [F(1,134) = 309.99, p < 0.001]. In particular, naturalness is preferred more for products that aim to nourish than for products that aim to clean (M_nourish = 5.66, SE = 0.08 vs M_clean = 3.43, SE = 0.13; p < 0.001).

As expected, consumer preference for naturalness increases with higher levels of product-body proximity, supporting H1. The preference for naturalness is lowest for products that are used distant from the consumers’ body. Hence, consumers are less concerned about products that do not touch their skin (e.g. household care products) than about products that do touch their skin (e.g. body care products). This corroborates Meng and Leary (2021), who show that consumers are less likely to accept a product that is made from recycled plastic bottles when it touches their skin compared to when it does not. The preference for naturalness is highest for ingestible products, meaning that consumers prefer naturalness, especially for products that are used in close contact with the body. This corresponds to Rozin and Fallon (1987), who show that consumers are particularly concerned about ingestible products. This finding is also in line with Castro et al. (2013), who show that consumers are less likely to purchase ingestible (vs noningestible) products from disorganized shelves. This finding is further consistent with Hazée et al. (2019), who show that consumers are less likely to share goods that are associated with food consumption.

The mean preference for naturalness is significantly different in the low vs medium conditions (p < 0.001) but only marginally significant in the medium vs high proximity conditions (p < 0.10). Hence, the increase in preference for naturalness levels off with increasing proximity. This difference is statistically significant, as indicated by the contrast analysis (p < 0.10) and as hypothesized in H2. This finding might be explained by the perceptual alignment in the minds of consumers due to the convergence between ingestible and body care products (Anunciato and da Rocha Filho, 2012; Faria-Silva et al., 2020). That is, while food-based products are available for topical (body care) and oral (ingestible) applications, they are less commonly found in household care products. As a result, consumers may perceive ingestible and body care products as more closely related to each other than to household care products. Hence, the preference for naturalness is more similar when comparing body care products to ingestible products than when comparing body care products to household care products. Moreover, while body care and ingestible products directly impact the outer or inner body, household care products typically do not have such a direct impact. This direct impact on the outer or inner body might also explain why the preference for naturalness is only marginally different in the medium vs high proximity conditions.

In technical terms, a lower p-value indicates greater statistical significance. A p-value that lies between 0.5 and 0.10 may indicate that a replication is needed to determine whether the results occurred by chance (Goodman, 2008). To rule out the possibility that the effects occurred by chance, we conducted a similar study (see  Appendix 2) to replicate the findings of Study 1. We conducted the Replication Study online with n = 98 participants and arrived at similar results. That is, consumer preference for naturalness increases with higher levels of body proximity, again in support of H1. The results also reveal that the increase in preference for naturalness levels off as proximity increases, in support of H2. More precisely, the mean preference for naturalness is significantly different in the low vs medium proximity conditions (p < 0.001) and in the medium vs high proximity conditions (p < 0.01). The respective contrast analysis reveals a contrast estimate that is statistically different from zero (p = 0.001).

In addition to the finding that consumer preference for naturalness increases with higher levels of product-body proximity, the results of Study 1 show that consumers prefer naturalness for products that are nourishing rather than cleaning, supporting H3. Consumers believe that naturalness implies safety (Scott et al., 2020) and value these attributes in nourishing products. On the other hand, consumers believe that naturalness implies a lower potency (Lin and Chang, 2012; Luchs et al., 2010; Scott et al., 2020). As potency is valued in cleaning products, naturalness is less desired for such products. Nonetheless, the preference for naturalness increases with product-body proximity also for cleaning products (see Figure 1). Consumers, therefore, appear to be unwilling to compromise safety for potency in cleaning products when it comes to products with medium and high body proximity (vs low).

Study 1 revealed that product-body proximity drives consumers’ inclination to favor naturalness. As the inclination toward naturalness is higher for nourishing than for cleaning products, we further focus on nourishing products. Previous literature revealed that naturalness is of particular importance within a specific category of nourishing products, namely, foods (Román et al., 2017). The question arises, why is naturalness an important attribute to consumers? In particular, why do consumers value naturalness more for products with higher body proximity?

One reason for the high naturalness importance for products that are used in high proximity to the body could be the feeling of contamination. Contamination occurs when a source comes into contact with a target (Argo et al., 2008). People believe that properties of one object can permanently transfer to another object even by brief contact (Rozin et al., 1986) and remain even after purifying the target (Rozin et al., 2015). The law of contagion (Rozin et al., 1986) states that a source can transfer some or all of its properties to the target through direct or indirect contact. A product can be contaminated when a consumer (potentially) touches it, it can contaminate other products or it can contaminate the consumer. Moreover, contamination can be positive or negative.

Previous literature has identified several effects that touch by other consumers can have on perceived product contamination. Positive contamination can occur when an attractive consumer of the opposite gender touches a product (Argo et al., 2008). It also occurs for objects once owned by famous personalities who consumers like (Newman et al., 2011). Such positive contamination increases product evaluations, purchase intentions, and even the willingness to pay for the respective product (Argo et al., 2008; Newman et al., 2011). Contrary to this, negative contamination leads to a lower product desirability. Previous literature has used disorganized shelves (Castro et al., 2013), the product position on the supermarket shelf (Argo et al., 2006), damaged packaging (White et al., 2016) and shared goods (Hazée et al., 2019) as cues for negative contamination. The consensus is that consumers have higher contamination concerns about items that are used in high proximity to their bodies due to the transfer of residues or germs (Hazée et al., 2019). Similarly, Rozin et al. (1989) showed that people expressed lower desirability of a laundered shirt that formerly belonged to a disliked person, compared to a neutral person.

In addition to the (potential) touch by other consumers that contaminates a product, a product can contaminate other products. To illustrate this point, products that are perceived as disgusting can exert a negative influence on evaluations of other products that are close by (Morales and Fitzsimons, 2007). Even in the absence of direct contact, consumers may form negative evaluations when they believe that a disgusting product has touched another product (Morales and Fitzsimons, 2007). In a more pronounced way, Rozin et al. (1986) demonstrated that a beverage became unappealing after brief contact with a dead cockroach, despite the fact that it had been sterilized.

Contamination can also originate from the product and transfer to the consumer. For example, Meng and Leary (2021) showed that consumers are less inclined to utilize a product made from recycled plastic bottles when it touches the skin (e.g. a T-shirt) due to the perceived contamination associated with recycled plastic bottles. In a study with various products, Abbey et al. (2015) observed that remanufactured products that are used closer to the body evoked higher levels of disgust. In particular, products used “around the consumer” (e.g. a remanufactured laptop) generated some disgust, while products used “on the consumer” (e.g. a remanufactured electric razor) generated more disgust and products used “in the consumer” (e.g. a remanufactured toothbrush) generated the highest levels of disgust (Abbey et al., 2015). They argue that products used closer to the body are more personal in nature. The belief that remanufactured products are tainted and dirty, and thus contaminated by the prior user, has more severe consequences the closer the products are used to the body (Abbey et al., 2015). This is presumably due to safety and health reasons.

In the context of natural products, we propose that positive contamination results from the association of naturalness with cleanness. For example, natural food is designated as “clean” food (Asioli et al., 2017; Ingredion, 2014). Such food is perceived to be free from chemicals and is instead perceived to consist of ingredients that are extracted from natural sources. Similarly, the clean beauty trend refers to the use of natural cosmetic products (Rubin and Brod, 2019; Tran et al., 2022). Thus, using natural products engenders a feeling of cleanness and purity in consumers. Conversely, using synthetic products may engender a feeling of uncleanness and impurity. Given the association of naturalness with cleanness (e.g. Asioli et al., 2017), we expect that natural products rather create a feeling of positive contamination. Conversely, we expect that upon using synthetic products, consumers feel negatively contaminated with unnatural and therefore undesired attributes that transfer from the product to the consumer. As ingestible products affect the most inner part of the body and are more likely to result in disease than non-ingestible products, consumers have high contamination concerns for products that are ingested (Castro et al., 2013; Rozin et al., 2008). Drawing from Abbey et al. (2015), products used closer to the body are perceived as more personal in nature. Therefore, the feeling of contamination when using synthetic products might be more prevalent for products that are used closer to the body. Hence, in comparison to ingestible products that primarily affect the inner body, the feeling of contamination is presumably lower for body care products because these products primarily affect the outer body. Further, the feeling of contamination is presumably lowest for household care products because these products primarily affect the consumer’s surroundings.

An additional potential explanation for the high naturalness importance for products used in high body proximity could be the impact that a product has on consumers’ perceived well-being. In general, well-being can be defined as a state of feeling happy and satisfied (Cambridge Dictionary, 2024b). While the concept of well-being can refer to specific aspects of life or to life as a whole (Diener et al., 2018), we focus on well-being that arises from the use of consumer goods. Research on consumer well-being in general has grown in the past few years; however, research on the influence of specific fast-moving consumer goods categories on well-being remains scarce. Most important to our research is the finding reported by Ares et al. (2014b). In response to the question of which factors impact consumer well-being, 39% of all respondents mentioned foods and 7% mentioned personal appearance (including body care). Notably, household care or similar terms were not mentioned at all (Ares et al., 2014b). The reason for the strength of these associations may be the fundamental role of food as a basic need that strongly impacts well-being when satisfied (Diener et al., 2018). Indeed, research findings indicate a strong correlation between well-being and the consumption of food products (e.g. Apaolaza et al., 2018; Ares et al., 2014a; Davison et al., 2021; Ocean et al., 2019). The consumption of food affects physical and psychological health and fulfils one of the basic human needs, which, in turn, affects perceived consumer well-being (Diener et al., 2018). Previous literature shows that, in particular, the consumption of vitamins and fresh, natural (Ares et al., 2014b), organic (Vega-Zamora et al., 2014) and delicious food (Apaolaza et al., 2018) increases consumer well-being. For instance, heavily processed food can induce feelings of fatigue, whereas the consumption of fruit and vegetables refreshes. Compared to food, a smaller proportion of consumers associate body care with well-being (Ares et al., 2014b). Research on body care products shows that such products can contribute to health and help consumers look and feel better, overall contributing to well-being (Cosmetics Europe, 2017). In contrast, household care products rather indirectly impact well-being. For instance, consumers feel more comfortable in their domestic environments after the use of household care products. Given the strong correlation between food and well-being compared to body care or household care products, consumers may perceive naturalness as important, particularly for ingestible products. Body care and household care products appear to exert a comparatively lower impact on consumer well-being.

In light of the aforementioned evidence, we argue that synthetic products can evoke stronger feelings of contamination when used in medium or high proximity to the body (vs low), which, in turn, increases naturalness importance. We further argue that products used in medium or high (vs low) proximity to the body increase naturalness importance due to their stronger impact on consumer well-being:

The objective of Study 2 was to examine why consumers value naturalness more for products with higher body proximity. In particular, we aimed to test the mediating effect of the feeling of contamination and the product’s impact on well-being on naturalness importance, as hypothesized in H4a and H4b.

Study 2 was a one-factorial (product-body proximity: low, medium and high) between-subjects experiment with random assignment. To operationalize the different levels of proximity, we searched for a stimulus that can be used as a household care product, applied to the body and ingested. Moreover, the product should not be a single-ingredient product typically associated with naturalness (e.g. olive oil or coconut oil). Instead, it should be available in both a natural and an unnatural version. As oil in general is one of the few products that met the aforementioned criteria, we selected furniture oil for the low, body oil for the medium and cooking oil for the high product-body proximity condition. Participants were randomly presented with one of the three products and were asked to imagine that they wanted to purchase it (see  Appendix 3 for the questionnaire). We included a stimulus of the respective oil product in a transparent bottle with a fictitious brand to avoid brand confounds (see Figure A3 in  Appendix 3).

We measured naturalness importance using the single-item measure “How important is it to you that [furniture/body/cooking] oil is natural?” on a seven-point scale (1 = “not at all important” to 7 = “very important”). The impact on well-being was measured using the single item “How much does the use of [furniture/body/cooking] oil impact your well-being? If you do not use [furniture/body/cooking] oil, please imagine how much it would impact your wellbeing.” on a seven-point scale (1 = “very weak impact” to 7 = “very strong impact”). Despite the fact that conventional reliability and validity tests are not possible with single-item measures, we adapted these measures for the following two reasons. First, while well-being and naturalness are multidimensional constructs, including all dimensions was not relevant for our purposes. Second, previous literature does not offer scales that fit the objectives of our study or relate to our product-specific context (see, e.g. Román et al., 2017). Developing new scales was beyond the scope of this research. Hence, we adapted single-item measures to capture a context-specific evaluation of overall naturalness importance and impact on overall well-being. Our items align with the constructs in terms of content, thereby supporting face and content validity. We adapted the contamination measure from Meng and Leary (2021) but made adjustments to both the question wording and the number of items. Regarding the former, Meng and Leary (2021) asked participants to rate a product in terms of 22 items that cover various constructs (i.e. attributes or associations of ability, contamination, disgust, haptic, image and reputation). We deviated from their rather general question wording and specifically asked respondents, “How would you feel when using synthetic [furniture/body/cooking] oil?.” Regarding the latter, Meng and Leary‘s (2021) contamination measure consisted of four bipolar items (pure–contaminated, clean–dirty, natural–artificial and safe–dangerous). From their measure, we retained only the two items that were directly relevant and applicable to our focal context (i.e. item 1: 1 = “pure” to 7 = “contaminated”, item 2: 1 = “clean” to 7 = “dirty”). This two-item measure captures a narrow, core evaluative aspect of contamination and does not encompass the conceptual breadth captured by Meng and Leary’s (2021) nuanced measure. We evaluated reliability and validity of this measure of feeling of contamination. As it consists of two items, we calculated the Spearman-Brown coefficient to test reliability (Eisinga et al., 2013) and arrived at a value of ρ = 0.862. Moreover, we observe a high Pearson correlation between the two items [r_{contaminated_dirty} = 0.757, t(207) = 16.66, p < 0.001], which indicates convergent validity. The low Pearson correlations between the item for impact on well-being and the two items of feeling of contamination [r_{well-being_contaminated} = −0.193, t(207) = −2.83, p = 0.005 and r_{well-being_dirty} = −0.227, t(207) = −3.36, p < 0.001] indicate that the constructs are related but conceptually distinct. To control for participants’ attention, we asked them to “[p]lease choose ‘disagree’” on a scale from 1 = “strongly disagree” to 7 = “strongly agree.” The survey concluded with sociodemographic questions.

We recruited participants from prolific (see Peer et al., 2017) to take part in our study for a small compensation. All English-speaking adults were eligible to take part in this study. After excluding two participants due to failed attention checks, we arrived at n = 209, of which 49% were female. Their ages ranged from 18 to 60 years (M_age = 27.04, SD = 7.66), and 64.2% had at least a bachelor’s degree.

The mean values of each variable considered in this study increase with product-body proximity. The mean naturalness importance is M_low = 4.45 (SD = 1.79) in the low, and increases in the medium (M_medium = 5.18, SD = 1.58) and high proximity condition (M_high = 5.41, SD = 1.61) (see Figure 2). Similarly, the mean feeling of contamination is M_low = 3.92 (SD = 1.32) in the low, and increases in the medium (M_medium = 4.15, SD = 1.22) and high proximity condition (M_high = 4.77, SD = 1.57). The perceived impact on well-being is M_low = 3.27 (SD = 1.61) in the low, and increases in the medium (M_medium = 4.43, SD = 1.42) and high proximity condition (M_high = 4.87, SD = 1.74).

To assess the effects of product-body proximity on naturalness importance via feeling of contamination and impact on well-being, we conducted a parallel mediation analysis (PROCESS Model 4; Hayes, 2018) with 10,000 bootstrap samples. The auxiliary regressions are presented in Table 2. Compared to the low proximity product, the medium proximity product has no significant effect and the high proximity product has a significantly positive effect on the feeling of contamination. Moreover, compared to the low proximity product, both the medium and high proximity products have a significantly positive impact on well-being. Naturalness importance is affected by the feeling of contamination and impact on well-being, but not by product-body proximity.

Overall, the indirect effect of proximity on naturalness importance via the feeling of contamination is significant in the high proximity (IE = 0.16, SE = 0.09, 95%CI = [0.02, 0.36]) but not in the medium proximity condition (IE = 0.04, SE = 0.05, 95%CI = [−0.04, 0.15]) (see Figure 3). The indirect effect via well-being is significant in both the medium (IE = 0.48, SE = 0.14, 95%CI = [0.24, 0.77]) and the high proximity conditions (IE = 0.66, SE = 0.17, 95%CI = [0.36, 1.04]).

The results of Study 2 partially support H4a, which posits that the feeling of contamination when using a synthetic product mediates the effect of product-body proximity on naturalness importance. Participants have heightened feelings of contamination when using a synthetic ingestible product compared to using a synthetic household care product. The general relevance of contamination in the context of product-body proximity is consistent with the findings of Hazée et al. (2019) and Meng and Leary (2021). However, the feeling of contamination when using a synthetic body care product (vs household care product) is not significantly higher. That is, we do not find that merely the contact with a consumer’s body activates feelings of contamination. Meng and Leary (2021) showed that consumers have stronger feelings of contamination toward recycled plastic bottles when the final product touches (vs not) the consumers’ body. In the context of natural products; however, it is not the close contact but the ingestion of synthetic products that significantly increases contamination concerns. One potential explanation for this discrepancy is the choice of focal products. While Meng and Leary (2021) used recycled plastic bottles, we used oil as the focal product to assess consumers’ feelings of contamination. Recycled plastic might be generally perceived as unclean, which leads to a significant difference in whether it is worn or carried. Contrary to this, synthetic oil is not perceived as unclean per se, but only for cooking oil (i.e. the mean values are close to 4 = “neither/nor” in the low and medium proximity conditions).

The results of Study 2 fully support H4b, stating that a product’s impact on well-being mediates the effect of product-body proximity on naturalness importance. Consumers value naturalness, especially for products that are used in medium and high proximity to the body because they have a stronger impact on well-being than products that are used distant from the body. This is in line with previous research that found a strong link between well-being and the consumption of food products. This also corroborates Ares et al. (2014b), who found that consumers associate well-being especially with foods and to some extent with body care but not with household care.

The results reveal a partially low proportion of explained variance, as indicated by the R² (see Table 2). In particular, the explained variance in the feeling of contamination by product-body proximity is as low as 0.06, while the explained variance in the impact on well-being by product-body proximity is 0.16. The R² of naturalness importance, as explained by product-body proximity, feeling of contamination and impact on well-being has, compared to the previously mentioned R² values, a higher value of 0.24. One explanation for the rather low values of R² is that we have not included gender or education as control variables. These variables do increase the R² value (see  Appendix 4), but only slightly. However, the data stems from a study with an experimental design and our goal was to assess whether the chosen explanatory variables have a significant effect on the dependent variables.

In this study, we predominantly used single-item measures. There are relevant arguments in favor of such measures. One advantage is the lower respondent burden. In particular, single items reduce cognitive load, avoid redundancy, and are less time-consuming (Allen et al., 2022; Gardner et al., 1998). Lower respondent burden results in higher completion rates. Another advantage is that single items have a lower risk of construct contamination (Allen et al., 2022). While multi-item scales may cover various dimensions of a construct, there is also a risk of including items related to other concepts. As single items do not cover various dimensions, they carry a lower risk of such construct contamination (Allen et al., 2022).

However, the use of single-item measures has been heavily discussed among scholars as it also has some notable disadvantages. One disadvantage is the reliability estimation. In the case of multi-item scales, reliability can be assessed through the calculation of Cronbach’s alpha, for example. However, given the absence of corresponding items that capture the same construct, reliability estimation is challenging for single-item scales (Allen et al., 2022). Other indicators, such as the test-retest reliability, need to be computed (Spörrle and Bekk, 2014). This, however, is a more unwieldy process. Another disadvantage is that a single item cannot address the various dimensions of a complex construct (Allen et al., 2022). A single item might be insufficient in capturing a personality trait, for example.

Nevertheless, extant literature demonstrates that using single items to arrive at an overall evaluation for a complex construct can be equally efficacious, or even superior, to using a multi-item measure that attempts to consider the various facets of this complex construct. For instance, Cheung and Lucas (2014) as well as Jovanović and Lazić (2020) found that single-item measures on life satisfaction perform very similarly compared to the multi-item satisfaction with life scale. The main results were virtually identical regardless of which measure was used. Scarpello and Campbell (1983) demonstrated that overall job satisfaction is best captured with a single direct question (“Overall, how satisfied are you with your job?”). Similarly, in their comparison of single- and multi-item measures of attitude toward an ad and attitude toward a brand, Bergkvist and Rossiter (2007) found no difference in predictive validity. Hence, even though multi-item scales are often preferred, especially for complex constructs (Diamantopoulos et al., 2012), single items are often as valid and reliable as their multi-item counterparts (Allen et al., 2022).

For our study, we deliberately selected single-item measures despite the fact that they do not allow conventional assessments of reliability and validity to capture global and product-specific evaluations. As previously stated, our items correspond to the constructs in terms of content, which supports face and content validity. Moreover, the findings revealed that the single-item measures vary systematically across the experimental conditions and are related to other variables in a manner consistent with theoretical predictions. For instance, evaluations of naturalness importance vary systematically depending on the levels of product-body proximity and are positively linked to evaluations of feeling of contamination and impact on well-being. These patterns are consistent with the theory presented in Sections 4.1 and 4.2 and provide supporting evidence for the validity of the selected single-item measures.

In light of the major concerns about the adverse effects caused by unnatural products, consumers are demonstrating a growing inclination to favor natural alternatives, that is, products that have undergone a low level of human intervention (Rozin, 2005; Rozin et al., 2004). In response to this, marketers from diverse sectors allude to naturalness in an effort to enhance the appeal of their products. This naturalness trend has sparked interest among many researchers. Despite the growing literature on naturalness, some questions remain unanswered. Most importantly, it is crucial to reveal what drives the preference for naturalness. Previous literature has shown that consumers perceive naturalness as a desirable attribute (Rozin, 2005; Rozin et al., 2004) that is superior to unnaturalness (Li and Chapman, 2012; Moscato and Machin, 2018; Meier et al., 2019). However, in some cases, it might be counterproductive to position products as natural. While consumers often perceive natural alternatives as better, the allusion to naturalness is likely to be accompanied by varying degrees of success, depending on the product category. Previous literature has not yet explained when consumers value naturalness in fast-moving consumer goods and why this is the case. To assist marketers in navigating the decision of whether to position their products as natural, our objective was to address this gap in the existing literature.

This research contributes to the naturalness literature. In the analysis of the preference for naturalness, previous literature has mainly focused on individual products [e.g. food supplements in Li and Chapman (2012); peanut butter in Berry et al. (2017); perfumes in Apaolaza et al. (2014)] or compared products of one level of product-body proximity [e.g. high proximity in terms of food and medicine in Rozin et al. (2004) and Scott et al. (2020)]. We analyze consumer preference for naturalness within the context of fast-moving consumer goods across six product categories based on a product’s proximity to the body (low vs medium vs high) and a product’s function (nourishing vs cleaning). To the best of our knowledge, we are the first to consider a broad range of fast-moving consumer goods (i.e. ingestible, body care and household care products) in the analysis of the preference for naturalness. We hereby provide a more nuanced view of the preference for naturalness across fast-moving consumer goods compared to previous research.

We add to the literature by examining when and why consumers value natural products. Addressing the prior (i.e. when), we show that a product’s proximity to the consumer’s body drives the preference for naturalness and naturalness importance. Previous literature showed that the body proximity to which the final product is used influences the acceptance of recycled plastic (Meng and Leary, 2021), the willingness to share goods (Hazée et al., 2019) and the likelihood of purchasing a product from a disorganized shelf (Castro et al., 2013). We add to the literature by showing that product-body proximity moreover influences consumers’ inclination to favor natural products. We thereby introduce the concept of product-body proximity to the naturalness literature and reveal that a higher level of body proximity increases the preference for naturalness and naturalness importance. Furthermore, while previous literature on product-body proximity distinguished between low and high levels, we add a medium level to allow for a more nuanced and comprehensive analysis. Our findings show that, in the context of naturalness, the distinction between three (instead of two) levels of product-body proximity provides crucial insights. The preference for naturalness does not increase equally across higher levels of product-body proximity. Instead, the increase is higher between the low and medium proximity than it is between the medium and high proximity. Accordingly, the concept of product-body proximity enables a more nuanced analysis when considering a higher number of levels.

Moreover, previous literature revealed that consumers value naturalness or sustainability when they aim for gentleness and safety, while consumers do not value naturalness when they aim for strength and potency (Luchs et al., 2010; Scott et al., 2020). The broad range of fast-moving consumer goods considered in our research, however, cannot be accurately differentiated based on gentleness and strength or safety and potency. Therefore, we differentiate products based on their primary function to nourish or to clean to determine when consumers value naturalness. This dichotomization of products into nourishing and cleaning ones overlaps with the dichotomization applied in prior research. In particular, nourishing products can be gentle and safe, whereas cleaning products can be strong and potent. The important difference is that a product (e.g. shampoo) can be both gentle and strong, depending on the product variant (e.g. baby shampoo vs anti-dandruff shampoo), while the product’s primary function is either to nourish (e.g. hair oil) or to clean (e.g. shampoo). Based on this dichotomization and drawing from the sustainability-liability effect (Luchs et al., 2010), we show that naturalness is valued in products that aim to nourish but is less desired for products that aim to clean.

We combine the two drivers, product-body proximity and product function, to explain the variation in the preference for naturalness. The preference for naturalness follows a pattern based on the categorization of fast-moving consumer goods into those used in low, medium or high proximity to the body in combination with their aim to nourish or clean. We also show that, across both nourishing and cleaning products, the positive correlation between product-body proximity and the preference for naturalness is stable. This indicates that consumers are not willing to compromise potency, which is valued in cleaning products, with safety, which is valued especially in products used in high proximity to the body. We tested the effect of product-body proximity and product function on the preference for naturalness in a natural setting with real-life stimuli (Study 1) and replicated the findings in a similar study online (Replication Study). Moreover, we tested the effect of product-body proximity on naturalness importance with nourishing products in an online experiment (Study 2). The effect of product-body proximity remains stable across the two related constructs, preference for naturalness and naturalness importance. We hereby offer a consistent explanation of when consumers value natural products.

Addressing the underlying mechanism behind the positive effect of product-body proximity on consumers’ inclination to favor naturalness (i.e. why naturalness is important), we reveal two relevant mediators. Previous literature revealed that feelings of contamination occur especially for ingestible products (Castro et al., 2013; Rozin and Fallon, 1987) and are higher for products that touch the skin (vs not; Meng and Leary, 2021). We show that consumers feel contaminated when using ingestible products that are synthetic. Consumers value naturalness for nourishing products used in high body proximity (compared to low) because synthetic alternatives cause a feeling of contamination. We further show that natural products are linked to well-being. A product’s impact on consumer well-being explains the positive effect of product-body proximity on naturalness importance. Products used in high proximity to the body have a higher impact on consumer well-being, which, in turn, increases naturalness importance. Ingestible products (e.g. cooking oil) also have the highest impact on consumer well-being, followed by body care products (e.g. body oil).

Our findings have a number of important implications for marketers. By categorizing fast-moving consumer goods based on their proximity to the body and their function, marketers can better assess how they should position their products in terms of naturalness. In other words, marketers can evaluate consumer valuation of naturalness based on product-body proximity and product function. Consumers value naturalness more in products that are used in higher proximity to the body and they value naturalness more in products that aim to nourish, but less for products that aim to clean. Products that fall into the nourishing category are, for example, vitamins, cooking oil, hand cream, body oil and surface oil. Hence, marketers of nourishing products should follow the naturalness trend and position their products as natural goods. Especially nourishing products that are used in medium or close body proximity should be positioned as natural. Contrary to this, naturalness is less desired for cleaning products, especially for those that are used far away from the body. Products that fit this description are household cleaners like surface disinfectants, for example. Marketers of cleaning products might feel tempted to follow the naturalness trend. However, our findings suggest that marketers should avoid naturalness cues for cleaning products. This can save them from unnecessary additional effort and unexpectedly low sales.

As consumers feel contaminated when consuming products that are synthetic, marketers of synthetic products should aim to reduce consumers’ contamination concerns. This is especially noteworthy for ingestible products, for which the feeling of contamination when using a synthetic alternative is especially high. Moreover, as naturalness importance increases with products used in medium and high proximity to the body due to a higher impact on consumer well-being, marketers of body care and ingestible products should emphasize their product’s impact on well-being. This is recommendable as consumers perceive these products to have a relatively high impact on their well-being. However, in light of their rather weak impact on consumer well-being, the emphasis on well-being appears to be less important in the marketing of household care products. Summing up, marketers of high body-proximity products should address both feelings of contamination and impact on well-being, whereas marketers of medium body-proximity products should solely focus on impact on well-being.

Our studies have limitations that set the stage for future research opportunities. First, our measurement choices constitute a limitation. Due to the reliance on single-item measures and the use of an abbreviated contamination scale, the underlying constructs are captured with limited precision and breadth. For example, our single-item measure for preference for naturalness does not capture distinct dimensions such as “ingredients used” (e.g. a product is free from artificial ingredients) and “production process” (e.g. a product has been minimally processed; see Román et al., 2017). When interpreting the results, it should be considered that our results refer to overall evaluations. Future research could build on this work by employing multi-item measures to assess the effects found in this research in greater depth. For example, do the observed effects of product-body proximity on preference for naturalness generalize across the various dimensions of naturalness? Are certain naturalness dimensions more relevant than others in this context?

Second, the choice of products represents a limitation. We acknowledge that the products compared in our studies are inherently different. The choice of products was driven by the manipulation of product-body proximity (in Studies 1 and 2) and product function (in Study 1). In Study 2, the products were all types of oil, but they might still be perceived as containing different ingredients. Furthermore, our analysis is limited to fast-moving consumer goods. Future research should investigate the effect of product-body proximity and product function in the category of durable goods. For example, fabrics can be composed of natural fibers, synthetic fibers or blends of both. It would be beneficial to explore consumer preference for natural fabrics across newly defined levels of product-body proximity. Consumers might be more accepting of synthetic materials in jackets, which do not come into direct contact with their skin, than in undergarments. If this turns out to be the case, what mechanisms underlie this effect? Moreover, fabrics can have different attributes. Consumers might value gentleness in products such as bed linens or baby clothing, while valuing strength in weatherproof outdoor apparel. Does this imply that preference for naturalness is more pronounced in bed linens or baby clothing, and less so in weatherproof apparel? More generally speaking, do consumers prefer naturalness more in durable products for which gentleness is valued and less in durable products for which strength is valued?

Third, this research focuses on one negative expectation that consumers have toward natural products, namely, the belief that naturalness is associated with lower potency or efficacy (Luchs et al., 2010; Pancer et al., 2017). However, prior literature has revealed other negative expectations toward concepts that are related to naturalness. Consumers expect lower functional performance and aesthetic appeal from sustainable products (Acuti et al., 2022; Lindgreen et al., 2009; Luchs and Kumar, 2017) and view organic products as less durable and visually appealing (Vega-Zamora et al., 2014; Zanoli and Naspetti, 2002). Future research should explore further negative expectations that consumers have toward natural products. What negative expectations lead consumers to favor synthetic over natural products? How can marketers effectively counteract these perceptions? Addressing these questions can help reduce consumer hesitancy toward natural products. For example, naturalness is associated with little human intervention (Rozin, 2005), which is generally perceived as desirable. However, in some cases, consumers might prefer human intervention to obtain standardized products. While synthetic products are produced under controlled conditions, natural products are subject to variability in raw material. For example, artificial strawberry flavor is consistent from batch to batch, whereas natural strawberry varies in taste depending on the season (Schwieterman et al., 2014). As a result, consumers might expect natural products to be less standardized compared to synthetic ones. As consumers may prefer consistent flavor across every purchase, variability in taste might be one negative expectation that consumers have toward natural products. Such a negative expectation might lead consumers to prefer synthetic over natural products.

Fourth, our findings suggest that naturalness is less valued in cleaning products, and we recommend that marketers consider avoiding naturalness cues in this product category. However, another avenue for future research is to explore strategies for increasing consumer acceptance of natural cleaning products. Luchs et al. (2010), for example, demonstrated that explicit cues about product strength can attenuate the negative impact of sustainability on product preference. Future studies can investigate how to reassure consumers of the effectiveness of natural cleaning products. Moreover, even if natural cleaning products do offer reduced effectiveness compared to synthetic products, how can marketers still position them as preferable choices?

Fifth, although we categorized products based on three levels of product-body proximity, it may be challenging to assign products to only one of these levels. For instance, washing powder may be classified as a low proximity product, yet it affects clothing that comes into medium proximity to the body. This ambiguity complicates classification. Future research could benefit from refining the product-body proximity construct to allow a more nuanced analysis.

Informed consent was obtained from all survey participants, and all studies were reviewed and approved by the ethics committee of the university.

Note: Respondents were asked to rate all six products in terms of their preference for naturalness. The products on the list were presented in randomized order. The six products were presented on a table in front of the respondents. Apart from the randomly presented products, the survey was identical for all respondents. Terms written in italics were not shown in the questionnaire.

Preference for naturalness

Please indicate, whether you prefer the following products to be synthetic or natural.

(Scale: 1 = Strongly prefer synthetic, 4 = Indifferent and 7 = Strongly prefer natural)

Vitamins

Antibiotics

Hand cream

Hand disinfectant

Surface nourishing oil

Surface disinfectant

Gender

What is your gender?

Age

How old are you? If you prefer not to answer, please type 00.

Level of education

What is your highest level of education that you have completed?

Method

The Replication Study was a 3 (product-body proximity: low vs medium vs high) × 2 (product function: nourishing vs cleaning) within-subject design. In the manipulation of product-body proximity, we distinguished between household care (= low), body care (= medium) and ingestible products (= high). To manipulate product function, we further categorized them into products that primarily aim to nourish and products that primarily aim to clean. We chose the following category descriptions to allow for generalizability while also providing specific product examples. In the low proximity conditions, the categories were described as “household care products that primarily nourish your household items (e.g. surface nourishing oil)” and “household care products that primarily clean your household items (e.g. surface disinfectant).” In the medium proximity conditions, the categories were described as “body care products that primarily nourish your skin (e.g. hand cream)” and “body care products that primarily clean your skin (e.g. hand disinfectant).” In the high proximity conditions, the categories were described as “ingestible products that primarily nourish your body (e.g. vitamins)” and “ingestible products that primarily clean your body (e.g. antibiotics).”

Participants were asked to indicate whether they prefer the six product categories to be synthetic or natural, with 1 = “strongly prefer synthetic” and 7 = “strongly prefer natural” (see Scott et al., 2020). To ensure valid responses, we inserted an attention check that asked participants to “choose the option “indifferent.” From the initial sample of 120 participants recruited via a survey exchange platform, we excluded participants who failed the attention check. The final sample consists of n = 98 participants, of which 72.4% were female, their ages ranged from 18 to 53 years (M = 25.37, SD = 7.24) and 65.3% had at least a bachelor’s degree.

Results

Figure A2 presents the mean preference for naturalness across all six product groups. We conducted a repeated measures analysis of variance to analyze the effect of product-body proximity and product function. The analysis reveals that the preference for naturalness differs across the levels of product-body proximity [F(2,194) = 57.53, p < 0.001]. The mean preference for naturalness is significantly different in the low vs medium proximity conditions (M_low = 4.10, SE = 0.14 vs M_medium = 5.20, SE = 0.13; p < 0.001) and in the medium vs high proximity conditions (M_medium = 5.20, SE = 0.13 vs M_high = 5.54, SE = 0.11; p = 0.003). We further conducted a contrast analysis to test whether the difference in mean preference for naturalness is larger between low and medium proximity than it is between medium and high proximity. That is, we tested whether (M_medium − M_low) > (M_high − M_medium), which can be reformulated into 2 M_medium − M_low − M_high > 0. Thus, we used contrast weights of m_low = −1, m_medium = 2 and m_high = −1. The contrast estimate of C = 0.77 (SE = 0.23) is statistically different from zero [F(1,97) = 11.27, p = 0.001].

Preference for naturalness also differs across product functions [F(1,97) = 49.25, p < 0.001]. In particular, naturalness is more preferred for products that aim to nourish than for products that aim to clean (M_nourish = 5.30, SE = 0.10 vs M_clean = 4.59, SE = 0.13; p < 0.001).

Discussion

The Replication Study reveals the same pattern that we observed in Study 1. First, consumer preference for naturalness increases with higher levels of body proximity (supporting H1). Second, the difference in mean preference for naturalness is larger between low and medium proximity than it is between medium and high proximity (supporting H2). Third, the preference for naturalness is higher for nourishing than for cleaning products (supporting H3). However, compared to Study 1, the contrast in preference for naturalness for nourishing vs cleaning products is less pronounced. One potential explanation is that the stimuli were abstract in the Replication Study, while they were tangible in Study 1. In the latter case, it was presumably easier for respondents to imagine using the product. This may have led to respondents being clearer about for which products they value gentleness/safety (i.e. nourishing products) and for which they value strength/potency (i.e. cleaning products).

Questionnaire used in the Replication Study

Note: The items on preference for naturalness were randomized in order. Terms written in italics were not shown in the questionnaire.

Preference for naturalness

Please indicate, whether you prefer the following product categories to be synthetic or natural.

(Scale: 1 = Strongly prefer synthetic, 2 = Prefer synthetic, 3 = Slightly prefer synthetic, 4 = Indifferent, 5 = Slightly prefer natural, 6 = Prefer natural and 7 = Strongly prefer natural).

Ingestible products that primarily nourish your body (e.g. vitamins).

Ingestible products that primarily clean your body (e.g. antibiotics).

Body care products that primarily nourish your skin (e.g. hand cream).

Body care products that primarily clean your skin (e.g. hand disinfectant).

Household care products that primarily nourish your household items (e.g. surface nourishing oil).

Household care products that primarily clean your household items (e.g. surface disinfectant).

Please choose the option “indifferent”.

Gender

What is your gender?

Age

How old are you? If you prefer not to answer, please type 00.

Level of education

What is your highest level of education that you have completed?

Note: Each respondent was presented with one of the three products: furniture oil, body oil or cooking oil. Here, this product is indicated by the placeholder “[Product].” The matching product image was displayed at the top of the survey. Apart from the randomly presented product, the survey was identical for all respondents. Terms written in italics were not shown in the questionnaire.

Imagine, you want to purchase [Product] for personal use.

Naturalness importance

How important is it to you that [Product] is natural?

(Scale: 1 = Not at all important, 2 = Not important, 3 = Rather not important, 4 = Neither/nor, 5 = Rather important, 6 = Important and 7 = Very important)

Impact on well-being

How much does the use of [Product] impact your well-being? If you do not use [Product], please imagine how much it would impact your well-being.

(Scale: 1 = Very weak impact, 2 = Weak impact, 3 = Rather weak impact, 4 = Neither/nor, 5 = Rather strong impact, 6 = Strong impact and 7 = Very strong impact)

Feeling of contamination

How would you feel when using synthetic [Product]?

(Scale: 7 = Contaminated, 1 = Pure, 7 = Dirty and 1 = Clean)

Attention check

Please indicate to what extent you disagree/agree with the following statement.

(Scale: 1 = Strongly disagree, 2 = Disagree, 3 = Rather disagree, 4 = Neither/nor, 5 = Rather agree, 6 = Agree and 7 = Strongly agree)

Gender

What is your gender?

Age

How old are you? If you prefer not to answer, please type 00.

Level of education

What is your highest level of education that you have completed?