###### Abstract
The already mentioned Stimulus-Organism-Response (S-O-R) paradigm [1; 7; 22], in which scents generate affective and cognitive responses in consumers (e.g., pleasantness, arousal), which, in turn, affect approach or avoidance behaviors towards products. From an applied perspective, if retailers introduce a positively valenced scent, customers' experience with the store, dwelling time and ultimately purchases will be enhanced;
2. A thematic congruency theory [23; 24; 25] proposing that the effect of scents on behavior depends on their perceived congruency with their target product; in this framework, scents can become a signal or facilitator for drawing attention towards specific products, meaning that when there is a match between the product and the scent, an effect can be expected. It is apparent and should be emphasized that these theories are not mutually exclusive. [PERSON] and [PERSON] [26] explain this with anecdotal example, involving the smell of freshly baked bread, which both gives consumers a pleasant experience (fresh bread smells good), but it also communicates information about the presence and the characteristics of the products, for example, it signals that the bread is fresh and probably still warm. This means that the smell of bread can have consequences for customer behavior in general and for the behavior towards the focal product (bread) and related products (e.g., bakery items). The available literature offers some degree of support for both theories. Several of the available studies reported positive effects of scent applied in a shop on customers' emotional states and on their in-store behavior, measured in terms of dwell time and product choices [27], as well as on stated attitudes such as purchase intention and likelihood to revisit the store [2; 28]. Some studies also suggested that scent may influence the amount of money spent [2], although other studies indicated that this relationship may be more complex. For instance, [PERSON] and collaborators [29] found that a simple scent increased actual spending, whereas a more complex scent had no such effect. Such effects are often moderated by the congruency of the scent with the object, in accordance with the second theory [30]. Nevertheless, several \"null\" results have also been reported (e.g., [26]). This is possibly due to differences in the type of product and environments considered, as well as in variation in methodological aspects--for example, the intensity of the scent and whether it was consciously experienced or not, which is very important because the emotional effects of odors are different depending on whether or not they are consciously perceived [18]. Moreover, according to some (e.g., [31]), in a retail context the ambient scent could have negative effects if they were perceived by consumers as a marketing tool to influence their behavior (at least in absence of elements justifying the presence of that smell). These inconsistencies in the results, however, suggest that the knowledge of the effects of aromachology in retailing is still incomplete. While promising findings have sparked interest in the use of scents in retail environments, much (most) of the available literature is based on studies conducted in controlled settings, such as laboratories or simulated environments (e.g., [30]), and/or is based on attitudinal data such as product and store evaluations (e.g., [32; 33; 34]). It is therefore uncertain how much of these findings correspond to actual behaviors in actual retail environments. Against this backdrop, the present paper presents a systematic review of the literature on aromachology with a focus on customer behavior in actual retail environments. The main research question this review seeks to answer is, therefore, the following: \"what is the evidence for aromachology effects on actual customer behavior in actual retail environments?\" To the best of the authors' knowledge, this is the first review paper to do so in a systematic way.