## 3 Results and Analysis
### Reported Effects on Customers' Behaviors and Theoretical Accounts  
Consistent with the expectations, the vast majority of studies built on the S-O-R and the the mathic congruency theory to explain the effect of scents on behavior often considered both frameworks within the same study. For instance, [PERSON] et al. [44] studies the effect of adding a chocolate scent on general store behavior (such as length of stay, interaction with the staff, etc.) in a bookstore, which would reflect the S-O-R view, but also the effect on sales for thematically congruent items (cookbooks and romantic novels), which would reflect the thematic congruency theory. Generally, support for the S-O-R theory seems to be found in the literature at least when it comes to attitudinal outcomes: accordingly, almost all studies included in this review report a positive effect of adding a pleasant scent on, e.g., engagement with the store, satisfaction with the experience, intention to revisit, etc. However, evidence of an effect on actual customer behavior is not always straightforward. For example, [PERSON] [1] found that addition of a pleasant scent made the in-store environment more engaging, but with no differences in actual behavior between scented and control conditions. More to the point, studies that employed two qualitatively different but equally valenced scents reported that only one out of the two actually affected customer behavior, meaning that valence/pleasantness in and of itself is not enough to produce the expected effect on customers' behaviors. For example, [PERSON] [39] reported that only one of two scents introduced in a Las Vegas casino increased the amount gambled on slot machines, whereas results for a second scent were not different from the control (no odor) conditions. Similarly, [PERSON] [24] in a bookstore study found that addition of in-store browsing and sales figures were slightly higher for a congruent scent (coffee) than for an incongruent scent (rose) of equal valence. Finally, [PERSON] et al. [27] investigated the effect of adding warm vs. cool scents (equally pleasant) to an optics stores, and found that shoppers were more likely to purchase premium brands and to purchase more items in the warm scent condition. Overall, the literature evidences that valence (pleasantness) is a necessary but not sufficient condition for the effectiveness of scents to affect customer behavior. This could suggest that other perceptual characteristics of the scents, such as congruency with the product category, are more important in terms of affecting customer behavior. Yet, support for the thematic congruency hypothesis is also limited, with studies reporting mixed results. Perhaps the best support for this theory is in the study on clothing by [PERSON] and collaborators [37], which found a positive impact of adding a \"masculine\" or \"feminine\" scent on sales of, respectively, men's and women's clothing items. [PERSON] et al. [44] found that adding a chocolate scent to a bookstore increased buying behavior towards thematically congruents books, but only when controlling for gender (the addition of the scent worked for women but not for men). [PERSON] and [PERSON] [26] investigated whether the degree of thematic congruency between an ambient odor and a magazine affected magazine sales in bookstores by using two odors (a grass odor, congruent with soccer, animal/nature and gardening magazines, and a sunflower odor, congruent with personal care and women's magazines), but found that the ambient scent did not increase sales for thematically congruent magazines, nor did it decrease sales for incongruent magazines. Similarly, [PERSON] and collaborators [1] reported no differences in product-related behavior (e.g., dwelling time) in a different electrical retailer store when a congruent scent was present (vs. a control condition).