It is known that "Scents can influence people’s attitudes and behavior [...]. The scent of chocolate, for instance, evokes pleasure and arousal for most consumers" (Doucé et al 3). What, then, would happen if a bookshop was filled with a smell of chocolate so subtle that "none of the customers spontaneously noticed the chocolate scent" (7)?
A team of Belgian researchers first "wanted to know to what extent people believe that chocolate corresponds to a certain book genre" (7) and perhaps unsurprisingly discovered "that the two genres most congruent with chocolate scent were Food & Drink (Cook) Books [...] and Romance Novels & Romantic Literature" (7).
Having exposed unsuspecting customers to the chocolate aroma, they found that, "when a chocolate scent was present, customers were 5.93 times more likely to buy congruent books than in the control condition" (11-12) and "compared with the control condition, in the scent condition sales for the congruent genres increased 40.07%, and sales for the incongruent genres increased only 22.19%" (12).
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Doucé, Lieve, Karolien Poels, Wim Janssens, and Charlotte De Backer, 2013. "Smelling the Books: the Effect of Chocolate Scent on Purchase-related Behavior in a Bookstore." Accepted for publication in the Journal of Environmental Psychology. [Abstract]
The image of the chocolate flavour room spray came from Amazon. As far as I know, it was not used in this experiment.