Rachel S. Herz, an assistant professor of psychology at Brown University, provides the following explanation:
The simple answer is yes, but the reasons may not be what you expect. Odors do affect people¿s mood, work performance and behavior in a variety of ways but it isn¿t because odors work on us like a drug, instead we work on them through our experiences with them. That is, in order for an odor to elicit any sort of response in you, you have to first learn to associate it with some event. This explanation for how odors affect us is based on what is known as associative learning, the process by which one event or item comes to be linked to another because of an individual¿s past experiences. The linked event is then able to elicit a conditioned response for the original situation. In olfaction, the process can be understood as follows: a novel odor is experienced in the context of an unconditioned stimulus, such as surgical procedure in a hospital, which elicits an unconditioned emotional response, such as anxiety. The odor then becomes a conditioned stimulus for that hospital experience and acquires the ability to elicit the conditioned response of anxiety when encountered in the future. This mechanism explains both how odors come to be liked or disliked, as well as how they can elicit emotions and moods.
We know that the neurological substrates of olfaction are especially geared for associative learning and emotional processing. The olfactory bulbs are part of the limbic system and directly connect with limbic structures that process emotion (the amygdala) and associative learning (the hippocampus). No other sensory system has this type of intimate link with the neural areas of emotion and associative learning, therefore there is a strong neurological basis for why odors trigger emotional connections.
Both studies with children and cross-cultural research provide strong evidence that responses to odors are learned via associative mechanisms. A number of studies have shown that odor learning begins before birth, when flavor compounds from the maternal diet get incorporated into amniotic fluid and are ingested by the developing fetus. In studies where mothers¿ consumption for distinctive smelling substances such as garlic, alcohol or cigarette smoke were monitored during pregnancy, it was found that their infants preferred these smells compared to infants who had not been exposed to these scents. These early learned preferences also influence food and flavor preferences in later childhood and even adulthood. [Note that flavor is produced primarily by odor; taste contributes only the sensations of salt, sour, sweet, bitter and savory.] Feeding, in addition to providing nutrition, is an opportunity for close physical contact and emotional bonding between mother and child. Thus, the role of emotion is clearly evident in associative learning in a food context. Other examples where infants experience cuddling in conjunction with incidental odors like perfume have shown that these incidental scents then become better liked.
Although the majority of odor responses are acquired during childhood, because of the novelty and salience of so many experiences, any time a new smell is encountered associative learning mechanisms can determine odor perception. Anecdotes of liking or disliking scents because of their connection to significant others and idiosyncratic cuisine preferences are typical examples of how associative learning and emotional context influences odor perception. Important in this regard are cross-cultural findings that clearly show that one¿s man¿s meat is another man¿s poison
In the mid-60¿s in Britain, adult respondents were asked to rate a battery of common odors. A similar study was conducted in the United States in the late 1970¿s. Included in both was the smell of wintergreen, which was given one of the lowest pleasantness ratings in the British study. In the US study, in contrast, it received the highest pleasantness rating. History can explain this difference. In Britain, the smell of wintergreen is associated with medicine and, particularly for the participants in the 1966 study, with analgesics that were popular during WWII (a time that these individuals would not remember fondly). Conversely, in the US, the smell of wintergreen is exclusively a candy mint smell and one that has very positive connotations. There is also no empirical cross-cultural data that indicates any consensus for odor evaluations to ¿offensive¿ scents. Indeed, in a recent study undertaken by the US military to create a "stink bomb," it was impossible to find an odor (including US army issue latrine scent) that was unanimously considered unpleasant across various ethnic groups. So it isn¿t just ¿neutral¿ or moderate odors that vary by culture, what we think ¿stinks¿ does too.