The Effect of Stimulating and Soothing Smells on Heart Rate and Memory

This study was performed to investigate the effect of smell on heart rate and short-term memory. Lemon and lavender were used as stimulating and soothing scents respectively, in order to determine if these odors increased or decreased heart rate and correspondingly improved or impaired memory. Sixty-seven participants from California State University, Sacramento were divided into three groups to test the hypothesis that the stimulating scent of lemon would enhance memory and increase heart rate, whereas lavender would reduce memory and decrease heart rate. However, the results from this study were not statistically significant to support this claim. Our olfactory sense is unlike any other sensory modality. It is the only sense that is directly connected to the environment, has neurons that continuously regenerate throughout life, and has neuron axons that are unmyelinated. Having “unmyelinated axons” means that neurons’ axons are not surrounded by protective cells called “glial cells.” Glial cells make up myelin, which is a protective layer of cells around the cell axon that allows for fast transmission of information from one neuron to the next. Not being myelinated causes the sensory signal from the environment to the olfactory bulbs (the structure that perceives smells) to move slower, which is why there is a delay in our responses to smell, and why smells linger in our noses after the scent in the air has passed. The olfactory system contains structures that are also components of the limbic system, the center that is in charge of emotion and sensory processing. Among these structures is the amygdala, which is involved with emotional processing, specifically fear; and the hypothalamus, which maintains homeostasis within the body; and the hippocampus, which is involved in forming new long-term memories. The olfactory system’s close location to the limbic system explains why certain smells bring back such strong, vivid, emotional memories. The first time we come in contact with a special smell