Did you know that approximately 2 million people in the United States have no sense of smell? Lack of smell is a disorder known as anosmia, and can be caused by damage to the nerves that transmit information from your nose to your brain. Our sense of smell serves an important purpose, we use it to distinguish between edible and inedible items in our lives, including fresh or rotten foods, and even particular toxins that have strong, unpleasant smells. In this activity you will test the scent perception of your volunteers, and learn about how smell is closely associated with memory.
This activity is not appropriate for use as a science fair project. Good science fair projects have a stronger focus on controlling variables, taking accurate measurements, and analyzing data. To find a science fair project that is just right for you, browse our library of over 1,200 Science Fair Project Ideas or use the Topic Selection Wizard to get a personalized project recommendation.
Your sense of smell is also known as olfaction. Olfaction takes place when molecules known as oderants bind to specific receptors in your nasal cavity inside your nose. When activated, these receptors transmit information along sensory nerves to the olfactory bulb, a neural structure at the base of your brain that transmits smell information from your nose to deeper brain structures. Many of these deeper structures are involved in scent processing as well as memory and emotion, and as a result, our scent memories tend to be highly associative, and strongly linked with memories. Interestingly, many of the areas that receive scent information are particularly old, in terms of brain development, and existed before the cortical areas that give us consciousness. Thus, it is often more difficult to consciously identify and label a smell, instead we associate scents with the memories and emotions that they evoke.
In this activity you will be testing scent memories in your volunteers, and learning about how we remember and recall scents!
Note: Feel free to use different extracts or essential oils if you have them available. Follow the instructions below, replacing the unused scents with those you choose to use.
Extra: Try this activity with another volunteer, but this time split the bags into two groups. Have them guess the first 5 scents with no reference list, and the second 5 scents with a list. Which one was easier for your volunteer?
Extra: Try mixing two smells together and see which are easier and more difficult for your volunteers to identify.
Observations and Results
In this activity you should have found that your volunteers had a much easier time identifying the same smells when they had a reference list to use. In this first trial, when the volunteer tried to guess the smells without knowing the possible choices, they may have written down less descriptive guesses, such as ‘candy’ or ‘cookies’ or ‘candle’. However, when you gave them a list to use as a reference, your volunteer had a much easier time correctly identifying the scents in each bag.
Your olfactory system transmits information directly or indirectly to brain areas of the limbic system associated with memory and emotion, including the amygdala, hypothalamus, olfactory cortex and hippocampus. As a result, we often have difficulty labeling scents by their name, instead we identify them by their associated memories. You might smell the scent of cinnamon and name it as ‘Christmas’ or ‘Holidays’, since it’s common to associate the scent of cinnamon with this time of year.
Because scent memories are associative, and thus somewhat difficult to label correctly, your volunteer probably had fewer correct answers in the first column of their table. However, once you gave them the reference sheet you provided more context for each of the scents they experienced. It was much easier for your volunteer to match the scent with the correct label than it was for them to identify the scents without a reference list.
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Megan Arnett, PhD, Science Buddies
Science Buddies |
Sensation, perception, scent, olfaction, memory, learning
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