Making Sense of Smell

How does smelling work?

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  • Outside stimuli is attracted into the outer part of the nose.
  • The stimuli (tiny particles that travel through air) travel up the nose to cilia (hair-like structures at the top of the nasal passages. The cilia are like taste buds and change every few weeks and can sense over 1,000 different smells.
  • There is 10 million receptor sites on the cilia that process the stimuli send into to the brain.
  • The smell is processed in the olfactory bulbs right beneath the frontal lobe. The thalamus sends information to other parts of the brain.
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Basic Smell Principles of Sensory Transduction

Sensory transduction is the process of changing stimuli into neural activity.

  • Absolute threshold is the lowest amount of stimulation that can be detected. For example, a drop of perfume in a three room apartment.
  • Difference threshold is the smallest difference between two stimuli.
  • Sensory adaption is when a stimuli becomes less noticeable the longer it happens for.
  • If a neighborhood smells like oil because of the oil refinery down the street, a resident would get used to it.


  • A smell can affect behavior; if someone sniffs then more of the molecule making the scent is getting information to the brain. If a scent is bad it can cause a person to be more keen on getting away from it. For example a skunk hit by a car make cause the people in the surrounding area to not go outside. If a bakery just bakes fresh bread, then the passerby may walk into the bakery.
  • Sense of smell allows a perception of the world that can help a person live in an environment. If someone smells gasoline in a house, then they may want to leave because of a gas leak.


  • Olfaction- the sensation of smell
  • Process of smelling-particles traveling through the nose to the cilia to receptor cites to the olfactory bulbs to the brain.
  • Olfactory bulbs-areas of the brain locate just above the sinus cavity and just below the frontal lobes that receive information from the olfactory receptor cells.
  • Anosmics/hyposmia- hyposmia is a reduced ability to smell and detect odors. Anosmics is when no odors can be detected.
  • Pheromones- chemicals that are secreted in our sweat and other bodily fluids that are believed to influence the behavior of the opposite sex, such as triggering sexual interest and excitement.
  • Nasal cavity-large air space above and behind the nose in the middle of the face.
  • Aromatherapy-practice of using natural oils to enhance psychological and physical well-being.

  • Effect of smell on emotions- how something smells or how someone smells can affect our perception of that thing or person. For example the smell of fresh baked bread can result in a person wanting bread. Also women often are more attracted to men who smell good.

And now for the experiment...

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