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I've recently learned that scents can trigger memory recall in humans, and am thinking about setting up an experiment where I would attempt to induce memory recall through exposure to scents.

In order to help reduce the amount of experimentation required to actually trigger recall, I'm interested in - What kinds or qualities of scents have been demonstrated to trigger memory recall in humans? Are they pleasant smells/unpleasant, sharp or subtle?

Is there any information about how long of an exposure is needed to trigger such recall? Is it 2 seconds, 15 seconds, an hour?

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From personal experience and also being curious about this phenomenon I can add: Sometimes normally unpleasant smells get "pleasant" by triggering a pleasant experience. And it does work the other way round as well: specific situations can trigger "smell hallucinations" of former similar situations. All in all, this is a very tricky thing to study, so you best start by asking around how it works for different people. For me, it is instant, it does not matter if the smell is pleasant/subtle/..., the memory is more important than the type of smell and a situation also triggers a smell. – skymningen Feb 5 '14 at 9:39

Scents can make memory recalls. We experience this very often, like when we repeatedly smell a good perfume in ,say a shopping mall , and when some person uses it too, we recall the memory of the shopping mall. This hqppens especially when the smell is associated with a very good or very bad incident.

For an experiment, you can expose yourself or someone to a particular smell ,either very good or very bad at any one time, like during examination or holidays for a couple of times. Next when the person again smells the scent he/she will be reminded of the previous exposure.

As regards to how long the exposure is required to trigger recall,it depends upon how strong the smell is (subtle smell takes ponger time) , how good/bad the memory is (very good or very bad memories will be recalled faster) and ofcourse on the memory associativity power of the person.

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up vote 1 down vote accepted

Originally I wanted to try this experiment during sleep, however, the K&R "Principles and practice of sleep medicine" 4th edition, on page 16, under "Olfactory system" mentions that both pleasant (peppermint) and unpleasant (pyridine) smells were poorly recognized during sleep:

  • Both well recognized during stage 1 sleep
  • Peppermint not consciously smelled in stage 2, stage 4 and REM sleep.
  • Pyridine not smelled in Stage 2 sleep
  • Pyridine occasionally smelled in Stage 2 and 4 sleep

It suggests that one conclusion would be that olfactory system of humans is not a good sentinel during sleep.

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