How to design an experiment with scent triggered memory recall in humans?
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.