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Is there also such a thing as an olfactory illusion?

This question was posed as part of New Scientist’s Last Word series, in which readers give scientific answers to each other’s questions. Here’s what our readers had to say
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There are optical illusions and audio illusions. Is there also such a thing as an olfactory illusion? (continued)

Nicqui Yazdi
Via email

To answer your question – YES, I have this! It’s a weird glitch I have had for many years now. I have a tremendous recall for scents, and certain images, sounds or even just hearing someone talk about something or seeing a picture on television or in a book can trigger smells for me that seem to be incredibly real.

I have literally run around my house in the middle of the night looking for a fire after a news segment on television, or smelled faeces after hearing an advert for chicken manure!

This happens to me quite often, a few times a week probably. It involves all sorts of things, from the smell of bread in a television advert for a bakery to just any old random thing in a book or on a poster. The smell only lasts briefly, mostly just a few seconds, but it is so real.

Certain images, sounds or hearing someone talk about something can trigger smells for me that seem to be very real

Most of the time they are pleasant smells, and it often makes me laugh, especially when I realise that, of course, this is just my incredible ability to recall smells!

I would like to know what this sort of hallucination is called, as I haven’t been able to find anything about it. I once contacted the Oliver Sacks Foundation about it, and Sacks’s personal assistant of more than 30 years just called it my own “olfactory superpower” in her correspondence. I don’t mind at all, but I would love to know if there is an official name for this.

Bruce Denness
Niton, Isle of Wight, UK

Whereas Philip Martin’s random smell illusions are accompanied by recollections of associated places from his past (19 September), mine were always the same smell and accompanying sounds and they occurred in the same place: a previously derelict manor house that I had altered considerably during its restoration. The house had three main floors, but it had a small, single-room, fourth-floor folly, which I used as an office.

The smell illusion began in the office within weeks of our moving in and was always the same: suddenly the sweet smell of Erinmore Mixture pipe tobacco would drift up the stairs to the office, accompanied by the sound of clumping footsteps below. The footsteps never went beyond the third floor – if their owner had been familiar with the previous layout, he may have been confused by my having relocated the fourth-floor staircase.

It is interesting that Martin refers to the brain generating phantom smells. However, mine were often witnessed by others, thereby extending the illusion beyond my own brain.

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Topics: Last Word