Olfactory Phantoms and Illustrations of the Dynamics of Perception

The other day I got an interesting incoming link. Something I wrote was selected to be part of a hypothetical college curriculum. It is on a curriculum sharing website but I don’t think anyone is actually using it yet. Students in a sensory science class get to learn about illusion in the various senses and because there is not a lot written about olfactory illusion I was selected probably by default (default! woohoo!). I covered another phenomenon years ago I called the maraschino blackberry illusion where texture (haptic heft) dramatically changed the threshold of perception of an aroma. I think some bar programs are finally getting around to using it. I did it again in a beautiful context with fernet (and kirschwasser) aromatized cherries and I’m doing it yet again using the reflux de-aeration technique (to preserve the lemon juice) to perfectly place a sidecar inside a golden raspberry. The aroma and color were leached out of the golden raspberry so I’m basically just using its perfect body of cells as a vehicle to harness the influence of haptic heft on aroma.

We are slowly getting to the punchline but we need to cover a few more strange phenomenons.

Whoever selected the paper for the curriculum was interested in the “illusion” where wormwood hand sanitizers I made were used to train someone (myself) on an aroma. I found with the unique training I experienced similar aromas in certain wines (I found two wines: Cos Cerasuolo and an Anjou blanc) that were bizarrely amplified; like 10X amplification. Sometimes the same phenomenon exists with the aroma of dead mice and those in the pest control business that inadvertently end up with unique olfactory training can notice the aroma in a room when no one else can.

Wine pairings are part illusory and reading Gordon M. Sheperd’s Neurogastronomy confirmed some of my suspicions about wine and food interaction that I covered in an incomplete post called: contrast enhancement (in space and time) for food & wine interaction. The idea didn’t exactly catch on but I am right so I guess I’ll just give people a few more years to adopt it (mach bands! & nutritional preference comparisons!).

Now for the punchline: I’m setting out to explore how many of the aromas we “perceive” under certain circumstances are to varying degrees actually phantoms.  They are induced by incoming sensory stimulus (or by words which are symbols) but they are ultimately just recollections.  This is different than just making loose comparisons of incoming stimlui to known things, in what I’m describing you eventually generate whatever percentage of the known thing that doesn’t exist in the incoming stimuli.

Maybe we can start with the simplest olfactory phantom I’ve been able to generate and then build some background around it. To make the champagne bottle manifold I started a small plastic foundry. To develop the skills I needed to make the manifold part I started making reproductions of 19th century door knobs; giant lion heads and rococo stuff.  Some I cast in a translucent red plastic to generate some Joris Karl Huysmans style artifice and decadence. Anyhow, I had to drill this red plastic. Well, every time I did, I started to smell cherries. After a while I knew I was going to and I still did. The black plastic smelled of licorice.

Compounds called phthalates in the plastic have an aroma that notoriously converges with gustatory-sweetness. This form of sweetness coupled with the color is enough to trigger a phantom aroma and illustrate some of the dynamics of perception.

Perception is a tricky thing because all sorts of facets seamlessly join together. In the past I’ve talked obsessively about the sensory and symbolic world being glued together by the theory of cognitive dissonance and becoming the mechanism by which we acquire acquired tastes.  Perception involves the meeting of sensory inputs with recollections.  Improperly using recollections to complete incoming experience is the basis of many optical illusions.  So perception is going to be (by varying degrees) divided by fresh incoming sensory experiences and a sort of filling in the blanks via recollection. Most of the time recollection will correctly fill in the missing pieces.  Incentives exist to use completion to save resources.  Apparently it is more efficient than processing everything from scratch. Olfaction being the sense most closely tied to memory and thought to be particularly resource intensive might be subject to more completion by recollection than any other sense, though I’m only speculating (this whole post is a giant speculation).

As the distribution of perception slides around we may be subject to more or less illusory completion.  I’ve seen sensory science researchers hint at this distribution by outlining different perception strategies such as an active or a passive strategy.  An active strategy may tip the scales to processing new sensory data while a passive strategy may tip the scales towards completion by recollection.

The distribution could then be subject to other influences such as reward mechanisms.  Certain degrees of salt in our food, such as on a tomato, lowers the threshold of perception of an aroma.  The co-experience of the aroma and and salt may etch themselves in our mind so we can use those aromas to predict the presence of salt in the future, salt being something we need.  Sugar under certain circumstances has a similar effect, often referred to as “flavor enhancement”, that can lower the threshold of perception of an aroma.  Our rewards systems might jostle the distribution of perception any which way.  The sweetness in the plastic did not make me pay attention to an actual incoming aroma sensation but rather created one based on the influence of the color.  In my red plastic example the cherry aroma was more or less 100% generated by recollection but in many other cases aroma fragments that are being sense are being added to.

Many spirits researchers talk about pattern recognition or gestalts being important to distillates.  The famous spirits consultant Dr. Jim Swan has mentioned that when coming up with a new scotch whiskey blend it needs to have enough elements to be recognizable as a scotch whiskey (a gestalt) but then enough to set it apart.  The other big time spirits guru John R. Piggot in his amazing paper “Origins of Flavour in Whiskies and a Revised Flavour Wheel: a Review” starts by saying “Improved congener analyses have not yielded greater understanding of whisky flavour: a dynamic interaction between individuals and flavour components.”  The dynamic interaction mentioned by Piggot is another way of acknowledging the distribution of perception.  He then goes on to mention holistic patterns and gestalts as part of perceiving flavor. In memory, the cherry is a gestalt of sweetness and color, and aroma.  When only two of the three are present recollection may complete the third.

Piggot’s paper gets very dense in the chemistry but his introduction is very accessible and pretty amazing. He demonstrates an astounding understanding of neuroscience to go along with his second to none understanding of every reaction that generates every congener in every step of the whisky making process.  Piggot notes the interaction of the sensory and symbolic world but doesn’t exactly use the words I’ve adopted so it is probably best to quote him. According to Piggot, “In consumers, causality interactions (slaving effects) exist between perceptual and sensation levels, dictated by cues (Fig. 1): the human mind influences the brain.”  There is something vague about saying “the human mind influences the brain” but I’d like to think it parallels my language.  I do not agree with the way he uses the term “perception” because I think you can stumble into “which taste do you mean” territory.  When he says “perception” I think it could be better named “recollection” and perception instead is the sliding summation of incoming sensation and recollection. Sensory scientists have needed to get away from the term “taste” for flavor perception and maybe the same needs to be done to deconstruct perception and consciousness.

Robert Léauté in his 1989 James Guymon lecture very vaguely mentions fatty acid esters being “fixitives” for other aroma compounds.  His idea of a fixative might relate to the building of overlapping incomplete gestalts that recollection might complete in beautiful ways but we’ll touch upon that in a bit.

I should probably mention that infamous incident were a group of wine experts were served room temp white wine dyed red and nearly all were fooled into thinking they were drinking a proper red wine.  They described the aromas of the wine using object comparisons attributed to red wines and not whites. Well they were drinking a red-wine and if a degree of the distinct things we think we smell are phantoms, they were perceiving everything exactly as they should.  Their advanced library of recollections may have even made them more vulnerable than an amateur taster.

Another known phenomenon in wine trickery is simply tasting a wine after being baited with an aroma suggestion.  The suggested aromas can appear vividly.  I do not think this is widely studied or acknowledged because no one wants to be the victim of it.  We feel as though it shouldn’t happen so we never submit to curiosity and explore experiencing it.  A aroma suggestion isn’t a sensory input like gustatory-acidity or tannin. It starts that way but becomes a symbol or stand in for a value that triggers recollection. Some symbols thrown around in wine-speak, like goose berry, are not good bait because for many people the word is not a stand in for any recollection. To this day I’ve still never eaten a goose berry.

Robert Parker, who is famous for his wild tasting notes, might perceive the world with some unique distribution abnormally skewed towards recollection almost like a form of mild autism.  The gestalts he encounters make him hallucinate wildly. Every wine Parker encounters, which remains incomplete to the rest of us, he can complete apparently with great pleasure.  This might be a bit of a stretch because the language used by wine critics has no real responsibility to describing the wine. They just have to use harmonic language and typically more extraordinary language for more extraordinary and rare sensory values.  If we accept the fact that wine makes Parker hallucinate, to be honest I’d like to join him and learn his technique because illusion or not, it seems like fun.

To get back to spirits, most whiskey’s are colored with caramel to converge with their aromas.  Accepting that it is important to the quality of our hallucinations we should probably thank and recognize producers that do a good job of it.  An award could be given at the San Francisco spirits festival like “best dye job”.  I used to scoff at coloring but now I’m warming up to it.

A realm I had fun exploring the influence of color was with amaretto.  Everyone knows the darkly colored Disaronno brand and other darkly colored generics but I was really taken by a Portuguese almond (benzaldehyde) liqueur where the color was interpreted as a much lighter raw almond shade.  I was so taken by it I re-distilled my own version and left it uncolored so the aroma would diverge from the crystal clarity.  The results were captivating.  There was a dramatic divergence from expectation.  The crystal clarity and the light it captured made the aroma glow but it was just the Portuguese version re-distilled, re-cut, and re-sugared.  Benzaldehyde based liqueurs are so easy to distill the real artistry probably comes in when coloring them.

In cocktails we may sometimes experience perception dominated by recollection.  Many cocktails that are simultaneously tart and bitter come across as distinctly grapefruity though there is no grapefruit in them.  True these drinks, which often feature citrus juice, have a few aroma compounds in common with grapefruit, but the loose gestalt is enough to trigger a very distinct association even when the chemicals and all there various ratios do not remotely line up.

Now to go back to Robert Léauté, the idea of partially illusory aromas might explain the importance of very generic aroma compounds like ethyl acetate and acetaldehyde in spirits.  In large quantities these compounds are considered flaws, but sub threshold Léauté describes them as his “fixatives”.  Because these compounds are so abundant in fruits they may be an integral part of gestalts. Ethyl acetate could function like the sweet smelling phthalates found in the plastic and when coupled with one other sensation like a color we would have enough to hallucinate marasca cherries like Robert Parker.

Léauté, who is a master cognac distiller, explains that ethyl acetate and acetaldehyde, should be kept under the threshold of perception but distillates should be cut to get as close to that line as possible.  It might make sense in this case to rename the “threshold of perception” to “threshold of attention”.  We seem to be able to perceive astoundingly small quantities of things.  Our own nose is more sensitive than any analytic tool we’ve been able to build.  According to Gordon M. Sheperd our nose can differentiate aroma compounds by one carbon atom.  So maybe something is not detectable to our attentional spotlight but it is somehow still detectable enough that it can interact with other components synergistically and influence pattern recognition.  D.W. Clutton’s paper from 1978, The Flavour Constituents of Gin finds all sorts of compounds in gin that are sub threshold yet they are somehow very important to defining the character of the product.  Thresholds of perception may work very differently than is commonly thought.

Recollection may have some strange bearing on wine pairings.  In some pairings when food and wine “match” an aroma from the food can be reflected back into focus.  I had thought previously that a change in contrast detection was experienced and likened the phenomenon to the black art theater of the magician Omar Pasha.  An alternate explanation could possibly be that with the next experience (which is the wine after the food) a similar pattern confuses the mind and triggers recollection of the food.  Many of these types of pairings happen when the perceived acidity of the food and the wine match.

I don’t want to leave people thinking that everything we smell is an illusion.  We obviously need intense libraries of recollection to generate phantoms from.  It is probably safe to say that we mostly always are actively smelling when we think we are, but where is the dividing line and small details are we adding in to what were are really smelling? And if alcoholic beverages like wine and spirits remind us of so many things as seen in so many tasting notes, could they be the hub of olfactory illusion?

Do some people not taste wine well because they have no language to fragment and parse the experience or because they have no library of recollections to generate the illusions?