Thursday, October 21, 2021

Nobody Is an Expert at Everyday Smells, Not Even the Smell Experts

If you find the language of smell interesting, Asifa Majid is the scientist to follow. This is a study from 2016, but it never hurts to be reminded that your ability to perform overt olfactory exploration on your environment is likely way worse than it could be. 

We don't talk about smells, and that's part of the reason why we can't identify them. A forgotten milk box in a student's locker over summer vacation may just as well be a poor rodent who happened to die under your staff refrigerator. These are pretty different smells, but they're both "bad," and that's about as much as we need to know. (They're both protein-based, so those two descriptions are not too far apart.)

Now you might think that a wine expert would be an ideal model for a chemosensing humanoid, but no. Experts are only good at smelling the things they've been trained to smell. They are only good at smelling what they already have words for. Granted, they have lots more words than your average person, but only words for odorants specific to their discipline.
Experts only have a limited, domain-specific advantage when communicating about smells and flavors:
Neither expert group was any more accurate at identifying everyday smells or tastes. Interestingly, both wine and coffee experts tended to use more source-based terms (e.g., vanilla) in descriptions of their own area of expertise whereas novices tended to use more evaluative terms (e.g., nice).
-Not All Flavor Expertise Is Equal: The Language of Wine and Coffee Experts. Ilja Croijmans, Asifa Majid. June 2016,  PLoS ONE 11(6): e0155845.
Putting things in perspective, it should be noted that a master perfumer has a vocabulary of **thousands** of words for smells, which is ten times more than the wine or coffee expert. (You want to know some of the words are in the smell lexicon for coffee experts? Check out the World Coffee Research Sensory Lexicon and scroll down to "Publications;" and then you can compare that to the 1,000+ descriptors in the Sigma Aldrich catalog of fragrance chemicals which are purchased by perfumers to make perfume.)

If you want to be an "Everyday Smell Expert" all you have to do is start to come up with a vocabulary of your own for the smells around you, and then start paying attention. Soon you'll be able to recognize odors in your environment at really low thresholds, and maybe even be able to accurately  associate them with their source. 

Post Script:
Later in the paper, the idea of cultural difference as inhibiting our olfactory prowess:
"The difficulty people have in naming smells and flavors could be a WEIRD (Western, Educated, Industrialized, Rich, Democratic) affair. -source

So another approach to becoming a better everyday-smeller would be to try growing up in a non-WEIRD country.

Thursday, October 14, 2021

Neuromorphic Odor Translator Helps Robots Express Their Feelings

Neural network trained to properly name organic molecules
Aug 2021,

Do you ever have a problem naming that smell? It's not just you. Science has this problem too, but maybe not for long. 

Smells are volatile organic compounds that have evaporated and entered your nose. Although they almost always occur in combination with others and not in isolation, us humans want to reduce smells to their individual components, and then name them. After all, in order to think about something, you have to know it's name. (Is that true?) 

The problem is that organic molecules are big, with lots of chemicals joined together in lots of ways, so coming up with a naming convention for all these permutations is hard. IUPAC, the International Union of Pure and Applied Chemistry, sets the convention for naming molecules. And boy is it complicated.

Take sugar, a common molecule known to us by its simple name "sucrose;" in IUPAC, it's called (2R,3R,4S,5S,6R)-2-[(2S,3S,4S, 5R)-3,4-dihydroxy-2,5-bis(hydroxymethyl)oxolan-2-yl]oxy-6-(hydroxymethyl)oxane-3,4,5-triol.

Since we do live in the computer age, folks want to automate this naming process for when they discover new molecules. But as you can imagine by looking at the IUPAC name for sucrose, the algorithm at the core of that naming convention is really hard to write. So they decided to use a neural network instead.*

*I'm casually calling a neural network "neuromorphic," but in the past few years, real neuromorphic computers have forced a distinction here that I'm ignoring here for the sake of a more clickable title. 

This new artificially intelligent chemical translator is not a magical structure-to-name translator that can just look at a chemical and give it a name; that's still out of reach. It does, however, translate between IUPAC and another naming convention called SMILES.

Trained on PubChem's 100 million molecules, this translator ultimately shows how the utility of the new approach of using neural networks to help us write algorithms from the bottom up instead of the top down, which really is a revolution in computing. 

And if you think it would be cool to have robots that can smell, or to ensure that future humans maintain their sense of smell as they evolve into hyperdimensional algorithms, then making odors machine-readable is how you do that.

via Skolkovo Institute of Science and Technology, Lomonosov Moscow State University and start-up Syntelly: Lev Krasnov et al, Transformer-based artificial neural networks for the conversion between chemical notations, Scientific Reports (2021). DOI: 10.1038/s41598-021-94082-y

Thursday, October 7, 2021

On Olfactory Navigation

I purposely read this book Supernavigators (2019) hoping to get some snippets on using our sense of smell to find things, and I wasn't disappointed. 

Humans were led to a random location within a room diffused with two odors. After brief sampling and spatial disorientation, they had to return to this location. Humans located the target with higher accuracy in the olfaction-only condition than in the control condition and showed higher accuracy than chance. 
-Jacobs, L.F.; Arter, J.; Cook, A.; and Sulloway, FJ. (2015). "Olfactory orientation and navigation in humans," PLOS 'One, 10(6), e0129387.

Note there are two different versions of olfactory navigation -- one where you track an odor to its source (this relies heavily on bilateral input, aka stereo-olfaction) and the other, much more common for modern-day humans, is when you identify a place by its odor. We usually have our eyes open, and being the ocularcentric creatures that we are, we are likely to use visual cues and not even realize the odor-identity of a place. 

But it doesn't stop here, the rabbit hole continues, and this one goes all the way back to the golden days of behavioral science, when rats told us everything we wanted to know about ourselves: 
This report is ultimately based on rat experiments, with the "men" part being only conjecture by the researcher; and he concedes, "My argument will be brief, cavalier, and dogmatic. For I am not myself a clinician or a social psychologist. What I am going to say must be considered, therefore, simply as in the nature of a rat psychologist's ratiocinations offered free.
*Ratiocinations are another word for thoughts that also happens to remind the reader that we're talking about rats (he italicized the rat in ratiocinations).

The "mapmaking" happens during what they call "Vicarious Trial and Error" or "VTE'" and described as "the hesitating, looking-back-and-forth, sort of behavior which rats can often be observed to indulge in at a choice-point before actually going one way or the other." If you're not a scientist, you can probably just call it "thinking."

via Berkeley Labs: Tolman, E.C. (1948). "Cognitive maps in rats and men," Psychological Review, 55(4), p.189.
And with that, let us not forget that olfaction is the first sense. Before all the other ways we sense our environment, bacteria and fungi were using chemotaxis, detecting and navigating their way through a world of chemical gradients. The essay at the end of Hidden Scents, called "Olfactory Space and n-Dimensionality" tells the story of the primordial eukaryote as it chemo-taxis its way through evolution, past the multi-cellular organism, the chordata (animals with vertebrate), and eventually to the big-brained, smooth-skinned monkeys that we are today.

The neocortex is an outgrowth of the nose-brain, and not the other way around, and therefore olfaction can be a useful model for understanding the n-dimensional information network in which our brains operate. The world is typically understood as a 3-dimensional space, but in fact, from the perspective of the brain, we are navigating and interacting with an infinitely-dimensional information space.