Showing posts with label confusion. Show all posts
Showing posts with label confusion. Show all posts

Thursday, December 7, 2023

Subjective Olfactory Perception


Two reasons why we aren't good at talking about smells -- 1. we don't share a common percept, and 2.  
we don't share a common language for smells. 

We're genetically coded to perceive smells differently from one another, with a round number at 30% difference across a population. As far as smelling goes, you could say that many of us are mutants. Or you could say there is no "normal" and therefore no mutant. It's just part of the process of evolution. Because of this difference in smell receptors caused by changes in the genes, there are holes in our perception of smells, holes from a societal level, and so the statistics makes it so that the quality of the data, each individual's perception of an odor combined to that of a group of people, is not so good. 

Next, we don't share a common language for smells. Some of this comes from the above problem, but some of it comes from that fact that lots of smells are "social smells" and so the way we talk about them is first and foremost determined by social context, not by some objective characteristic of the smell itself. An example, sort of related, is that we don't talk about the smell of shit in public, it's just not good manners. Or another person's body odor, or the smell of semen, which is almost never ever ever written, not even the word, in general popular literature (in English; maybe this isn't the case in other languages but I don't know).

These two studies below bring some interesting additions to this idea, that the part of our brain that perceives odors is mediated by a pleasure-reward part of our brain, and that language itself comes in two kinds, social and non-social:


Study sheds light on the neural underpinning of subjective odor perceptions
Sep 2023, phys.org

Participants rated 160 odors on 18 perceptual descriptors while under fMRI analysis -- the  orbitofrontal cortex is where the most detailed and subjective percepts reside, and not as much with the amygdala and piriform cortex, regions typically associated with odor processing. 

via Northwestern University, Rhodes College, University of Pennsylvania and NIH National Institute on Drug Abuse: Vivek Sagar et al, High-precision mapping reveals the structure of odor coding in the human brain, Nature Neuroscience (2023). DOI: 10.1038/s41593-023-01414-4


Social vs. language role: Researchers question function of two brain areas
Sep 2023, phys.org

Language just got way more complicated:

"A research team led by Prof. Lin Nan from the Institute of Psychology of the Chinese Academy of Sciences found that during sentence processing, the neural activity of two canonical language areas—the left ventral temporoparietal junction (vTPJ) and the lateral anterior temporal lobe (lATL)—is associated with social-semantic working memory rather than language processing per se."

These regions were sensitive to sentences only if the sentences conveyed social meaning. 

These findings are likely to force a major reconsideration of the functional organization of the cortical language network.

via Institute of Psychology of the Chinese Academy of Sciences: Zhang, G. et al, A social-semantic working-memory account for two canonical language areas, Nature Human Behaviour (2023). DOI: 10.1038/s41562-023-01704-8.

Friday, November 17, 2017

Why You Probably Don’t Know What Musk Really Smells Like


One of the big dogs of the perfume world is also a powerhouse of confusion. What the hell is musk? Do you know? Are you sure?

First, let’s disambiguate the basics. Musky and Musty are not the same thing. Musky is kind of like an animal smell – warm, sexy, intoxicating. Musty is related to moldy, it’s the smell of a dark hamper. Wet and dark, that’s musty. Thing is, body odor can be both musky AND musty, and this is one of the places where the two get intertwined. We can go on and on with this, because there’s this thing I call ‘river musk,’ which is absolutely intoxicating, to me at least, and is the by-product of stuff that lives in the river. Oceans have it too, but it tends to be mixed with dead fish. It’s a secondary metabolite, a kind of seaweed pheromone, which means it’s very similar to animal musk in that it’s a pheromone/chemosignal, but from plants. And yet, it’s related to wet things.

Parenthetically, body odor is actually not musty, for the most part. Usually it’s your dirty clothes that are musty, because they’ve been sitting in a pile on the floor, dark because they’re balled up, and damp because you just took them off, and your body is warm, and the air around you is less warm, so the water vapor in the air condenses on the clothes…either that or you were sweating just before you took them off. Either way, it’s your clothes that smell musty. That being said, we should also note that your armpits can get musty for the same reasons (it’s pretty dark in there). That isn’t what we call body odor, however.

Okay, so we got that out of the way. Sort of. Now for the anosmia part. Anosmia means you can’t smell something. Half the population is anosmic to something, and there are more people anosmic to musk than most other smells. Musk is a really big molecule, one of the biggest we can smell, and for some reason, bigger molecules tend to be invisible to us, but not in the way other anosmias work. It seems to go in-and-out.

Take the behemoth of the synthetic musks, Iso-E Super, which is so super that a perfume was made with only this as its only ingredient (and for non fragrance enthusiasts, that is totally unheard of). Lots of people can’t smell it. Saskia Wilson-Brown of the Institute for Art and Olfaction gave me a sample. I couldn’t smell it. Then I could. Then I couldn’t again. Anyway, because musk has this problem, or because we have this problem with musk, perfumers tend to use lots of musks in their formulas, to make sure that people will be able to smell at least one of the musks in there.

Next problem – the laundry detergent industry. Musks have this attribute where they do really well in fabrics and with detergents. They hold on for a long time (because they’re so big, as a molecule, among other reasons). They’re all over the world of laundry detergents; just about every laundry detergent smells like musk. But you probably don’t know that. You think that smell is the ‘smell of fresh laundry,’ not that of musk. When I tell people this, they don’t believe me, probably because they would rather not associate the smell of sweaty animal bodies with their freshly-laundered sheets. But alas, there it is: the smell of dirty is now the smell of clean.

What’s worse is that these sheets eventually end up in a dark hamper, and smell musty as well as musky. And so now you’re totally screwed.