Ask Alexandra Horowitz

Alexandra Horowitz is a teacher of psychology, animal behavior, and canine cognition at Barnard College, Columbia University, in New York City. She is also author of Being a Dog: Following the Dog Into a World of Smell. Her book is as much about human olfactory cognition as it is about dogs, and her easily accessible narrative offers a heck of a lot of information about the sense we’re all missing.

The book was great, and I am definitely not looking the same at dogs, and their walkers, after reading it. I posted a bunch of notes here. Still, I was compelled to ask her if she might give some time to answer a few questions for the blog here, and what do you know, she found a moment on her summer break to get back to us.  

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AB: 1. The thing I am perhaps most fascinated with when it comes to smell is its ability to tell us things that are otherwise invisible, and at times these things can be very personal information about people.

I have heard from a friend of mine, who is really sensitive to smells, she's an eye doctor, and she says she can tell if one of her patients are cheating on their spouses (still awaiting the details of how the heck she knows that).

Do you find it uncomfortable at times to 'learn' something about someone that you shouldn't know?

AH: I don't know that I have the olfactory acuity of your doctor friend! I have definitely startled my students by knowing who had garlic with yesterday's dinner, or -- not so uncommon -- who's just had a cigarette. I think that they feel uncomfortable with someone having that knowledge, but I don't. Now, if I had a nose with the sensitivity of dogs' noses, maybe I would be gleaning information that I'd rather not have. But one can also simply not sniff....

(I would have to playfully disagree here, as I had to remind myself recently in a somewhat uncomfortable social situation – you can close your eyes, you can put the earbuds in your ears, but you can’t not smell, unless you want to not breathe.)

2. Is there any particular source you recommend for more information on astronauts and smell?

Look at the work that NASA has done to impart flavor to foods. (Also, if you run across an astronaut, ask him! That's what I did...)

(Well I guess I should ask an astronaut because all I get is this - For astronauts, there's little gravity, and this changes the pressure in your head and your sinuses, so that it's hard to breathe through your nose, which means you can't smell - and that means your food doesn't taste like anything. But that's only for the first few days; our bodies get used to it. So why does food continue to taste different? Scientists can't say for sure. For example, it could be that the confined space of the station, crowded with all the other smells of other bodies and machines etc., make a very noisy environment for our noses, and so the food is drowned out. And bland food means more spicy flavors, more Tabasco sauce.) 

3. [This is a reference to Horowitz’ recounting of the trick where a person is asked to choose a book from a shelf, hold it and thumb through the pages, then put it back. The ‘magician’ then enters the room, and recovers the chosen book; “You just smell the books,” Feynman said.] Have you ever pulled the Feynman trick as part of an informal investigation in a public place?

No! Although now that you mention it, I will try it forthwith. I have pulled out le Nez du Vin - small bottles with odors present in wines - with many visitors, and we try to guess the smell source. It's fascinating, as inevitably there will be one person who is surprisingly good at naming the odors, while the rest of us grasp at straws.

(Besides Le Nez du Vin, there's also Le Nez du Cafe, and Le Nez du Whisky. And as I happen to be looking at the World Coffee Research Sensory Lexicon, I see that there are simple ways to make on your own samples - for a papery aroma, boil a coffee filter in water and smell the water; for a 'fermented' note, get some grass and let it ferment in a jar for two weeks. Still, it’s a lot easier to carry a bottle of essential oil in your bag than a jar of fermenting vegetables.)

4. And finally, will we ever have smelling robots?

There are lots of people who are banking on it. DoD and others have funded a lot of research on developing artificial noses -- so far without surpassing a dog nose. In fact, a lot of the fascinating detail I discovered about the airflow in a dog's nose came from a Penn State group that was looking to use that information in the design of an artificial nose.

Still, no one yet knows what combination of factors (in the nose and the brain, in anatomy and behavior) leads to macrosomatic animals being so good at smelling. We will have artificial noses, but they won't soon improve upon the many very good biological ones, I'd predict.

(Artificial noses are usually designed to detect specific odors, like explosives or drugs. So to call them artifical noses needs some explaining. It's like designing an eye that can only see bright green, and then calling it an artificial eye. Not to discredit the work of artificial noses, just disambiguation. If the program she is speaking of here is DARPA's RealNose, it has since been cancelled. There have been plenty of other attempts, and some successful, to make these "single-serving robot noses," but my favorite - remote control bomb sniffing locusts!)

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And so there you have it. Smelling robots are far, far away. About as far as getting a good taylor ham egg and cheese sandwich in outer space.

Much thanks to Alexandra Horowitz for taking the time to give some food for thought, beyond the wealth of information that is already presented in her book.

For more material by Alexandra Horowitz, here’s a talk on NPR, and a video from the University of California TV.

Identifying the Smell-Language Interface

Olfactory Artist Peter De Cupere

Re: Research investigating the physiological basis for odor naming via event-related potentials (ERPs) and fMRI.

The scientists fed subjects cues, either visual or olfactory, followed by words either matching or not matching the cue. A picture of a rose followed by the word “Rose”, the scent of a rose followed by the word “Rose”, or maybe the word “Lemon” instead. What parts of the brain light up when they recognize the match or the mismatch?

The results show that the “cue-modality”, whether it was visual or olfactory, affected different areas of the brain. Performance in recognizing either a match or a mismatch was slower when presented with an olfactory cue versus a visual cue. It was also discovered that the same areas responsible for recognition of an olfactory cue-word match lit up before the word appeared, suggesting less ‘flexibility’ in semantic identification of odors.

Furthermore, when the word is presented for match validation, the cue is reactivated, or re- experienced. But for olfaction, the entire olfactory perception system is not activated, only the parts which had initially coded the sensation semantically. This echoes the assertion that smells cannot be “imagined” in the same way as visual stimuli.

Let's not forget that smell originally functioned as an automatic system with no intervention of cortical processing. Activate - inhibit, that is the way of chemo-sensation. The buck does not cognize the scent of the doe, it reacts. Most of our models or analogies for thinking are visually based. The interface between olfaction and language is akin to the inner mental space in its entirety. The Olfactory-Language Interface, on the other hand, is more like a short cut through this mental space. There is no time for deliberation against the simulated perception, such a thing was impossible or unknown to our organic ancestors.

The chemically-sensitive organism (a redundancy in itself), whether plant or animal, is tied to its environment. The separation between the body and the environment is ultimately what we call this mind space, and it is the thing that makes us human.

(olfactory literature double whammy)

excerpt from The Foul and the Fragrant: Odor and the French Social Imagination, Alain Corbin, 1988; quoted in Sandalwood and Carrion: Smell in Indian Religion and Culture, James McHugh, 2012:

A few simple stereotypes demonstrate the paradoxical nature of the sense of smell. Olfaction as the sense of lust, desire, and impulsiveness is associated with sensuality. Smelling and sniffing are associated with animal behavior. If olfaction were his most important sense, man's linguistic incapacity to describe olfactory sensations would turn him into a creature tied to his environment. Because they are ephemeral, olfactory sensations can never provide a persistent stimulus of thought. Thus the development of the sense of smell seems to be inversely related to the development of intelligence.

Brainless Intelligence

Many-headed slime mold aka Physarum polycephalum, image via the French National Centre for Scientific Research, 2016 

Some folks made slime think. The lowly slime mold, a single-celled protist, shows evidence of learning. It remembers the particular route that avoids irritants placed in its path by tinkering scientists. Yup. Funny thing is, the organism investigated is commonly called the “many-headed slime.” This turns out to be an ironic name, for this organism, without a central nervous system, acts like it does in fact have a head, or a brain, and maybe more than that – many heads, and many brains.

This isn’t the first time slime mold has done amazing feats. It’s used to recreate roadmaps from ancient cultures, or Tokyo’s rail system, just based on topographical information. Who do these single-celled organisms think they are, acting like they have brains? This raises the following question: Where does intelligence come from? Does it need a brain?

In Hidden Scents, while talking about the evolution of the smelling organism, I suggest that the mind is first, and then comes the body. There is something thinking in the most primitive of organisms, deciding which molecules in its surrounding sea of life, and proto-life, should be taken into it, to become part of it, and which molecules should stay outside. To be alive, one of the most basic requirements is to have a boundary between the living thing and the outside. This defines the body. But how does this body, living in a sea of potential bodyparts, determine which parts to keep, and which ones to leave behind. The body comes from somewhere, doesn’t it? And isn’t a body - a living body - more than just a bunch of molecules? If so, what’s organizing those molecules? Who is running the show?

Chemosensation is the basis of this interface, and is the process by which human olfaction works. The initial decision-making algorithms to run with this chemosensation are also the base-algorithms of human thought. Rational thought is a much more complex affair, but at the base is the limbic system, and in smelling we have a model for the kind of thinking performed by a simple, multicellular organism. Or even a collection of single celled organisms, perhaps?

Our current mode for thinking about intelligence is undergoing a major reboot. In light of developments in artificial intelligence, the boundaries of human intelligence are already blurred – many of the things once considered human, rational thought are now programmed into an "artificial life form," i.e., a computer program.

But that’s ok, because current models of the brain follow the schematics of a computer in the same way the nervous system was initially thought of as a closed network of fluids and the brain a pressure-modulator. This was in the age of hydraulics, before we knew what electricity was. Now we know what a computer is, and so the brain is like a computer. Tomorrow, we may know what life is; will we then compare the brain to it?

Our ideas on thinking and intelligence necessitate a brain (whether it’s a computer or a water pump or a lifeform). It's very counter intuitive to hear that things without brains can think. Who knows, next it will be like “Things without bodies can think.” Does the temperature in a room think? Does it have a memory?

Notes:

Intelligent? Brainless slime can 'learn'

May 2016, phys.org

Slime Mold Grows Network Just Like Tokyo Rail System

Laura Sanders, Wired, via Science, 2010

Slime mould builds an ancient road network

Mar 2015, phys.org