The power of odour preference – divine or disgusting?

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Do you have an odour preference? A favourite aroma? The faintest whiff of which scent prompts a smile every time? What is it that brings you such pleasure – the scent or the memory that it elicits? Smell is thought to be one of the most powerful senses when it comes to memory. In an instant your unconscious will suddenly bring to mind a memory so strong that it can literally stop you in it’s tracks. 

Coming up . . .

The power of smell

As a young customs officer boarding my first ship was an unexpectedly emotional experience. Not that I shared my feelings with my colleagues. I was a professional officer in HM Customs. A grown up with an important job. I was also 19 years old. A mere babe. The sudden rush of memory hit me as if I’d just hit the button for warp speed and it caught me on the hop. As I stepped onto the deck, the smell of engine oil hit my olfactory bulb and I was transported to the deck of an oil tanker. The sun was hot and I could see my dad smiling at me as I skipped past the coiled ropes and white metal fences that bordered the path to his arms.

As a child I’d been lucky enough to travel with my merchant sailer father. Whenever we could, my mum would pack us up and we’d travel to various ports around the world to meet up with whichever oil tanker he was serving on. And then we’d sail a section of the trip before heading home again without him. And all this came rushing back to me because I got a whiff of engine oil. 

Indelible odours

I still love that smell. Whenever I get the chance to head up to Scotland to island hop, I feel great affinity and a sense of being home as I drive onto the ferry. Large or small, I think all boats, ships, ferries must have that smell. Even when I searched the luxury liner QE2, the smell of the oil was still present. And never more so that in the engine room. 

Lots of my time as a dog handler was spent in ships’ engine rooms. My drug detector dog Ash loved to search there. On paper from the dog’s perspective, this is very far from being the ideal search area. Often so noisy that you can’t hear your own voice. Hot, steamy, sweaty. The metal floors constantly vibrate as the engines power the vessel. But he loved it down there. He’d bound up the steep open metal stairs, working from the bottom level to the top with joy and vigour. It’s no wonder that I was skinny and fit as I worked in these oily saunas with him. 

Favourites?

I have no idea what he thought about the scents in those engine rooms. Of course he was overjoyed when he found his target scents. But as for his opinion on the other scents, I can’t say. My current dogs make it very clear which scents they really enjoy. Most of them are linked to food or to other animals. Both categories are innately important. But this doesn’t mean that they don’t have favourites. 

Ettie loves meat and meaty products. She will locate the cupboard where you keep your bully beef chews faster than Boris Johnson can tell a lie. Cherry loves bread. Drooling will start almost as soon as I take the garlic bread / naan bread / pizza out of the oven. And Ella loves cheese. All cheese. Of course they’re associating the smells with eating, but that doesn’t mean that they don’t have favourites. For example, I’ve never had a dog come running into the kitchen because I’m cooking mushrooms. But crack open a can of tuna and hey presto, I’ve got three dogs in front of me. 

Unexpected preference

But there are fragrance preferences that are less simple to explain. My munsterlander Solo adored the scent of flowers. He’d shove his face into any vase or bouquet of flowers he could reach. And he was happy to mooch around gardens inhaling the scent from as many blooms as possible. When he died I planted a rose called Velvet Fragrance in his honour. It has a deep, strong scent that I know he would have loved. 

We can learn to love scent that wouldn’t naturally be on our list of favourites. Like engine oil. When I first started teaching scentwork I worked with a few different target scents. I chose the ones that I could see were being used most frequently. One of those was aniseed or anise. To my surprise, many of the dogs who were introduced to it actively recoiled from it. (I’ve only had this reaction from one dog to the scent of catnip. We chose a different target scent for him.) Such was their obvious displeasure that I quickly dropped it from my target scent options. It surprised me because I’d never read or heard of anyone reporting that their dog didn’t like it. It is still commonly used in scentwork and even in scentwork competitions. But still I can’t recall anyone else talking about dogs not liking it.

Target scents – does preference matter?

This prompted me to ponder a few questions. 

1. Are handlers/trainers not recognising that some dogs dislike it?
2. If they do recognise it do they put their own desires above the dogs’ preferences and teach the dog that the unpleasant scent is worth finding because the rewards are high?
3. Does the high value reward teach the dog to like the previously disliked scent? Or to tolerate it as a means to an end? 

I don’t have the answers. And TBH, I’m not prepared to test them out. It’s not fair to put the dog through something she doesn’t like just so that I can have my questions answered. The stakes are just not high enough to warrant that. I’m not sure the answers are out there in terms of academic studies. I’m aware of studies that show how scent can be used to enhance welfare. But I’ve not seen any that show a definite preference to particular neutral scents, i.e. ones with which the dog has no previous association. 

Scent association

There have been studies on human preferences to odours. And more often than not the scents are associated with emotions. Change the emotion, you change the preference. The response to a smell that was associated with a bad experience can be changed. As can the way that odour is described. 

In a study by Herz and von Clef (2001)* they introduced test participants to 5 different odours. Each was described in two ways. For example, a pine scent was described as ‘christmas tree’ and also as ‘disinfectant’. And iso-valeric + butyric acid was alternately called ‘vomit’ or ‘parmesan cheese’. The test subjects’ response to the actual scents were found to correspond to the negative or positive connotations of the words used to describe them. So strong were these responses that participants couldn’t believe that they’d been smelling the same scent each time. (You can find out more in this interesting paper produced by the Sense of Smell Institute)

Odour

I’ve been careful with my vocabulary choices in this blog. Us scentworkers think of the word odour as a neutral description. But for non-scentworkers, the word odour is more often connected with ‘bad’ or ‘unpleasant’. Fragrant is generally positive, while smell is frequently negative. 

Our dog’s perceptions

Of course, how we describe scent has no effect on how our dog’s perceive it. Nor do our preferences correspond to what our dogs like or dislike. While the smell of vomit makes most of us want to run a mile, our dogs will usually be running in the opposite direction! But we can observe the dog’s body language and act accordingly. When teaching scentwork for pleasure as we do, there is no need to change the dog’s association with a scent. Better to introduce a neutral scent, and associate that with great experiences and rewards. So I’d never ‘work a dog through’ her dislike of lemon scent. Knowing that many dogs dislike citrus scents, I’d avoid them and select a more appropriate target odour such as catnip. (For more info on scent choice check out this previous blog post)

What smells does your dog love?

So what about your dog – what are her favourite odours? And I wonder if you have any favourite smells? Maybe ones that you love but other people hate? Please share in the comments below.

*Herz, R.S., & von Clef, J. (2001). The influence of verbal labeling on the perception of odors: Evidence for olfactory illusions? Perception, 30, 381-391