Study Suggests Dogs Form Mental Picture Of What They Can Smell


Robin Andrews

Science & Policy Writer

*sniff* benokky1972/Shutterstock

We are driven by expectations, even in the most basic sense of the word. When we hear someone we know talking around a corner, we walk around it anticipating we’ll then see them too. Does the same apply to dogs, though? Do they have a mental image of what they expect to find when they follow a scent trail?

A new paper, published in the Journal of Comparative Psychology, suggests that they do. Although the results are preliminary, they give us a rough insight into the minds of our venerable companions when it comes to their perception of the world around them.


The portion of a dog’s brain dedicated to processing smell is 40 times larger than ours, proportionally speaking, and they’re adorned with 300 million olfactory receptors in their noses. In general, compared to humans, their sense of smell is at least 10,000 times better than ours – so it’s understandable that a dog’s world is driven by smell far more than ours is.

A pair of researchers – from the Max Plank Institute for the Science of Human History and the Friedrich Schiller University of Jena – wanted to know more. “Although it is well known that dogs have an excellent olfactory sense and that they rely on olfaction heavily when exploring the environment or recognizing individuals, it remains unclear whether dogs perceive odors as representing specific objects,” their study explains.

For the purposes of their study, 48 dogs were recruited, almost evenly split between working dogs – those used by the emergency or security services, say – and family dogs. First, two toys that the dogs were particularly keen on were identified, and then the trickery began.

In each trial, a scent path was laid down by one of the toys, and the dogs were encouraged to follow it. Half the time, the dogs found the toy they expected to discover at the end of the road; the other half, the so-called “surprise condition”, featured the second toy.


The idea was that, if the dog had a mental image of the toy they expected to find in their minds, they would act somewhat, well, surprised when they found a different object. If they relied merely on smell and didn’t have said mental picture formed in their mind, then they’d just be content to have followed the trail.

As it turns out, a fair few dogs were indeed surprised. Footage captured them hesitating upon making their discovery, before continuing to search for the toy they presumably expected to find. The effect of the surprise disappeared after a few runs, however – perhaps because they enjoyed being rewarded for playing the game regardless, the team suggest in a press release.

Incidentally, the working dogs were better at the game at first, but the difference between them and the family dogs disappeared over time. All things considered, the authors concluded that a variety of dogs can picture what they can see in their mind, “independent from their educational background.”

More research is of course needed – after all, these conclusions are based more on reasonable inferences than anything more concrete – but this is inarguably a beautifully simple, elegant paper with potentially significant implications for our floofy friends.


  • tag
  • dogs,

  • smell,

  • scent,

  • imagination,

  • trail,

  • mind's eye,

  • mental picture,

  • expectations,

  • follow,

  • [erception