The series on cognition is back! After covering fluffy kittens and their awesomeness, it is now time to grab your tennis balls and prepare yourself for puppies. Now that we already know our companions have well-defined personalities, it is time to call our little packages of excitement and love that we dubbed dogs and head to the yard. These truly amazing fellows can do so many things with so little training that they must be the single most talented animals in the world! - Or so will say all Dog lovers around. - Today we will examine the uniqueness of dogs with some good old science!
Puppies! How can you possibly be mad at this little ball of fluffiness and innocence?
Image Credit: skeeze @ Pixabay
Come on. Besides their friendliness and companionship, dogs are awesome in so many ways that just trying to list it is overwhelming enough to take us more time - and space, physics pun not intended - than we would like. For a start, they are our port of call when it comes to guide animals for the blind and visually impaired;1a dogs can sniff bombs;1b rescue people in snowy places;1c help us with our psychological issues;1d,e improve children's reading skills;1e and much more.
With all these talents, it is almost obvious that dogs are uniquely talented amongst pets. But are they? Remember, scientists didn't take for granted that cats were antisocial and selfish, so why would they assume puppies' are extremely talented? That's right, because science doesn't work that way. So let's delve into some good old research and look at colourful Brain imaging pictures!
We will begin with the basics: pointing. I mean, dog owners know for a fact that their pets are outstandingly good at recognising and following on to gestures. Researchers backed this up, of course. A first formal study back in 1998 already showed that dogs could successfully use gestures as cues to find food.2a Not only that. Dogs participating in that study were so awesome that they retrieved their treats using five different gestures from their owners, i.e., pointing, bowing, nodding, head-turning and glancing at the container covering the tasty treats.2a,b
Additional studies showed the capacity to understand people pointing gestures hinting at a particular place is already present in 9-week old puppies!2c But it goes beyond that: a series of publications claimed dogs were able to correctly identify their owners' gestures even if the latter were brief;2d,e and the effect is independent from distance, so anything from touching the container with hidden food to pointing at it from a distance, or even whilst standing in front of an empty control container, directed the dogs to the right place.2d
And then there is also talking... I mean, come on, all dog owners around are equally guilty of using high pitched voices with their pets. After all, how on Earth would they know who is the good boy/girl of the house? As anybody who ever talked to a dog have probably wondered: "Which brain signalling processes are evolving in my dog's brain to enable human voice recognition? What about comprehension?" - Haven't you ever thought of that?
Well, you are lucky anyway, because scientists did. And so they joined forces with functional Magnetic Resonance Imaging (fMRI for short)3a and let the dogs enter their labs. For those unfamiliar with fMRI,3b this technique is based on machines that apply a very strong magnetic field to watch the blood flowing in the patient's brain in real time. You see, as the neurons in our (and dogs') brains start to fire their electrical signals, they waste more energy to power the whole process. Since animals require oxygen to burn glucose in exchange for energy, fMRI uses the accumulation of oxygenated blood, which causes an increase in measured signal around the active areas of the brain, to watch for patches where the activity is taking place.3a This helps scientist figure out which regions inside the head are firing more frantically during a specific action. Researchers then correlate the highlighted areas with what has already been discovered about the animal's brain using other methods to finally reach a conclusion.
All this marathon - which is just one experiment, mind you - enabled scientists to directly compare how our brains, and those of our beloved dogs, respond to both human speech and dog barks. And... yes, our furry friends' brains seemed to act in a similar way to the grey mass inside our own heads.3c This is quite surprising, since evolutionary biologists estimate the latest common ancestor to canines and primates lived on Earth between 88 and 101 million years ago.4 One could reasonably think that our species would have mutated enough times by now that more changes in our brains would be recorded. But apparently this does not apply to the existence of separate and well-defined areas for sound recognition and interpretation. In fact, species-specific brain areas responsible for speech processing seem to have been pretty well conserved throughout our separate evolutionary adventure.3c
As a result, the brains of our pets fired stronger whenever they were subjected to dogs' barks; whilst human brains were more active during sound processing triggered by people's voices.3c But there is a catch: the emotional content within our voices was relevant in measurements collected from both dogs and us. More specifically, sounds associated with more positive emotions, like pleasure, excitement, and happiness, for instance, caused higher brain activity in both animals than did displeasing utterances associated with negative emotions. It seems, after all, that dogs and humans recognise emotional states contained in speech, and process them altogether with the sound.3c Isn't that amazing? If you want to see the brain imaging pictures, head to the open access original report on Current Biology to check them out.3c
But talking was only one of the interests tackled by scientists with the powerful fMRI technique. Researchers also wondered whether the familiar face recognition that all of us do on a daily basis would show up in dogs as well. I mean, if you ever came home after a long day of work to find your fluffy canine excitingly wagging its tail after just seeing your face, you know exactly why scientists would want to investigate that. And they did.
This time, the dogs were trained to lay still in the fMRI scanner and watch a flat screen showing different pictures in a predetermined sequence. The machine then recorded the active areas inside their brains, and scientists compared the distinct activation patterns that developed while dogs watched pictures of faces, and objects.5 And again, dogs followed suit, - or rather, their brains did - for researchers found areas in the right hemisphere of the brain (temporal cortex) that fired exclusively when watching either human or dog faces.5 Therefore, our fluffy friends do process people's faces in a similar region of their brains devoted to recognising their own fellow canines.
Still, an extra area was consistently showing up during the analysis. When researchers then cleared all the background noise from the data collected in that specific part of the dog brains, they found out it was actually the visual cortex.5 Indeed, dogs devote so much attention to face recognition, and are so attached to humans, that this long standing partnership is hardwired in their brains! But - there is always a but, isn't it? - the authors could not conclude that this effect is exclusive to dogs.5 On that note, if you are willing to train wild wolves to sit in an fMRI and pass through the same series of experiments their evolutionary cousins had endured, by all means let scientists know, and they will be happy to work with you! Yes, you see the problem here. It's very difficult to repeat such experiment with other carnivores, especially the ones that are keen on attacking humans and making us their next meal...
We will begin with the basics: pointing. I mean, dog owners know for a fact that their pets are outstandingly good at recognising and following on to gestures. Researchers backed this up, of course. A first formal study back in 1998 already showed that dogs could successfully use gestures as cues to find food.2a Not only that. Dogs participating in that study were so awesome that they retrieved their treats using five different gestures from their owners, i.e., pointing, bowing, nodding, head-turning and glancing at the container covering the tasty treats.2a,b
Additional studies showed the capacity to understand people pointing gestures hinting at a particular place is already present in 9-week old puppies!2c But it goes beyond that: a series of publications claimed dogs were able to correctly identify their owners' gestures even if the latter were brief;2d,e and the effect is independent from distance, so anything from touching the container with hidden food to pointing at it from a distance, or even whilst standing in front of an empty control container, directed the dogs to the right place.2d
A good boy paying attention to its human giving a command.
Image Credit: dcmx252 @ Pixabay
And then there is also talking... I mean, come on, all dog owners around are equally guilty of using high pitched voices with their pets. After all, how on Earth would they know who is the good boy/girl of the house? As anybody who ever talked to a dog have probably wondered: "Which brain signalling processes are evolving in my dog's brain to enable human voice recognition? What about comprehension?" - Haven't you ever thought of that?
Well, you are lucky anyway, because scientists did. And so they joined forces with functional Magnetic Resonance Imaging (fMRI for short)3a and let the dogs enter their labs. For those unfamiliar with fMRI,3b this technique is based on machines that apply a very strong magnetic field to watch the blood flowing in the patient's brain in real time. You see, as the neurons in our (and dogs') brains start to fire their electrical signals, they waste more energy to power the whole process. Since animals require oxygen to burn glucose in exchange for energy, fMRI uses the accumulation of oxygenated blood, which causes an increase in measured signal around the active areas of the brain, to watch for patches where the activity is taking place.3a This helps scientist figure out which regions inside the head are firing more frantically during a specific action. Researchers then correlate the highlighted areas with what has already been discovered about the animal's brain using other methods to finally reach a conclusion.
All this marathon - which is just one experiment, mind you - enabled scientists to directly compare how our brains, and those of our beloved dogs, respond to both human speech and dog barks. And... yes, our furry friends' brains seemed to act in a similar way to the grey mass inside our own heads.3c This is quite surprising, since evolutionary biologists estimate the latest common ancestor to canines and primates lived on Earth between 88 and 101 million years ago.4 One could reasonably think that our species would have mutated enough times by now that more changes in our brains would be recorded. But apparently this does not apply to the existence of separate and well-defined areas for sound recognition and interpretation. In fact, species-specific brain areas responsible for speech processing seem to have been pretty well conserved throughout our separate evolutionary adventure.3c
As a result, the brains of our pets fired stronger whenever they were subjected to dogs' barks; whilst human brains were more active during sound processing triggered by people's voices.3c But there is a catch: the emotional content within our voices was relevant in measurements collected from both dogs and us. More specifically, sounds associated with more positive emotions, like pleasure, excitement, and happiness, for instance, caused higher brain activity in both animals than did displeasing utterances associated with negative emotions. It seems, after all, that dogs and humans recognise emotional states contained in speech, and process them altogether with the sound.3c Isn't that amazing? If you want to see the brain imaging pictures, head to the open access original report on Current Biology to check them out.3c
A good dog beckoned by its human and ready to play with a funny tennis ball!
Image Credit: Greyerbaby @ Pixabay
But talking was only one of the interests tackled by scientists with the powerful fMRI technique. Researchers also wondered whether the familiar face recognition that all of us do on a daily basis would show up in dogs as well. I mean, if you ever came home after a long day of work to find your fluffy canine excitingly wagging its tail after just seeing your face, you know exactly why scientists would want to investigate that. And they did.
This time, the dogs were trained to lay still in the fMRI scanner and watch a flat screen showing different pictures in a predetermined sequence. The machine then recorded the active areas inside their brains, and scientists compared the distinct activation patterns that developed while dogs watched pictures of faces, and objects.5 And again, dogs followed suit, - or rather, their brains did - for researchers found areas in the right hemisphere of the brain (temporal cortex) that fired exclusively when watching either human or dog faces.5 Therefore, our fluffy friends do process people's faces in a similar region of their brains devoted to recognising their own fellow canines.
Still, an extra area was consistently showing up during the analysis. When researchers then cleared all the background noise from the data collected in that specific part of the dog brains, they found out it was actually the visual cortex.5 Indeed, dogs devote so much attention to face recognition, and are so attached to humans, that this long standing partnership is hardwired in their brains! But - there is always a but, isn't it? - the authors could not conclude that this effect is exclusive to dogs.5 On that note, if you are willing to train wild wolves to sit in an fMRI and pass through the same series of experiments their evolutionary cousins had endured, by all means let scientists know, and they will be happy to work with you! Yes, you see the problem here. It's very difficult to repeat such experiment with other carnivores, especially the ones that are keen on attacking humans and making us their next meal...
Brains! Or at least their representation in the fMRI.5
Highlighted areas indicate the places where increase in brain activity was recorded. Arbitrary colour coding was added to differentiate amongst six dogs. Upper section (yellow background) correspond to 'dog facial areas'; lower section (purple background) correspond to the visual cortex. Labels 'R' and 'L' respectively indicate the right and left hemispheres.
Image Credit: Dilks et al., PeerJ 2005, 3, e1115 (see reference 5).
© 2015 Dilks et al. This picture is provided under the CC-BY-4.0 license. See footnote 6 for a full disclaimer of the modifications applied to the original image.
With all these traits, and even evolutionary imprints in their brains, we can only assume dogs are uniquely talented, can't we? Well, not so fast! Yes, compared to what we recently reviewed in terms of cat cognition, it is fair to say we know a lot more about dogs. However, you must acknowledge the domestication of dogs happened way before cats decided to domesticate themselves!7a - It's no joke, scientists did conclude there are no clear signs that we were responsible for the domestication of kittens. Instead, they might just have come along our barns and silos to hunt rats and plagues that were eating our food.7a,b
More to the point, researchers consider the wild wolf (Canis lupus) to be the ancestor to our domestic dogs (Canis familiaris).7c The former seemed to have joined forces with humans around 14,000 years ago, at least that is when the earlier fossils can be found in Central Europe.7c Domestic cats (Felis catus), on the other hand, only begin to appear in the fossil record around 6,000 years ago in areas around Mesopotamia and Egypt.7a,b - Bastet,8 is that you? - Therefore, we had double the time to domesticate and train our dogs to become obedient pets, whilst cats... Well, kittens will be kittens and continue to ignore us forevermore, or at least until we finally get to grips with our cat domestication agenda.
But back to the uniqueness argument. It seems that we like to praise "humans' best friend" far more than we should do. At least in terms of the available scientific evidence. For instance, we showed the remarkable capacity dogs have to recognise and respond to our pointing signals... Well, it turns out the list of animals that can do similar things is extensive,9a and includes bats,9b chimpanzees,9c dolphins,9d elephants,9e goats,9f horses,9g jackdaws,9h parrots,9i ravens,9j seals,9k wolves2c and cats!2e
Then, there were claims that our big puppies are highly talented in judging our attention states.9a,10a But further investigations including better experimental design and control conditions failed to replicate the original results.10b - Oh, don't even get me started on the whole 'replication crisis' in science. This is a matter for an entire future piece in the blog...
Finally, researchers reported dogs were uniquely able to imitate one another, and were even clever enough to choose when to do so.9a,11a Once again, scientists performing more careful examinations didn't find the same effect. In fact, a more elaborate experimental setup, which included control conditions specifically created to test the original hypothesis, failed to replicate the findings.11b But this topic is still not settled; at present we just don't know whether dogs are really good at imitating other dogs or not.9a - At least scientifically, because we all have seen those cute videos with mamma dog teaching her puppy to go down a scary ladder!11c
Well, we sure learnt a lot about how our fluffy dogs and cute puppies behave, and how their brains are hardwired to interact with us. But there is still a long way ahead for future discoveries. Let me remind you that we don't even know what 'conscience' truly is, let alone deciding on how (un)conscious actions affect the firings and connections inside the brains of our fellow canines. The science of cognition has a lot to gain by joining forces with fMRI, but science will eventually catch up, don't worry.
The last piece I want to leave you with is a reminder. And no one could have ever phrased it better12a than the late astrophysicist and highly skilled science communicator Prof. Carl Sagan.12a,b When he popularised an 18th century Enlightenment tenet defined by the renowned Scottish writer David Hume,12a,c everybody followed suit, and here I do the same:
But back to the uniqueness argument. It seems that we like to praise "humans' best friend" far more than we should do. At least in terms of the available scientific evidence. For instance, we showed the remarkable capacity dogs have to recognise and respond to our pointing signals... Well, it turns out the list of animals that can do similar things is extensive,9a and includes bats,9b chimpanzees,9c dolphins,9d elephants,9e goats,9f horses,9g jackdaws,9h parrots,9i ravens,9j seals,9k wolves2c and cats!2e
Dogs and cats and nearly all animals we test understand pointing!
Image Credit: Gellinger @ Pixabay
Then, there were claims that our big puppies are highly talented in judging our attention states.9a,10a But further investigations including better experimental design and control conditions failed to replicate the original results.10b - Oh, don't even get me started on the whole 'replication crisis' in science. This is a matter for an entire future piece in the blog...
Finally, researchers reported dogs were uniquely able to imitate one another, and were even clever enough to choose when to do so.9a,11a Once again, scientists performing more careful examinations didn't find the same effect. In fact, a more elaborate experimental setup, which included control conditions specifically created to test the original hypothesis, failed to replicate the findings.11b But this topic is still not settled; at present we just don't know whether dogs are really good at imitating other dogs or not.9a - At least scientifically, because we all have seen those cute videos with mamma dog teaching her puppy to go down a scary ladder!11c
Well, we sure learnt a lot about how our fluffy dogs and cute puppies behave, and how their brains are hardwired to interact with us. But there is still a long way ahead for future discoveries. Let me remind you that we don't even know what 'conscience' truly is, let alone deciding on how (un)conscious actions affect the firings and connections inside the brains of our fellow canines. The science of cognition has a lot to gain by joining forces with fMRI, but science will eventually catch up, don't worry.
The last piece I want to leave you with is a reminder. And no one could have ever phrased it better12a than the late astrophysicist and highly skilled science communicator Prof. Carl Sagan.12a,b When he popularised an 18th century Enlightenment tenet defined by the renowned Scottish writer David Hume,12a,c everybody followed suit, and here I do the same:
Extraordinary claims require extraordinary evidence.
Carl Sagan, 1979
Science Extras:
Do you want to know more about fMRI? I am listing below some good sources that I hope will help, even if you don't have a strong knowledge in this area.
• Introductory Texts little scientific background required
The basics of fMRI and its medical applications is covered by the researchers at the National Institute of Biomedical Imaging and Bioengineering (NBIB). Head to their website and check their resources.13a
Abi Berger, science editor of the BMJ, offers an overview of how the technique works from a more biophysical perspective. Check this open access article and quench your curiosity.13b
• Advanced Texts science jargon heavy
You can check this open access review on the bits and bobs of the fMRI technique, its different flavours and implications related to their clinical applications.13c
Do you want a more biomedical and diagnostic-oriented perspective? Good for you, because neurologists Dr Stéphanie Debette and Prof. Hugh Markus got your back covered!13d
Additional Resources:
Are you interested in exploring the question of jealousy in dogs from a scientific and behavioural lens? Fret no more, for you can check this open access paper in the Journal Animal Sentience to read more about the topic.13e
Are you into science, but your forte is the dog memes? Well, if you remember the good folks of the Cheezburger network, they also have plenty of resources on dogs.13f
Are you a proud dog owner? Did you realise how intelligent and people-oriented these wonderful fluffy balls of joy are?
Let us know in the comments down below.
_______________1a) Audrestch, H. M.; Whelan, C. T.; Crice, D.; Asher, L.; England, G. C.; Freeman, S. L., Disabil. Health. J. 2015, 8, 469; b) Levine, J., The Education of a Bomb Dog, Smithsonian.com, https://www.smithsonianmag.com/innovation/the-education-of-a-bomb-dog-4945104/, published 07/2013, retrieved 24/04/2019; c) Blumberg, J., A Brief History of the St. Bernard Rescue Dog, Smithsonian.com, https://www.smithsonianmag.com/travel/a-brief-history-of-the-st-bernard-rescue-dog-13787665/, published 01/03/2016, retrieved 24/04/2019; d) Wells, D. L., Brit. J. Health. Psych. 2007, 12, 145; e) Jalongo, M. R.; Astorino, T.; Bomboy, N., Early Childhood Educ. J. 2004, 32, 9.
2 a) Miklösi, Á.; Polgárdi, R.; Topál, J.; Csányi, V., Anim. Cogn. 1998, 1, 113; b) Udell, M. A. R.; Giglio, R. F.; Wynne, C. D. L., J. Comp. Psychol. 2008, 122, 84; c) Gácsi, M.; Győri, B.; Virányi, Z.; Kubinyi, E.; Range, F.; Belényi, B.; Miklósi, Á., PLoS One, 2009, 4, e6584; d) Miklósi, Á.; Soproni, K., Anim. Cogn. 2006, 9, 81; e) Miklósi, Á.; Pongrácz, P.; Lakatos, G.; Topál, J.; Csányi, V., J. Comp. Psychol. 2005, 119, 179;
3 a) Thompkins, A. M.; Deshpande, G.; Waggoner, P.; Katz, J. S., Comp. Cogn. Behav. Rev. 2016, 11, 63; b) Center for Functional MRI, What is FMRI?, University of California, San Diego, https://cfmriweb.ucsd.edu/Research/whatisfmri.html, retrieved 27/04/2019; c) Andics, A.; Gácsi, M.; Faragó, T.; Kis, A.; Miklósi, Á., Curr. Biol. 2017, 24, 574.
4 Springer, M. S.; Murphy, W. J.; Eizirik, E.; O'Brien, S. J., Proc. Nat. Acad. Sci. 2003, 100, 1056.
5 Dilks, D. D.; Cook, P.; Weiller, S. K.; Berns, H. P.; Spivak, M.; Berns, G. S., PeerJ 2005, 3, e1115.
6 The original picture, which represents Figure 2 in reference 5, had its black background and labels removed. Then, highlighted areas in yellow and purple were superimposed to the fMRI scans, with further addition of visual elements to connect the upper and bottom text boxes to the coloured frames introduced in the previous step. Labels 'R' and 'L' were finally added, and represent the same regions attributed as 'right-' and 'left hemispheres' in the authors' original interpretation.5 No further modifications were introduced.
7 a) Turner, D. C., "The human-cat relationship" in: The Domestic Cat: The Biology of its Behaviour, Cambridge: Cambridge University Press, 2nd ed., 2000, pp.193-206.; b) Bradshaw, J. W. S.; Goodwin, D.; Legrand-Defrétin, V.; Nott, H. M. R., Comp. Biochem. Physiol. 1996, 114A, 205; c) Clutton-Brock, J., "Origins of the dog: domestication and early history" in: Serpell, J. (ed.), The domestic dog: its evolution, behaviour, and interactions with people, Cambridge: Cambridge University Press, 1st ed., 1995, pp.7-20.
8 The Editors of Encyclopædia Britannica, "Bastet", Encyclopædia Britannica 2019, https://www.britannica.com/topic/Bastet, published 01/03/2019, retrieved 26/04/2019.
9 a) Wynne, C. D. L., Curr. Dir. Psychol. Sci. 2016, 25, 345; b) Hall, N. J.; Udell, M. A. R.; Dorey, N. R.; Walsh, A. L.; Wynne, C. D. L., J. Comp. Psychol. 2011, 125, 341; c) Tomasello, M.; Call, J., Anim. Cogn. 2004, 7, 213; d) Pack, A. A.; Herman, L. M., J. Comp. Psychol. 2004, 118, 160; e) Smet, A. F.; Byrne, R. W., Curr. Biol. 2013, 23, 2033; f) Kaminski, J.; Riedel, J.; Call, J.; Tomasello, M., Anim. Behav. 2005, 69, 11; g) Dorey, N. R.; Conover, A. M.; Udell, M. A. R., J. Comp. Psychol. 2014, 128, 337; h) von Bayern, A. M.; Emery, N. J., Curr. Biol. 2009, 19, 602; i) Giret, N.; Miklósi, Á.; Kreutzer, M.; Bovet, D., Anim. Cogn. 2009, 12, 1; j) Schloegl. C.; Kotrschal, K.; Bugnyar, T., Behav. Process. 2008, 77, 61; k) Scheumann, M.; Call, J., Anim. Cogn. 2004, 7, 224.
10a) Gácsi, M.; Miklósi, Á,; Varga, O.; Topál, J.; Csányi, V., Anim. Cogn. 2004, 7, 144; b) Udell, M. A. R.; Dorey, N. R.; Wynne, C. D. L., Learn Behav. 2011, 39, 289.
11 a) Range, F.; Virányi, Z.; Huber, L, Curr. Biol. 2007, 17, 868; b) Kaminski, J.; Nitzschner, M.; Wobber, V.; Tennie, C.; Bräuer, J.; Call, J., Tomasello, M., Anim. Behav. 2011, 81, 195; c) The Dodo, Patient Dog Teaches Puppy How To Get Down Stairs, YouTube, https://www.youtube.com/watch?v=J9pDAbpga_g, published 18/07/2016, retrieved 27/04/2016.
12 a) Deming, D., Philosophia 2016, 44, 1319; b) Wikipedia: The Free Encyclopedia, Carl Sagan, Wikipedia.com, https://en.wikipedia.org/wiki/Carl_Sagan, retrieved 27/04/2016; c) Wikipedia: The Free Encyclopedia, David Hume, Wikipedia.com, https://en.wikipedia.org/wiki/David_Hume, retrieved 27/04/2019.
13 a) National Institute of Biomedical Imaging and Bioengineering, Magnetic Resonance Imaging (MRI), National Institute of Health (USA), https://www.nibib.nih.gov/science-education/science-topics/magnetic-resonance-imaging-mri, retrieved 27/04/2019; b) Berger, A., BMJ 2002, 324, 35; c) Hennig, J.; Speck, O.; Koch, M. A.; Weiller, C., J. Magn. Reson. Imaging 2003, 18, 1; d) Debette, S.; Markus, H. S., BMJ 2010, 341, c3666; e) Cook, P.; Prichard, A.; Spivak, M.; Berns, G. S., Animal Sentience 2018, 3, 117; f) Cheezburger, Inc., I Has a Hotdog - Funny Dog Pictures, Cheezburger.com, https://icanhas.cheezburger.com/dogs, retrieved 27/04/2019.
2 a) Miklösi, Á.; Polgárdi, R.; Topál, J.; Csányi, V., Anim. Cogn. 1998, 1, 113; b) Udell, M. A. R.; Giglio, R. F.; Wynne, C. D. L., J. Comp. Psychol. 2008, 122, 84; c) Gácsi, M.; Győri, B.; Virányi, Z.; Kubinyi, E.; Range, F.; Belényi, B.; Miklósi, Á., PLoS One, 2009, 4, e6584; d) Miklósi, Á.; Soproni, K., Anim. Cogn. 2006, 9, 81; e) Miklósi, Á.; Pongrácz, P.; Lakatos, G.; Topál, J.; Csányi, V., J. Comp. Psychol. 2005, 119, 179;
3 a) Thompkins, A. M.; Deshpande, G.; Waggoner, P.; Katz, J. S., Comp. Cogn. Behav. Rev. 2016, 11, 63; b) Center for Functional MRI, What is FMRI?, University of California, San Diego, https://cfmriweb.ucsd.edu/Research/whatisfmri.html, retrieved 27/04/2019; c) Andics, A.; Gácsi, M.; Faragó, T.; Kis, A.; Miklósi, Á., Curr. Biol. 2017, 24, 574.
4 Springer, M. S.; Murphy, W. J.; Eizirik, E.; O'Brien, S. J., Proc. Nat. Acad. Sci. 2003, 100, 1056.
5 Dilks, D. D.; Cook, P.; Weiller, S. K.; Berns, H. P.; Spivak, M.; Berns, G. S., PeerJ 2005, 3, e1115.
6 The original picture, which represents Figure 2 in reference 5, had its black background and labels removed. Then, highlighted areas in yellow and purple were superimposed to the fMRI scans, with further addition of visual elements to connect the upper and bottom text boxes to the coloured frames introduced in the previous step. Labels 'R' and 'L' were finally added, and represent the same regions attributed as 'right-' and 'left hemispheres' in the authors' original interpretation.5 No further modifications were introduced.
7 a) Turner, D. C., "The human-cat relationship" in: The Domestic Cat: The Biology of its Behaviour, Cambridge: Cambridge University Press, 2nd ed., 2000, pp.193-206.; b) Bradshaw, J. W. S.; Goodwin, D.; Legrand-Defrétin, V.; Nott, H. M. R., Comp. Biochem. Physiol. 1996, 114A, 205; c) Clutton-Brock, J., "Origins of the dog: domestication and early history" in: Serpell, J. (ed.), The domestic dog: its evolution, behaviour, and interactions with people, Cambridge: Cambridge University Press, 1st ed., 1995, pp.7-20.
8 The Editors of Encyclopædia Britannica, "Bastet", Encyclopædia Britannica 2019, https://www.britannica.com/topic/Bastet, published 01/03/2019, retrieved 26/04/2019.
9 a) Wynne, C. D. L., Curr. Dir. Psychol. Sci. 2016, 25, 345; b) Hall, N. J.; Udell, M. A. R.; Dorey, N. R.; Walsh, A. L.; Wynne, C. D. L., J. Comp. Psychol. 2011, 125, 341; c) Tomasello, M.; Call, J., Anim. Cogn. 2004, 7, 213; d) Pack, A. A.; Herman, L. M., J. Comp. Psychol. 2004, 118, 160; e) Smet, A. F.; Byrne, R. W., Curr. Biol. 2013, 23, 2033; f) Kaminski, J.; Riedel, J.; Call, J.; Tomasello, M., Anim. Behav. 2005, 69, 11; g) Dorey, N. R.; Conover, A. M.; Udell, M. A. R., J. Comp. Psychol. 2014, 128, 337; h) von Bayern, A. M.; Emery, N. J., Curr. Biol. 2009, 19, 602; i) Giret, N.; Miklósi, Á.; Kreutzer, M.; Bovet, D., Anim. Cogn. 2009, 12, 1; j) Schloegl. C.; Kotrschal, K.; Bugnyar, T., Behav. Process. 2008, 77, 61; k) Scheumann, M.; Call, J., Anim. Cogn. 2004, 7, 224.
10a) Gácsi, M.; Miklósi, Á,; Varga, O.; Topál, J.; Csányi, V., Anim. Cogn. 2004, 7, 144; b) Udell, M. A. R.; Dorey, N. R.; Wynne, C. D. L., Learn Behav. 2011, 39, 289.
11 a) Range, F.; Virányi, Z.; Huber, L, Curr. Biol. 2007, 17, 868; b) Kaminski, J.; Nitzschner, M.; Wobber, V.; Tennie, C.; Bräuer, J.; Call, J., Tomasello, M., Anim. Behav. 2011, 81, 195; c) The Dodo, Patient Dog Teaches Puppy How To Get Down Stairs, YouTube, https://www.youtube.com/watch?v=J9pDAbpga_g, published 18/07/2016, retrieved 27/04/2016.
12 a) Deming, D., Philosophia 2016, 44, 1319; b) Wikipedia: The Free Encyclopedia, Carl Sagan, Wikipedia.com, https://en.wikipedia.org/wiki/Carl_Sagan, retrieved 27/04/2016; c) Wikipedia: The Free Encyclopedia, David Hume, Wikipedia.com, https://en.wikipedia.org/wiki/David_Hume, retrieved 27/04/2019.
13 a) National Institute of Biomedical Imaging and Bioengineering, Magnetic Resonance Imaging (MRI), National Institute of Health (USA), https://www.nibib.nih.gov/science-education/science-topics/magnetic-resonance-imaging-mri, retrieved 27/04/2019; b) Berger, A., BMJ 2002, 324, 35; c) Hennig, J.; Speck, O.; Koch, M. A.; Weiller, C., J. Magn. Reson. Imaging 2003, 18, 1; d) Debette, S.; Markus, H. S., BMJ 2010, 341, c3666; e) Cook, P.; Prichard, A.; Spivak, M.; Berns, G. S., Animal Sentience 2018, 3, 117; f) Cheezburger, Inc., I Has a Hotdog - Funny Dog Pictures, Cheezburger.com, https://icanhas.cheezburger.com/dogs, retrieved 27/04/2019.
