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Research in, on, or about barking
by Nan Swift, Improbable Research staff
Molnar’s Barking Dogs in Review
“Barking in Family Dogs: An Ethological Approach,” Péter Pongrácz, Csaba Molnár, and Ádám Miklósi, Veterinary Journal, vol. 183, no. 2, February 2010, pp. 141-147. The authors, at Eotvos Loránd University, Budapest, Hungary, report:
Although it is one of the most conspicuous features of dog behaviour, barking has received little attention from ethologists or from an applied perspective. In this review, an ethological look is taken at the communicative aspect of dog barking. Emerging new research has indicated that in the repertoire of dog vocalisations, barking has unique features in showing wide ranges of acoustic parameters, such as frequency, tonality and rhythmicity. Barking has been shown to be context dependent, and provides information for humans about the inner state of the dog although there are few indications that barking is used for intra-species communication. It is assumed that dog barking emerged through selective processes in which human preferences for certain acoustic aspects of the vocalisation may have been paramount. A more experiment-oriented approach is required for the study of dog vocalisation that could shed light on the possible communicative function of these acoustic signals.
Detail from the study “Barking in Family Dogs: An Ethological Approach.”
Molnár’s Method to ID Dogs by Bark Identification (2005)
“Human Listeners Are Able to Classify Dog (Canis familiaris) Barks Recorded in Different Situations,” Péter Pongracz and Csaba Molnár, Adám Miklosi, and Vilmos Csanyi, Journal of Comparative Psychology, 2005, vol. 119, no. 2, 136–144. The authors, at Eötvös Loránd University in Budapest, Hungary, report:
The authors investigated whether human listeners could categorize played-back dog (Canis familiaris) barks recorded in various situations and associate them with emotional ratings. Prerecorded barks of a Hungarian herding dog breed (Mudi) provided the sample. Human listeners were asked to rate emotionality of the vocalization and to categorize the situations on the basis of alternative situations provided on a questionnaire. The authors found almost no effect of previous experience with the given dog breed or of owning a dog. Listeners were able to categorize bark situations high above chance level. Emotionality ratings for particular bark samples correlated with peak and fundamental frequency and interbark intervals. The authors did not find a significant effect of tonality (harmonicto-noise ratio) on either the emotionality rating or situation categorization of the human listeners.
Molnár’s Method to ID Dogs by Bark Identification (2006)
“Can Humans Discriminate Between Dogs on the Base of the Acoustic Parameters of Barks?” Csaba Molnár, Péter Pongrácz, Antal Dóka, and Ádám Miklósi, Behavioural Processes, vol. 73, no. 1, July 2006, pp. 76-83. The authors report:
We tested the often suggested claim that people are able to recognize their dogs by their barks.... Our findings were consistent with the previous studies: human performances did not pass the empirical threshold of reliable discrimination in most cases....
The contexts... affected significantly the listeners’ performances: if the dog barked at a stranger, listeners were able to discriminate the vocalizations better than if they were listening to sounds recorded when the dog was separated from its owner. It is rendered probable that the bark might be a more efficient communication system between humans and dogs for communicating the motivational state of an animal than for discrimination among strange individuals.
Molnár’s Machine-Learning Classification of Dog Barks
“Classification of Dog Barks: A Machine Learning Approach,” Csaba Molnár, Frédéric Kaplan, Pierre Roy, François Pachet, Péter Pongrácz, Antal Dóka, and Ádám Miklósi, Animal Cognition, vol. 11, no. 3, July 2008, pp. 389-400. The authors, at Eötvös Loránd University in Budapest, Hungary, at Ecole Polytechnique Fédérale de Lausanne in Switzerland, and at Sony Computer Science Laboratory in Paris, France, report:
In this study we analyzed the possible contextspecific and individual-specific features of dog barks using a new machine-learning algorithm. A pool containing more than 6,000 barks, which were recorded in six different communicative situations, was used as the sound sample. The algorithm’s task was to learn which acoustic features of the barks, which were recorded in different contexts and from different individuals, could be distinguished from another. The program conducted this task by analyzing barks emitted in previously identified contexts by identified dogs... the efficiency of the algorithm was tested in a classification task in which unknown barks were analyzed. The recognition rates we found were highly above chance level: the algorithm could categorize the barks according to their recorded situation with an efficiency of 43% and with an efficiency of 52% of the barking individuals.
Dog Growling and Perception of Dog Size
“Cross-Modal Perception of Body Size in Domestic Dogs (Canis familiaris),” Anna M. Taylor, David Reby, and Karen McComb, PLoS ONE, vol. 6, no. 2, 2011. The authors, at the University of Sussex, UK, report:
While the perception of size-related acoustic variation in animal vocalisations is well documented, little attention has been given to how this information might be integrated with corresponding visual information. Using a crossmodal design, we tested the ability of domestic dogs to match growls resynthesised to be typical of either a large or a small dog to size-matched models. Subjects looked at the size-matched model significantly more often and for a significantly longer duration than at the incorrect model, showing that they have the ability to relate information about body size from the acoustic domain to the appropriate visual category. Our study suggests that the perceptual and cognitive mechanisms at the basis of size assessment in mammals have a multisensory nature, and calls for further investigations of the multimodal processing of size information across animal species.
Progress in Dog-Bark Silencing
“Sound Attenuation Devices for Dogs Barking (Estimation of Aperture Ratio and Experimental Study of Silencer),” Shuichi Sakamoto, Yuichi Toyoshima, Nobuaki Murayama, Toru Miyairi, Akira Hoshino, and Takatsune Narumi, International Journal of Mechanical Engineering and Applications, vol. 2, no. 1, 2014, pp. 18-24. The authors, at Niigata University, Niigata, Japan, report:
This study is related to the use of natural ventilation silencers for the howling and barking (hereafter referred to as ‘barking’) of dogs....
[We] present the results of silencing by throttle effect using tail-pipe.
‘The Bone is Mine’
“‘The Bone is Mine’: Affective and Referential Aspects of Dog Growls,” Tamás Faragó, Péter Pongrácz, Friederike Range, Zsófia Virányi, and Ádám Miklósia, Animal Behaviour, vol. 79, no. 4, 2010, pp. 917-925. The authors, at Eötvös Loránd University, Hungary; Universität Wien, Austria; and the Konrad Lorenz Institute for Evolution and Cognition, Austria, report:
We provide the first experimental indication that domestic dogs, Canis familiaris, rely on context-dependent signals during interspecific agonistic encounters. We recorded several sequences of growls from dogs in three different contexts: during play, guarding a bone from another dog, and reacting to a threatening stranger. We analysed the acoustic structure of the growls and additionally performed playback tests in a seminatural food-guarding situation. We found that play growls differed acoustically from the other two (agonistic) types of growls, mainly in their fundamental frequencies and formant dispersions. Results of the playback experiment showed that food-guarding growls deterred other dogs from taking away a seemingly unattended bone more effectively than growls recorded in the threatening stranger situation. We ruled out an effect of the signaller’s body weight on the subjects’ responses.
Detail from the study “‘The Bone is Mine’: Affective and Referential Aspects of Dog Growls.”
Some Aspects of Excessive Barking in the Dog
“Assessment and Treatment of Excessive Barking in the Domestic Dog,” Soraya V. Juarbe-Diaz, Veterinary Clinics of North America, vol. 27, no. 3, 1997, pp. 515-32. The author, at Cornell University, includes much advice for dog owners, including this:
A dog’s vocalization sometimes may be difficult to explain. Examples are howling or barking that occurs in response to a particular melody or other auditory stimulus. In addition, any of these vocalizations can be performed as a learned behavior, either taught by the owner, or acquired by the dog secondary to an inadvertently provided reinforcer....
Owners’ opinions concerning the point at which barking becomes problematic are highly variable....
An unintentional mistake on the part of some owners is verbal or physical reassurance of the barking dog, in an attempt to explain, as one would to a fellow human, why the dog need not bark in a particular situation. An explanation to the dog that all is well: “It is only the newspaper being delivered,” for example, spoken in a soothing, soft tone of voice, serves only as a reinforcer.
“Aggressive Behaviour in English Cocker Spaniels and the Personality of Their Owners,” A.L. Podberscek and J.A. Serpell, Veterinary Record, vol. 141, no. 3, July 1997, pp. 73-6. (Thanks to Reto Schneider and Stephen Budiansky for bringing this to our attention.) The authors, who are at University of Cambridge, UK, explain that:
The aim of the study was to determine whether there is an association between the personality of the owners of English cocker spaniels and the expression of aggressive behaviour by their dogs. Two hundred-and-eighty-five owners of purebred English cocker spaniels completed the Catell 16 Personality Questionnaire.... Analyses of the data using unpaired t-tests revealed that the owners of high-aggression dogs were significantly more likely to be tense, emotionally less stable, shy and undisciplined than owners of low-aggression dogs.
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