Are you curious whether your dog completely understands what you say? The answer is in a study by Brazilian researchers, published online in the journal PLoS-ONE.
Dr. Daniela Ramos and Prof. Cesar Ades, both of the University of São Paulo (USP), have successfully demonstrated that the domestic dog (Canis familiaris) is able to perform a behavior on a command composed of two words: one referring to an object and the other to an action to be performed relative to the object.
Previous studies have confirmed the processing of action-object sentences in animals such as chimpanzees, sea lions, dolphins and parrots. Dogs’ responsiveness to a simple command when they are required either to perform an action (“sit”, “roll”) or to react selectively to one of several objects (“fetch the ball, the teddy etc.”) has been studied many times, while an in-depth analysis of two-item comprehension in canines has never been performed.
For their experiments, the researchers involved a female mongrel dog named Sofia. She was raised as a pet by a member of the research group and lived with him throughout the study.
“A mongrel dog was chosen as it would best represent domestic dogs in general,” Dr. Ramos explained in the interview with Sci-News.com. “The same result from a particular breed would maybe represent a special ability restricted to that breed only.”
A team of trainers conducted appropriate training and testing sessions for Sofia up to three times a day and three to six times a week in a dedicated room at the USP’s Institute of Psychology. These procedures were carried out during 22 months and Sofia was two years old when the experiments ended.
“The study was designed to investigate whether a dog would be able to understand simple sentences composed of an object followed by an action command,” Dr. Ramos said. “Owners commonly say their dogs can do it but we know sometimes dogs in fact react to sentences as if they were “single” commands (e.g. “go out”, “go fetch toy”) or systematically respond to part of the sentence deducting from the context what is the behavior to be performed.”
After basic training, Sofia was trained to approach one of several objects (ball, key, bottle and stick) the name of which was presented as part of a sentence and to point or fetch familiar but unnamed objects (e.g. a plastic toothbrush). All commands were voiced in Portuguese.
In the object training, she was rewarded for correctly approaching only two of the four objects set (ball and key). During the action training sessions, Sofia had to fetch or point to the familiar but unnamed object presented singly in a transparent acrylic box.
In the next phase, trainers conducted the sequential object-action training sessions by sequentially presenting object and action requests (ball → fetch, ball → point, key → fetch, key → point, bottle → fetch and stick → point). Then, object and action items were combined into object-action simultaneous requests.
Finally, the researchers conducted simultaneous object-action control tests in different conditions such as with trainer wearing sun-glasses or trainer with mouth covered by a cloth band. Control tests were also performed by item reversal, and by presenting a new object composing new combination of items.
“In the study with Sofia, we wanted to know whether a dog would be capable of reacting appropriately to sentences identifying the independent meanings of each of its components,” Dr. Ramos said. “Ball fetch” was then composed of an object command (which should be discriminated from others) and an action command (which also had to be discriminated). After appropriate training, Sofia could do it!”
The results show that a dog may process independent items of verbal information provided in a single request and use them to organize her behavior.
“Our results emphasize the sensitivity dogs have to verbal signs provided by humans and show a cognitive competence that compose the basics for syntactical functioning,” Dr. Ramos concluded.
This study was sponsored by the Brazilian funding institution CNPQ-PIBIC 2001\2002.