I read through an interesting study last week that attempted to answer the question of what human cues a dog responds to most when it comes to picking between two options. The paper is not an easy read, so I think I’ll try to paraphrase it here for you. I apologize for any errors of interpretation or omission in advance and refer you to the paper1 itself for clarification — it’s available in its entirety at PLoS ONE.
Previous research and observation of human-dog interactions points to the canine ability to interpret and react to a variety of observable cues given by people. Take for instance those times when you’ve thrown a ball or stick while a dog is not watching and then try to direct a dog’s attention to it by pointing and other body language such as gazing toward it as well as using your voice. With experience, most dogs eventually "get" pointing (though I did have one who never did, but he never was the sharpest tool in the shed). If a dog understands what the gesture means, they may even go in the direction that a person points when other cues are telling them that the object in question is located elsewhere.
Scientists at the University of Milan decided to determine whether or not dogs would respond to a variety of different human cues (see below) and choose to eat the smaller of two portions of food offered. They divided the 149 dogs that were enrolled in the study into nine groups and ran one group through each of the following categories; to quote:
1. Independent choice — dogs were presented with a discrimination task between large and small quantity of food with no human intervention; this group formed the baseline against which all other groups could be compared
2. Non-social enhancement — the target stimulus was enhanced in a non-social manner (by lifting remotely)
3. Local enhancement — the (human) model approached the target stimulus
4. Stimulus enhancement — the model approached and picked the target stimulus up bringing it to the mouth (hand-food contact)
5. Ostensive enhancement — the model approached the target picking the food up, gaze alternating and talking to the dog
6. Voice — the model approached the target and talked with a high-pitched tone of voice without looking at the dog
7. Gaze alternation — the model approached the target and alternated her gaze between it and the dog
8. Voice + Gaze — as above combining both communicative cues
9. Hand-to-mouth — the model approached the target moved the hand from target to mouth but without making contact with the food.
Each of the dogs was tested six times under each of three conditions:
1. Neutral influence: Where the demonstrator showed an interest in one of the two plates, both of which contained one piece of food
2. No influence: The demonstrator showed no interest in either plate, one of which contained a large amount and the other a small amount of food
3. Counterproductive influence: The demonstrator showed interest in the plate containing the small amount of food and ignored the plate with the large amount of food.
Tomorrow: The results and what they mean
Dr. Jennifer Coates
1 Marshall-Pescini S, Passalacqua C, Miletto Petrazzini ME, Valsecchi P, Prato-Previde E (2012) Do Dogs (Canis lupus familiaris) Make Counterproductive Choices Because They Are Sensitive to Human Ostensive Cues? PLoS ONE 7(4):e35437.doi:10.1371/journal.pone.0035437