Dogs and their human companions: the effect of familiarity on dog-human interactions.

There are few quantitative examinations of the extent to which dogs discriminate between familiar and unfamiliar persons. In our study we have investigated whether dogs show differential behaviour towards humans of different degrees of familiarity (owner, familiar person, unfamiliar person). Dogs and humans were observed in eight test situations: (1) Three-way strange situation test, (2) Calling in from food, (3) Obedience test, (4) Walking away, (5) Threatening approach, (6) Playful interaction, (7) Food inhibition test and (8) Manipulation of the dog's body. Dogs distinguished between the owner and the two other test partners in those tests which involved separation from the owner (Test 1, 4), were aversive for the dog (Test 5) or involved playing interaction (Test 6). Our results revealed that the owner cannot be replaced by a familiar person in situations provoking elevated anxiety and fear. In contrasts, dogs did not discriminate between the owner and the familiar person in those tests that were based on obedient behaviour or behaviour towards an assertive person (Tests 2, 3, 7 and 8). Dogs' former training experience reduced the difference between their behaviour towards the owner and the familiar person in situations requiring obedience but it did not mask it totally. The dogs' behaviour towards each of the humans participating in the tests was consistent all over the test series. In summary, dogs discriminated between their owner and the unfamiliar person and always preferred the owner to the unfamiliar person. However, the discrimination between the owner and the familiar person is context-specific. This article is part of a Special Issue entitled: Canine Behavior.