Researchers in the United Kingdom have raised the possibility that dogs take into account a person’s ability to see food when they make a decision whether to eat it, based on three tests of different sets of dogs.
According to lead researcher Juliane Kaminski, Ph.D., a lecturer in psychology at the University of Portsmouth in Portsmouth, England, the studies were the first to determine whether illumination has any effect on dogs competing for food. “The dogs steal significantly more food when it is dark compared to when it is light,” say the study results, published in the online journal “Animal Cognition” in November 2012. “The results of these tests suggest that dogs are deciding it’s safer to steal the food when the room is dark because they understand something of the human’s perspective,” she says.For those of us who have lived with dogs for decades, we may think, “um, yes, and?” However, Kaminski says, “Humans constantly attribute certain qualities and emotions to other living things. We know that our own dog is clever or sensitive, but that’s us thinking, not them. These results suggest humans might be right, where dogs are concerned, but we still can’t be completely sure if the results mean dogs have a truly flexible understanding of the mind and others’ minds. It has always been assumed only humans had this ability.”
For the first part of the study, Kaminski and her research partners, Andrea Pitsch and Michael Tomasello, Ph.D., of the Max Planck Institute for Evolutionary Anthropology, used 22 pet dogs at least 1 year old who were “interested in food” and “comfortable without their owners even in a room of complete darkness.” All dogs had to have taken and passed a basic obedience class.
Before starting the test, it was determined that all the dogs understood the experimenter’s commands: “After the experimenter and the dog entered the room, the experimenter took a piece of food, showed it to the dog and walked to the predetermined location. Then the experimenter called the dog’s name to get his attention. While saying ‘Aus’ or ‘Nein’ (German: ‘Do not take it!’) with a strong, low-pitched voice, she put the food on the ground at the marked position. The command was repeated as often as required – until the dog stopped trying to eat the food. Then the experimenter slowly walked backwards and sat on the ground at the predetermined location. The trial ended after 60 seconds had elapsed without the dog taking the food. After the 60 seconds had elapsed, the dog was encouraged to take the food with the words ‘Geh ab!’ or ‘Jetzt nimm’s!’ (German for ‘You can take it now!’).”The experiment room was dark, with black polyurethane sheets over the windows. It was set up such that the food and the experimenter could each be illuminated separately by a 60-watt spotlight. “In the condition during which both areas were dark, illuminance was 0.1 lux [a measure of visible light per square meter] around both areas. When only one spot (either food or human) was illuminated, the illuminance in the illuminated area was 112 lux and in the non-illuminated area was 2 lux. When both areas were illuminated, the illuminance around both areas was 112 lux.”
The four conditions under which the dog’s willingness to take the food – despite being commanded not to – were Food Light/Human Light, Food Dark/Human Light, Food Light/Human Dark and Food Dark/Human Dark. In Food Dark/Human Dark, both spotlights were switched off.
To test each dog, the experimenter entered the room with the dog, showed a piece of food to the dog, turned off the ceiling lights, called the dog to get its attention, then, while placing the food on the floor told the dog, “Aus” or “Nein.” Then the experimenter walked backward to a predetermined spot and sat on the floor. “The trial started when the lamps were switched on or off by remote controls, depending on the condition.” After 120 seconds, the experimenter took the food if it was still there. The dog then had a 10-minute break before the next trial, ultimately doing a total of four under each lighting condition over four days.
This test found that “dogs took the food significantly more often in the Food Dark/Human Dark condition compared to all other conditions” and “significantly less often in the Food Light/Human Light condition compared to all other conditions. There was no significant difference between Food Light/Human Dark and Food Dark/Human Light conditions.”Many of the dogs took all four pieces of food when both the food and experimenter were in darkness. Two dogs took only one piece; three dogs took two pieces; and seven took three. Whether the dog was male or female had no effect on its actions. Only seven dogs took all four pieces of food when the food was dark and the experimenter was lighted. Five dogs took all four pieces when the food was lighted and the experimenter was darkened. Only two dogs took all four pieces when both food and experimenter were lighted, but then those two, Thyson and Zosi, took all four pieces regardless of the lighting situation. The dogs wore reflective collars so their movements could be more easily seen by the night-view video camera recording the experiment.
In the second test of the overall study, 12 dogs were taken individually into the room, then left alone with the food. In this case, both spotlights in the room were either on or off, and each dog was tested four times under each condition.
“The dogs took the food in almost all cases,” the report reads. Despite the lack of a person in the room, the dogs took the food “significantly faster when it was illuminated compared to its being in the dark.”
From this, the researchers concluded that “dogs’ behavior cannot be explained by a purely associative account of generally avoiding illuminated food. This is supported by the fact that in the current, non-social condition, dogs take the illuminated food even faster than the non-illuminated food.”In the third part of the study, 26 dogs were tested with an experimenter in the room – lighted or not – with the food lit to different intensities. Each dog was tested eight times. This test replicated those of the first test: “The dogs hesitated longer before taking the food when the food was illuminated than when it was not. They did so irrespective of seeing the human. The new finding here is that it is not only the general intensity of light around the food area that makes the dogs hesitate longer. Dogs’ decision when to steal the food is actually based on the specific location being illuminated.”
The fact that the dogs took into account what the person could or couldn’t see is “incredible,” Kaminski says, “because it implies dogs understand the human can’t see them, meaning they might understand the human perspective.” She adds, however, that more research is needed to identify what mechanisms control dogs’ behavior.
Kaminski researches “the evolution of human sociality with a particular focus on social cognition.” She is “especially interested in the individual’s understanding of others’ perception, knowledge, intentions, desires and beliefs,” according to her university staff web page. She does comparative research using people, the great apes and the domestic dog.
This article is based on Dr. Kaminiski’s published study and a press release from the University of Portsmouth.