Using brain-imaging data and behavioral experiments, scientists have found that dogs might prefer praise from their owners over food.
This choice was uncovered by a new study that explored canine reward preferences published in the journal Social, Cognitive and Affective Neuroscience.
"We are trying to understand the basis of the dog-human bond and whether it's mainly about food, or about the relationship itself," said Gregory Berns, a neuroscientist at Emory University in the U.S. state of Georgia and lead author of the research.
"Out of the 13 dogs that completed the study, we found that most of them either preferred praise from their owners over food, or they appeared to like both equally. Only two of the dogs were real chowhounds, showing a strong preference for the food."
In this experiment, researchers began by training the dogs to associate three different objects with different outcomes. A pink toy truck signaled a food reward. A blue toy knight signaled verbal praise from the owner while a hairbrush signaled no reward and served as a control.
The dogs were tested on the three objects while in an fMRI machine. Each dog underwent 32 trials for each of the three objects as their neural activity was recorded.
All of the dogs showed a stronger neural activation for the reward stimuli compared to the stimulus that signaled no reward, and their responses covered a broad range.
Four of the dogs showed a particularly strong activation for the stimulus that signaled praise from their owners.
Nine of the dogs showed similar neural activation for both the praise stimulus and the food stimulus. And two of the dogs consistently showed more activation when shown the stimulus for food.
The dogs then underwent a behavioral experiment. Each dog was familiarized with a room that contained a simple Y-shaped maze constructed from baby gates.
One path of the maze led to a bowl of food and the other path to the dog's owner. The owners sat with their backs toward their dogs.
The dog was then repeatedly released into the room and allowed to choose one of the paths. If they came to the owner, the owner praised them.
"We found that the caudate response of each dog in the first experiment correlated with their choices in the second experiment," said Berns.
"Dogs are individuals and their neurological profiles fit the behavioral choices they make. Most of the dogs alternated between food and owner, but the dogs with the strongest neural response to praise chose to go to their owners 80 to 90 percent of the time. It shows the importance of social reward and praise to dogs. It may be analogous to how we humans feel when someone praises us."
The experiments lay the groundwork for asking more complicated questions about the canine experience of the world. The Berns' lab is currently exploring the ability of dogs to process and understand human language.
"Dogs are hypersocial with humans and their integration into human ecology makes dogs a unique model for studying cross-species social bonding."