Dog intelligence is the ability of a dog to learn, think, and solve problems. Dog trainers, owners, and researchers have much difficulty agreeing on a method for testing canine intelligence.
Dogs are able to read and react appropriately to human body language such as gesturing and pointing, and to understand human voice commands.
Evaluation of intelligence
"Intelligence" is hard to define, whether in dogs, other animals, or humans. The ability to learn quickly might be taken as a sign of intelligence, but such evidence must be interpreted with care, because learning speed may be affected by such things as the effectiveness of the rewards used in training or the motivation or activity level of the dog. For example, some breeds, such as Siberian Huskies, are said to be not particularly rewarded by pleasing their owners, but quickly learn to escape from yards or catch small animals, often using ingenious ways of doing both. Various studies have attempted to estimate intelligence by measuring the number of words or signs a dog can learn. A recent example by animal psychologists Juliane Kaminski and colleagues reports that Rico, a Border Collie, could learn over 200 words. Rico could remember the names of several items for up to four weeks after its last exposure (Kaminski et al. eliminated the Clever Hans effect using strict protocols). Rico was also able to interpret phrases such as "fetch the sock" in terms of its component words (rather than considering its utterance to be a single word). Rico could also give the sock to a specified person. In 2008, Betsy, also a Border Collie, was featured on the cover of National Geographic Magazine. Betsy's intelligence rivaled that of Rico's in that she knew over 340 words and was able to connect an object with a photographic image of the object, despite having seen neither before.
In 2013, Dr. John Pilley, a professor emeritus of Wofford College, published his book Chaser: Unlocking the Genius of the Dog who knows a Thousand Words,  within which he documented the intellectual capabilities of his border collie, "Chaser", who had learned the names and could associate by verbal command over 1000 words at the time of its publishing. Chaser was documented as capable of learning the names of new objects "by exclusion", and capable of linking nouns to verbs. Central to the understanding of his border collie's remarkable accomplishments, Pilley argues, is the dog's breeding background. He argues that border collies bred for herding work are uniquely suited for intellectual tasks like word association which may require the dog to work "at a distance" from their human companions; Pilley credits his dog's selective breeding in addition to rigorous training for her intellectual prowess.
In his 1996 book Good Natured, ethologist Frans de Waal discusses an experiment on guilt and reprimands conducted on a female Siberian husky. The dog had the habit of shredding newspapers, and when her owner returned home to find the shredded papers and scold her she would act guilty. However, when the owner himself shredded the papers without the dog's knowledge, the dog "acted just as 'guilty' as when she herself had created the mess." De Waal concludes that the "guilt" displayed by dogs is not true guilt but rather the anticipation of the behavior of an angry superior in a given situation.
Psychological research has shown that human faces are asymmetrical with the gaze instinctively moving to the right side of a face upon encountering other humans to obtain information about their emotions and state. Research at the University of Lincoln (2008) shows that dogs share this instinct when meeting a human being, and only when meeting a human being (i.e., not other animals or other dogs). As such they are the only non-primate species known to do so.
School psychologist Kathy Coon developed the first intelligence test for dogs in 1976, with the work continuously revised through 2003. Assessments were developed to test short term memory, agility, ability to adapt, problem solving, unique detour problems, and to see how the dog reacts to conditions which he or she finds unacceptable. The performance of individual dogs was compared to over 100 dogs on which the test was standardized. Additional breed norms were developed in her book, The Dog Intelligence Test.
- Cimons, Marlene (Jan 6, 1999). "New Drug Can Let Pooch Avoid Living a Dog's Life; Medicine: FDA OKs antidepressant aimed at helping to ease separation anxiety some neurotic canines experience.". The Los Angeles Times. Retrieved 2011-12-05.
- Gjersoe, Nathalia (Sep 23, 2013). "Dogs: an uncomplicated relationship". The Guardian.
- Kaminski, Juliane et al. (2004). Word Learning in a Domestic Dog: Evidence for "Fast Mapping". pp. 1682–1683 doi=10.1126/science.1097859.
- Morell, Virginia (March 2008). "Minds of their Own". National Geographic. Retrieved 2008-10-13.
- Pilley, John (2013). Chaser: Unlocking the genius of the dog who knows a thousand words. Houghton Mifflin Harcourt. ISBN 9780544102576.
- de Waal, Frans (1996). Good Natured. Harvard University Press. pp. 107–108. ISBN 0-674-35660-8.
- "Test reveals dogs' jealous side". BBC News. 2008-12-08. Retrieved 2010-05-01.
- "Functional MRI in Awake Unrestrained Dogs". PLoS One. 2012-05-11.
- K Guo, C Hall, S Hall, K Meints, D Mills (2007). "Left gaze bias in human infants, rhesus monkeys, and domestic dogs". Perception. 36 ECVP. Retrieved 2010-06-24.
- Alleyne, Richard (2008-10-29). "Dogs can read emotion in human faces". Daily Telegraph. Retrieved 2010-06-24.
- Coon, Kathy (1977). the dog intelligence test. Avon Books. ISBN 0-380-01903-5.
- Cunliffe, Juliette (2004). The Encyclopedia of Dog Breeds. Parragon Publishing. ISBN 0-7525-8276-3.
- Fogle, Bruce (2000). The New Encyclopedia of the Dog. Doring Kindersley (DK). ISBN 0-7894-6130-7.