RESEARCH: Dog intelligence – does size matter?

Does size matter when determining the intelligence of a breed of dog? If a bigger dog has a bigger brain, does that make big dogs smarter than small dogs? As dogs increase in size, does their intelligence increase proportionately?

A new study in the Animal Cognition journal examines the intelligence of big dogs and small dogs. 

Daniel Horschler and his research scientists at the School of Anthropology at the University of Arizona in Tucson, America, conducted dog experiments with dog owners. He used ‘citizen science’ to help his research team collect dog information – specifically to research the mental capabilities of dogs.

The researchers established a website, called Dognition.com, with instructions for dog owners on how to participate in the cognitive experiments with their pet dogs in their own homes. The dog owners could also input their findings on the website for the researchers to collate.

There were 1,888 dogs with information. The researchers measured the size and shape of each participating dog breed’s skull as a comparison against size and against intelligence. 

Each dog owner participating in the research was provided with instructions on 10 tests to give their dog or dogs. The 10 tests enabled a series of functions to be examined. The researchers called this series of tests ‘a suite of cognitive abilities’ to test behaviour, memory, and inhibition. 

Some tests required repetition over time, while other tests were one-off tests of intelligence. One of the most useful tests of intelligence in animals is the ‘delayed memory’ test. The delayed memory test is when the owner puts a food treat – when the dog is watching – under one down-turned cup, leaving another cup with nothing underneath. The owner waits 60 seconds before releasing the dog, and testing whether the dog can find the treat under the correct (baited) cup. The dog owner repeats the test after a delay of 90 seconds, and again after a delay of 120 seconds, and finally after a delay of 150 seconds.  

The researchers found that for each of the 10 tests, there were statistically significant results of cognitive ability. The results were consistently the same.

The results showed a very clear trend indicating that larger dogs were able to accurately remember where the treat was over a longer period of time than smaller dogs. 

The researchers wrote that ‘the gap in performance between breeds of varying brain sizes generally widens as a function of increased cognitive demands.’ Larger dogs showed increased cognitive and mental performance. As the task became more difficult (more delayed time), larger dogs consistently performed better and quicker than small dogs. 

Daniel J. Horschler, Brian Hare, Josep Call, Juliane Kaminski, Ádám Miklósi and Evan L. MacLean (2019). Absolute brain size predicts dog breed differences in executive function. Animal Cognition, https://doi.org/10.1007/s10071-018-01234-1

Photographer: Martina Nicolls

Martina Nicolls: SIMILAR BUT DIFFERENT IN THE ANIMAL KINGDOM

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