Dogs are not as smart as previously thought ... Australian researchers find they 'cheated' on a famous intelligence test

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SYDNEY, 5 September 2006: Chimpanzees and two-year-old children are as clever as each other but dogs are not as smart as previously thought, according to a new Australian study.

Emma Collier-Baker, a psychologist at the University of Queensland, added tighter controls to a famous logic experiment in which a desired object – food or a toy – is transferred from a small container into one of three boxes.

Subjects then try to identify the box containing the object by pointing at it or walking over to it. This task, devised by developmental psychologist Jean Piaget in the 1930s, tests the ability to 'think' about an object that is not visible.

Several decades of research have revealed that great apes (including chimpanzees) perform the task as well as two-year-old children, while other animals such as monkeys, dolphins and cats consistently fail the task.

"Dogs were a surprising exception, repeatedly passing the task in several studies in the 1990s. However, our study – involving 35 dogs of various breeds – showed they were using other simple cues to find the object and not ‘thinking' or using logic after all," Collier-Baker said.

"By introducing a range of more stringent controls to the experiment, we showed dogs had effectively been ‘cheating' to pass the test and were simply going to the box closest to the small container."

By comparison, 21 two-year-old children, tested with identical apparatus to the dogs, were able to pass the task regardless of how close the container was to the target box, Collier-Baker said.

This finding threatened the validity of studies with other species which also lacked these control conditions. Collier-Baker therefore went on to test two chimpanzees, four gibbons (siamangs) and a spider monkey.

The desired object was food such as grapes or dried pawpaw for the apes, siamangs and the monkey, a tennis ball for the dogs and a small toy ball for the toddlers.

Unlike dogs, chimpanzees continued to find the hidden object under all control conditions, performing like two-year-old children on the task. The spider monkey failed the task, while the performance of siamangs was inconclusive.

Collier-Baker's findings on dogs were published in the Journal of Comparative Psychology. The chimpanzee study was published in the U.S. journal, Animal Cognition.

These results complement a growing body of evidence for shared cognitive abilities in great apes and two-year-old children.

Collier-Baker said she was continuing her research on gibbons.

"Gibbons are lesser apes and these primates have been surprisingly under-studied despite their value for reconstructing the evolution of primate cognition," she said. "Almost nothing is known about the cognition of these apes so my [studies are making] important inroads to gaining knowledge about them."