What do dogs understand about us? Pointing, Rico and Chaser

Dogs understand a surprising amount about us, though not everything people credit them with. They can react appropriately to human body language such as gesturing and pointing, and they understand human voice commands. Two border collies, Rico and Chaser, also showed that a dog can learn the names of hundreds of objects.

Take pointing. In one task a reward was hidden under one of two buckets, and the experimenter signalled where by tapping, pointing, nodding or simply looking at the bucket. The dogs followed these signals, doing better than chimpanzees, wolves and human infants, and even puppies with limited exposure to humans did well. Cats, elephants, ferrets, horses and seals can follow a human point above chance, but dogs can use different types of point and perform about as well as two-year-old toddlers.

Then there are words. Rico knew the labels of over 200 items, and when given a new item he inferred its name by exclusion, knowing that the new item was the one he did not already know. He correctly retrieved such new items immediately and four weeks after first meeting them. Chaser went further: working with the psychologist John W. Pilley, she could identify and retrieve 1,022 toys by name, the largest tested memory of any non-human animal.

Do these dogs understand us the way we understand each other? Not necessarily. Excitement about dogs' fast-mapping should be tempered, and scientists still argue about why dogs read us so well.