Lindsay_Helms/iStock.com

Up, pup! Dogs, like humans, associate high-pitched sounds with lofty objects

Listen to a high-pitched note like the sound of a whistle and you’re likely to imagine something high off the ground. Dogs, it turns out, may have the same reaction, according to a new study. The findings might point to a “shared, evolutionarily older mechanism” for why we associate certain sounds with specific physical traits,” says Anna Korzeniowska, one of the authors of the study and an animal behavior scientist at the University of Sussex in Brighton, U.K.

Numerous studies have linked high-pitched noises not only with elevation, but also with bright or small objects. These links might arise through experience; smaller animals such as mice and birds typically make higher-pitched sounds, whereas large animals like bears vocalize at a lower pitch. Alternatively, the links could be due to existing features of the English language, such as using the words “high” and “low” to describe both pitch and elevation.

But for some sound-sight pairings, scientists haven’t been able to find a logical explanation; high pitches, for example, are thought of as bright and glowing, whereas low pitches are often interpreted as “dark.” To date, no hypothesis has been able to fully explain why we might associate a high note with these different sensory experiences.

Enter dogs. Researchers recruited 101 canines (no, they weren’t all Dalmatians) and showed them animations of a ball moving up and down. Sometimes the ball would be accompanied by a sound that became higher in pitch as the ball moved up and lower in pitch as the ball moved down or vice versa.

The researchers were able to extract 64 usable trials and found that overall, the dogs spent about 10% more time following the ball when the accompanying sound raised in pitch as the ball lifted. This likely means that the animals associate the rising of a pitch as “higher” in elevation, the researchers report today in Biology Letters. The finding suggests the link between pitches and position in space goes deeper than just language—it could be an innate knowledge shared by several kinds of mammals, and possibly passed on through animal family trees, the authors say.

“There is some evidence in favor of that idea,” says Marcus Perlman, a cognitive scientist at the University of Birmingham in the United Kingdom who was not involved with the work. Perlman says the design of the study is “reasonable,” but there could be confounding factors. For instance, the owners—who were sitting near the dogs during the experiment—might have given their pups some unconscious cue when the pitch and the ball raised in tandem, despite the researchers’ best efforts to prevent this. Also, the dog owners could have trained the dogs with verbal cues that caused them to associate a lower-pitched voice with something on the ground, and vice versa.

An interesting follow-up study, Perlman adds, would be to look at dogs whose owners spoke languages that do not associate pitch and placement in space, such as Farsi. Farsi speakers tend to associate higher pitch with “thinness” and lower pitches with “thickness.” If owners contribute to their dogs’ audio-visual associations, dogs of Farsi speakers might pay close attention to a shape thickening in tandem with a falling pitch. Although there’s always the chance the dogs would just associate the change in width with a nice thick slab of bacon.

*Correction, 13 November, 3 p.m.: This story has been updated to include input from one of the study authors.