Humans can use their voice to instruct dogs without words

Humans can communicate various instructions to dogs without using actual words – simply by modulating the tone of their voice, a new study from ELTE University’s Department of Ethology shows. By repeating the nonsense syllable ‘bü’ in different intonations, humans successfully signaled ‘Yes’, ‘No’, ‘Here’, and ‘There’ and, remarkably, dogs responded correctly, despite receiving no prior training. The findings reveal ancient acoustic codes, interpretable across species, that predate language itself. The study was published in Cognition, and a video abstract presenting it is also available.

‘Yes’ and ‘no’ are among the most commonly used words. But the origins of these simple meanings are older than language, and even older than humans. This raises the question: are there ancient vocal codes that we can still use today to communicate such simple meanings without words, also to other species?

To find out, researchers of the Neuroethology of Communication Lab, Department of Ethology, ELTE University designed a special experiment: they asked dog owners to hide behind a screen and freely modulate their voice but not to use words while communicating with their dogs. “Dog owners had to repeat the nonsense syllable ‘bü’ in various tones to intentionally convey four instructions: ‘Yes, come here!’; ‘Yes, go there!’; ‘No, don’t come here!’; and ‘No, don’t go there!’,” said Attila Andics, PI of the ERC-funded lab, senior author of the study. “We were very curious whether owners succeed in such a task, as shared acoustic codes across mammals have so far only been observed in vocalizations triggered by inner states and used self-referentially, but not in intentional communication.”

The researchers then collected the ‘bü-bü’ vocalizations to which the dogs responded correctly – surprisingly, there were many. This shows that we can convey specific instructions purely through the modulation of our voice, even without words. The research found that when people communicate ‘yes’ compared to ‘no,’ their voice is higher and smoother, with a more constant pitch, less noise, shorter and more frequent calls, and it is quieter overall. Interestingly, the ‘bü-bü’ vocalizations also encoded whether ‘yes’ and ‘no’ referred to ‘here’ or ‘there,’ providing the first evidence that nonverbal vocalizations can encode locations too. Interestingly, the acoustic profile of ‘here’ relative to ‘there’ was very similar to that for ‘yes’ relative to ‘no’, suggesting that both distinctions build upon the same ancient acoustic code – likely the one originally used to signal ‘Yes, approach me’ versus ‘No, don’t approach me!’.

“This isn’t about tricks or learned commands,” explained Anna Gábor, the lead author of the study. “It’s about tapping into an evolutionarily old communication system shared with other mammals – one that likely predates language itself.”

The findings suggest that dogs – and potentially other animals as well – can extract simple meanings from acoustic cues in the human voice, also beyond inner states, shedding light on how early humans may have communicated with animals before formal speech evolved. The study also implies that humans may be more skilled than previously thought at making use of ancient voice-acoustic codes, reminding us that speech is not the only efficient means of sharing thoughts by voice.

This study was published in Cognition titled “Cross-species acoustic codes for yes and no in human nonverbal vocalizations”, written by Anna Gábor, Fanni Lehoczki, Flavie Bensaali-Nemes, Tamás Faragó, Kinga Surányi, Attila Andics.

The study was funded by:

Eötvös Loránd University; National Research, Development and Innovation Office; Ministry for Innovation and Technology; European Research Council; National Brain Research Program