Happy Thought for 18 October 2024

Have a Happy Thought:   

Most of us humans tend to speak more slowly with dogs than we do with other humans. And it turns out, there may be a very good reason for this.

You see, human brains, when producing or listening to sounds, tend to operate on a brainwave pattern that peaks about four times per second – known as theta waves. 

 

On a side (but related) note, many of you have listened to someone speaking in a language that you don’t understand, and may have noticed that this other language sounds “fast” to you. Well, it turns out that some languages do use more syllables-per-second than other languages. And there doesn’t seem to be any pattern to how ‘quickly’ languages are spoken. 

As a visual, here is the average number of syllables-per-second spoken by native speakers of various languages 

 

Image: Syllable rate, in syllables per second, across 17 languages from multiple language groups. Figure from Christophe Coupé et al., Different languages, similar encoding efficiency: Comparable information rates across the human communicative niche.Sci. Adv.5,eaaw2594(2019).DOI:10.1126/sciadv.aaw2594 

 

Meanwhile, some languages have really long words (lots of syllables per word) while other languages tend towards short words (few syllables per word). If you think about it, this means that languages with short words tend to pack more information, per syllable, than languages with longer words. We will call these ‘short-word’ languages “dense” for the sake of this conversation. 

 

It wasn’t until someone put those two elements together before they started to see a real pattern: basically, it’s not only how many syllables you say in a second that matters to our brains. It’s also about how much information you’re getting across per second. So a “dense” language will tend to be spoken more slowly – giving the listener’s brain time to decode those “dense” syllables. Whereas a “fluffy*” language’s syllables can be spoken more rapidly, and still contain the same amount of information. 

Wherever your language falls on the dense-fluffy spectrum, you will tend to speak at a speed that ends up getting across 30-50 ‘bits’ of information per second.  

 

Image: Information rate, in bits per second, across 17 languages from multiple language groups. Figure from Christophe Coupé et al., Different languages, similar encoding efficiency: Comparable information rates across the human communicative niche.Sci. Adv.5,eaaw2594(2019).DOI:10.1126/sciadv.aaw2594 

 

Therefore, speech processing in humans seems to be done by a combination of theta (3 to 8 Hz) and gamma waves (roughly 30 to 100 Hz). It seems that the ‘theta’ brainwaves are picking up on rhythms in speech (the first image), and the gamma waves are unpacking the specific, and specially the complex, meanings (the second image). 

 

Okay, back to dogs. (This is also my chance to remind you of the fact that the ‘scientific’ name for dogs is “Canis familiaris” - familiar dog. 🐶)

Dog brains pick up verbal cues using a brainwave (Delta) that peaks twice per second, or about half the speed of humans’ brains when listening to speech. How do we know this? Some researchers put portable EEG machines on some dogs and spoke commands to the dogs. The dogs followed the most commands when the rate of human speech matched the dogs’ brainwave speeds... of about two syllables-per-second. And since this two-per-second seems to match the average vocalisation speed of dogs, even in the wild, this all makes sense! 

 

In other words: your instincts are right, and you should absolutely keep using dog-talk (slow your speech) to get your point across to your dog friends :) 

 

Let’s be honest, though – the only reason you’ve read this far is to see pictures of dogs with portable EEGs on their heads, so here you go: 

 

Image: https://www.newscientist.nl/app/uploads/dog-EEG.jpg 

 

Image: photograph by Vivien Reicher https://www.eurekalert.org/multimedia/742487 

 

 

Image: Photo: Elodie Ferrando, https://royalsocietypublishing.org/doi/10.1098/rsos.200851 

 

*dense and fluffy are my words for this phenomenon – if you’re an actual linguist, please don’t be mad!