Faster and slower languages convey information at similar rates

Are some languages spoken faster than others? Are some structurally more complex? And, finally, are some better at transmitting information? These age‐old questions might have received a surprising answer in a new article published in the September 4th edition of Science Advances. The study, titled "Different languages, similar encoding efficiency: comparable information rates across the human communicative niche," conducted by an international and interdisciplinary team involving scientists at the Laboratoire Dynamique Du Langage/CNRS/Université Lyon 2 and Collegium de Lyon in Lyon, France, The University of Canterbury in New Zealand, Ajou University in Suwon, South Korea, and The University of Hong Kong in Hong Kong, reports the results of an information‐theoretical analysis of 17 languages.

"Surprisingly, we find robust evidence that some languages are spoken faster than others (for example, Japanese and Spanish speakers produce about 50 percent more syllables per second than Vietnamese and Thai speakers). Also, some languages 'pack' more information per syllable due to their phonology and grammar (for example, English has about 11 times more types of syllable than are possible in Japanese)," explains co‐author Dan Dediu. "However, more importantly, there is a trade‐off between the two such that 'information‐light' languages are spoken faster than the 'information‐dense' ones, balancing out at a rate of about 39 bits/second in all languages in our sample. Crazy, isn't it?" asks Dr. François Pellegrino, lead author of the study and expert in linguistic complexity. These findings point at the existence of a relatively narrow optimal rate of information transmission, probably due to constraints, deeply embedded in the way our brains work, on how fast language can be processed and produced. However, there are several ways this optimum can be achieved: either you pack lots of information in each one of the few syllables coming out of your mouth, or you produce many fewer informative syllables. "It is like bird wings: you may have big ones that need few beats per second or you have to really flap the little ones you got, but the result is pretty much the same in terms of flying," adds Dr. Christophe Coupé, senior author of the study. 

Language as a gingerbread reindeer: the two B/W versions use different resolutions and number of gray levels but encode the same info, just as languages trade off different strategies but are equally efficient
Language as a gingerbread reindeer: the two B/W versions use different resolutions and number of gray levels but encode the same info, just as languages trade off different strategies but are equally efficient © Dan Dediu, Université Lumière Lyon

Christophe Coupé et al. Different languages, similar encoding efficiency: Comparable information rates across the human communicative niche, Science Advances (2019). 

DOI: 10.1126/sciadv.aaw2594

Language is universal, but it has few indisputably universal characteristics, with cross-linguistic variation being the norm. For example, languages differ greatly in the number of syllables they allow, resulting in large variation in the Shannon information per syllable. Nevertheless, all natural languages allow their speakers to efficiently encode and transmit information. We show here, using quantitative methods on a large cross-linguistic corpus of 17 languages, that the coupling between language-level (information per syllable) and speaker-level (speech rate) properties results in languages encoding similar information rates (~39 bits/s) despite wide differences in each property individually: Languages are more similar in information rates than in Shannon information or speech rate. These findings highlight the intimate feedback loops between languages’ structural properties and their speakers’ neurocognition and biology under communicative pressures. Thus, language is the product of a multiscale communicative niche construction process at the intersection of biology, environment, and culture.