Take 5: What makes human language so special?

03/22/16 โ€“ BOSTON, MA. โ€“ Iris Berent, Professor of Psychology, gives the 52nd Annual Robert D. Klein Lecture held in the Raytheon Amphitheater at Northeastern University on March 22, 2016. Photo by Matthew Modoono/Northeastern University

Northeastern University psychology professor Iris Berent delivered the 52nd annual Robert D. Klein Lecture on Tuesday afternoon in the Raytheon Amphitheater. In her talkโ€”titled โ€œHow do human brains give rise to language?โ€โ€”Berent argued that human language is a product of a specialized biological system, that we are innately equipped with a language instinct.

โ€œPeople know how to talk in more or less the sense that spiders know how to spin webs,โ€ she explained, quoting the cognitive scientist Steven Pinker. โ€œSpiders spin webs because they have spider brains, which give them the urge to spin and the competence to succeed.โ€

Here are five takeaways from the lecture, which was established in 1964 and renamed in 1979 in tribute to the late Robert D. Klein, proยญfessor of mathยญeยญmatics and vice chairman of the Facยญulty Senate.

What makes human language so special?

โ€œWe humans are good at language,โ€ Berent explained on Tuesday. โ€œWe acquire language rapidly and spontaneously, and we are apparently unique in our ability to do so.โ€

For more than a decade, her research has focused on why, probing into one central question: What makes human language so special? As an expert in the phonoยญlogยญical strucยญture of lanยญguage, she has tackled the inquiry from a broad interdisciplinary perspective, using a diverse set of methods, languages, and research populations, including infants and children.

Her findings have been published in top scientific journalsโ€”including Language, Cognition, and the Proceedings of the National Academy of Scienceโ€”and her work has been funded by both the National Institutes of Health and the National Science Foundation.

A big brain

At the beginning of her lecture, Berent summarized the standard answer to why humans can acquire language while other nonhuman animals cannot, appealing to three generic yet distinguishing properties of our species.

One is our brain size. Another is our capacity to engage in social interactions. And the third is our highly refined auditory and articulatory motor control systems.

None of these capacities are specific to knowledgeโ€”a large brain, for example, also allows you to solve math problemsโ€”and Berent argued that theyโ€™re entirely insufficient to explain the language gap between a human and, say, a dog.

For her, itโ€™s more plausible to posit that language is a specialized biological system, to argue that we are innately equipped with a โ€œchipโ€ specifically designed for language.

After ruling out two prominent objections to this theoryโ€”including the so-called blank state hypothesis, which suggests that all knowledge derives from experience and perceptionโ€”Berent went on to show that the brain seems to behave like a specialized organ.

โ€˜Blif v. lbifโ€™

โ€œIf language is a specialized biological system,โ€ she told the audience, โ€œthen distinct languages should likewise share aspects of their design.โ€ And thatโ€™s exactly what her research has found.

Regardยญless of our mother tongue, she said, we prefer cerยญtain linยญguistic strucยญtures to others. Despite sigยญnifยญiยญcant difยญferยญences between lanยญguages as unreยญlated as Korean and Spanish, all of them seem to share the same set of unwritten rules that dicยญtate how sounds can be arranged to form words.

In a study pubยญlished in 2007, her team showed that all spoken lanยญguages favor cerยญtain sylยญlaยญbles. For instance, sylยญlaยญbles such as โ€œlbifโ€ are much less common across lanยญguages than sylยญlaยญbles such as โ€œblif.โ€ A later study showed that people are senยญsiยญtive to this rule even if neiยญther of those sylยญlaยญbles occurs in their language.

โ€œIn this view, the language system in the brain of every speaker is equipped with abstract universal principles that favor โ€˜blaโ€™ to โ€˜bnaโ€™ and so on,โ€ she explained. โ€œCritically, these principles are active even if you have never heard either.โ€

What babies can tell us about language

Later in her talk, Berent pointed to her 2014 study of newborn babies to show that the human brain forms lanยญguages based on an innate set of linยญguistic rules.

One-day-old neonates were presented with blocks of auditory syllablesโ€”either well-formed ones like โ€œblifโ€ or ill-formed ones like โ€œlbifโ€โ€”while their brain activity was monitored using near-infrared spectrometry.

Berent found that ill-formed syllables elicited higher activation compared to well-formed syllables, suggesting that the brain has to work harder to identify syllables that are worse along the hierarchy. โ€œThese results do not tell us precisely why โ€˜lbifโ€™ is disliked,โ€ she explained, โ€œbut the fact that you find it basically at birth suggests that this preference is likely innate, rather than one that is acquired by learning.โ€

Dyslexia and the brain

Understanding how the brain computes languageโ€”how neural activity gives rise to cognitive structureโ€”could have big implications for language-based disorders.

Dyslexia is a prime example. Although it is most often clasยญsiยญfied as a reading disยญorder, it is also well known to affect how indiยญvidยญuals process spoken lanยญguage.

In a 2013 study of both skilled and dyslexic readers, Berent and her colleagues were surprised to find that the dyslexic readersโ€™ phonological system was considerably stronger than their phonetic system.

โ€œIf language and speech are one and the same, then deficit to speech would surely compromise the language system as well,โ€ she explained on Thursday. โ€œBut if the systems are distinct, then it is conceivable that despite the problems to speech processing, the core of the language system is intact.โ€

She added: โ€œI think these results show how a detailed interdisciplinary approach to the language system can help illuminate the origins of speech and language disorders.โ€