large and small news about language

What is the most ubiquitous human social activity?  I vote for conversation (see my post from 3/30/14).  The ease with which we carry on conversing belies the complexity of the matter:  listening and understanding is complex, formulating and uttering our next contribution is complex, taking conversational turns is not simple,  and keeping it all on topic and relevant seems more than some can manage.  We rely on social formulas, e.g., how’s the weather & how’s the family, to facilitate quick exchanges and we give more thought to our serious discussions.   Highlighting the skill needed to participate is the rapidity of our exchanges; a conversational turn may take less than a second and even long-winded turns generally take only a few seconds.  Yes, some people go on for sometime, but their listeners generally remember something else they have to do and move on.  Conversational turn-taking is so natural we have to learn to inhibit it in order to become listeners.  I learned this watching preschool story time where the initiates kept speaking up in response, that is only natural to them, but they eventually with the help of good teacher learn to just listen and save their participation for later, a very interesting process to observe.

To lose the ability to participate is really difficult and frustrating, as I learned working with stroke patients.  Many others lose the ability due to nervous diseases that impair motor control.  They listen and think of responding but the words won’t come, so it is a large report that scientists have developed a way to translate the brain’s motor speech impulses that are blocked from enactment directly into computerized speech.  I marvel at the complexity of translating the specific nerve impulses for the speech organs, i.e., lips, tongue, jaw, pharynx, larynx, etc., into the phonemes and then assembling those phonemes into coherent speech.  This study shows that this can be accomplished in principle and now the hard slog to make this augmentative communication practical begins.  I saw this large story at: https://www.nytimes.com/2019/04/24/health/artificial-speech-brain-injury.html.

The small story is from the 3/30/19 Science News about singing mice and duets. Who knew?  (Well, maybe Frans de Waal did—I just read in his new book about how mice communicate through high-pitched squeaks outside of our hearing range.  They ‘laugh’ when their tummies are tickled. That Frans de Waal is a tickling fanatic, see my post 4/8/16). Scientists found out that a species in Central America sing to each other and then they studied their brains as they did so.  They found that one neural area produces the song and another controls it for turn taking (hmm.  Sort of like our left hemisphere controls speech and the right manages the pragmatics of turn taking?)  They discovered this by using either cold or drugs to inhibit one area or the other. These ‘duets’ are better termed conversations, I think, and they are “carried out with split-second precision”. Oh, and if the turn-taking area is numbed, the songs grow longer.  Tell me about it.  Anyway, a small report of a finding that contributes to our understanding of the brains, the mice’s and ours, on the way to helping with communication difficulties.

With a large and small news report now posted, I will travel on.

Conversation, music and novelty

In my 2/14/14 post I talked about the hippocampus, an evolutionarily older area of cortex.  Information from posterior perceptual areas flows through the hippocampus, which processes it for context and novelty, then sends the results forward.  A good example can be seen when a cat hears a noise, freezes and orients to check it out, and then moves forward figuring what the new situation is.

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Novelty is more complicated than might be supposed.  Perceptually it is detected when something changes or when something expected to change doesn’t change as expected.  The change may be about something static, e.g., an object, or dynamic, e.g., a stream of sound or passing scent.  Something uninteresting may change because of changes within the animal.  Figure may become ground or vice versa.  Perceptually we respond to ambient energies but that response is a very creative task.

Now we return to the 3/30/14 post about conversation.  The left side processes the semantic, syntactic, and phonemic information of a sentence while the right processes the intonation or the prosody of the utterance.  What comprises novelty here is made even more complicated because we are creating the information as we make meaning, because the grammatical and pragmatic information pose different challenges but must be integrated, and because of the rapid and ephemeral exchange composing the communication.

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Maybe the hippocampi, right and left, are involved in this, but more likely higher cortical areas come into play as we understand a comment on a topic and then make our own new comment and then carry on, maybe even changing topics again while monitoring the interpersonal prosody for such things as changes in tone for sarcasm, excitement, joy, sorrow, etc.

An interesting feature of this processing comes when considering H. P. Grice’s 4 conversational maxims of quantity, quality, relevance, and manner.  Briefly, when conversing we expect people to say not too much or too little, to be clear, to be on topic and to be genuine.  These are probably not so much maxims as dimensions shaped by assumptions, so that when we detect a violation, that constitutes novelty.  When we hear a crash from the next room and ask our child what happened and he answers, “Nothing,” that is too little.  When someone goes off topic or becomes tangential or speaks unclearly or sarcastically or (we suspect) disingenuously we may interrupt and intervene to further successful communication.  Novelty of a different and rarefied sort.  Now on to music.

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Daniel Levitin in his book, This is Your Brain on Music, explains how new and old patterns or gestalts are important for music on several levels.  Different cultures have different musical keys which set up our expectations.  The progression of notes and tempo set up expectations which a skilled composer can exploit in order to express different feelings or concepts.  Our memory is important in catching on to the variations of themes.  A performer’s musicality depends in part upon their ability to vary timing and emphasis, etc., a fresh counter to the staid black and white score.  So novelty comes in various forms and guises, each important to the communication of symbolic import through the specialized channels of the MEMBRAIN.   Now this is getting interesting.  Next up?  Either my quibbles with Levitin or an introduction here to the arcuate fasciculus.

Basic conversation

Conversing is one of the most human things we do and we do it a great deal.  Our brains have evolved with special channels in and out for language.  Most people know of the posterior Wernicke’s area important to language comprehension and of the anterior Broca’s area important to language production.  These are basic to conversation of course.

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The speech signal is an unbroken stream of sound produced by air blowing through the vocal folds and then modulated by the speech tract (pharynx, nasal cavities, tongue, teeth, lips) to mark phonemes (vowels and consonants).  The auditory system processes this signal and somehow recovers the linguistic units to find words, sentences, etc.  Our brains do this rapidly and all at once, which makes it possible to interrupt someone to say what we want rather than listen to them. More on manners later.  Here is a graph of the speech signal for a sentence that took 1.5 seconds to utter (must have been a slow drawl at that).

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No breaks are between words, the stress or accent on different syllables is indicated by the amplitude of the graph, and the phonemes are there somewhere.  That is not the whole story, however, because while the left side of the brain is encoding/decoding the syntactic units, the right side is doing the same for the paralinguistic aspects of the signal, the intonation patterns carrying the sentence modality (statement, question, exclamation, etc.), the emotional cues therein, even the basics of the speaker’s identity, sex, age, geographic origin, etc.  This is done all the while as the right side also monitors the non-verbal cues for the listener’s interest and attitude along with the rest of the immediate concrete situation.  Again the left side’s language may be about information immediately available in the current situation but more probably is about information displaced in time and space, real or unreal.

The term ‘voice’ is used in many ways, a speaker’s basic necessity, a singer’s instrument, a poet’s distinctive mode of expression, etc. Biologically voice is the special sound to which our brains are attuned; a good part of our brains is dedicated to receiving and producing this figure so distinctive from the ground of ambient noises.  And not just humans.  The latest issue of Science News reports a study in which dogs were trained to lie very, very still in an MRI while sounds were played.  The results indicated that dogs also pay special attention to voice though not to the same degree as humans, which only makes sense given how well they engage with us and us with them in a special sort of conversation in which they are the better listeners and speak with their eyes, tongue and tail.

Coming soon: conversation and music

Mixed metaphors

Things are about to get complicated here as I mix some metaphors up. To begin I will post this optical illusion developed by Gestalt psychologists in the early 20th century.  They used it to illustrate that the brain’s visual perceptual system can operate with one gestalt at at time.

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You can focus on either the faces or the chalice but not both at the same time; one figure must be relegated to ground in service to the other. The gestalt theorists gave us a really good and useful concept there.  Simple enough.

Focus on the chalice for a moment.  Our biological roots have culminated in our symbolic capability.  Symbols carry meaning, so we must create meaning.  Symbols represent things even if those things are conceptual in nature; nothing like quarks or multiverses or Higgs fields or Zeus out there really.  For me the holy grail of neuroscience is to understand how our brains make meaning using symbols.  This may not be possible; it will certainly not be done easily.  Other goals, like understanding psychiatric disorders, are more important, but still, the pure science of the matter is that we seek to understand the basis of our humanity and this basis derives from our symbolization ability.  More later.

Focus on the faces for a moment.  Long years ago I became fascinated with conversations, the linguistics, the pragmatics, the paralinguistics of conversations.  Exceedingly commonplace with an endless variety of purposes and forms, conversations require that symbolic processing proceed rapidly, fluently, accurately about topics that are more often displaced in time and space and not immediately evident to our senses.  We converse by understanding another and expressing ourselves and the power and facility with which we do this is amazing.  Working as a speech/language pathologist I worked with children facing various challenges in conversing but they all wanted to converse just like they wanted to walk.  Conversing is in our nature and of course it is biological.  More to come.

So the optical illusion is a metaphor for the holy grail of neuroscience, symbolization, and for perhaps the most pervasive distinctively human behavior of all, conversation. One is ground for the other’s figure.  Stay tuned.