Monday, August 27, 2007

The social smile of stuttering

I spoke to a friend of mine who leads a neuroscience research group, and explained to his astonishment that people with PDS can speak fluently under certain circumstances while singing, imitating a foreign accent, chorus reading, and acting. I also told him about the theory that there are two pathways involved in speaking: one that lets us talk without thinking how we talk, and one that lets us conscuiously modulate our speech. And he mentioned the social vs natural smile phenomena.

People can naturally smile, where they do not control how they move their face muscles, and give a social smile where they decide to smile (even if the joke was bad or they hate their opposite!). A social smile has evolutionary advantages because you can mask your own intentions for the greater good. So let me apply this analogy to stuttering.

When we make a "social" speech, we control how we want to come across. When we make a "natural" speech, we just talk and dont care or are aware of how we speak, it's done automatically. And, in people with PDS, the ability of "natural" speech is sensitive to all sorts of interferences!


Anonymous said...

Per Alm had already commented that in his excellent article On the Causal Mechanisms of Stuttering:

"The human brain has two parallel premotor systems, i.e. systems involved in planning and execution of movements, including speech. Both systems have the ability to provide go-signals for movements, but under somewhat different conditions. The lateral system, consisting of the lateral premotor cortex and the cerebellum, is active when the movement is controlled in relation to the sensory input — like when speaking to the pace of a metronome or reading in unison. Similarly, the lateral system is dominant when speech is controlled by auditory or somatosensory feedback.

In contrast, the medial system, consisting of the basal ganglia and the SMA, operates based on automatized programs without external feedback. This system is dominant during spontaneous speech, especially if the speech is propositional, i.e. that it conveys thoughts or emotions.

The lateral system is also assumed to be active when a movement is executed with increased attention and conscious control, while the medial system dominates for automatic responses. This is claimed to be the reason why it is difficult to get a natural smile when asked by a photographer — voluntary and spontaneous smiles are created by two different systems in the brain.

This distinction suggests that the lateral system is in charge when speaking in a way that is not automatic, like imitating an accent or playing a role. This dual premotor systems model of stuttering provides a novel explanation for most of the well-known fluency inducing conditions in stuttering. Stuttering is related to a disturbance of the medial system, but when the control is shifted from the medial to the lateral system the problem is bypassed.

As mentioned above, this could pertain to the metronome effect, unison reading, imitation of an accent, and role play. Furthermore, there are research data supporting that it is the lateral system that is dominant for go-signals during singing and rhythmic speech, conditions know to improve fluency."

Tom Weidig said...

I didnt copy from Per I swear!! :-)

Anonymous said...

Very, very, very true! When i speak under "stuttering" circumstances i feel like all my mouth is heavy. Like thinking more of how to make some muscle to move rather than what i want to say. Maybe we should give ourself a role of speaker and play it, rather than having that feel of guiltiness while we speak. Whatever
i think that this is the only explanation for the speaking fluent alone, and stuttering in front of people. We are just too aware of how we say the things

ac said...

Yep, this is one of the most interesting/frustrating aspects of stuttering.

When I was an undergraduate, I had a show on student radio - that's right, I used to introduce songs, interview people, and often simply talk for altogether too long because my fluency was so much better than normal.

Unlike a lot of people I don't fear public speaking, I crave it - for some reason my fluency gets a major boost in that situation. To catch is it needs to be prepared, and not spontaneous - for example asking questions in forums can be dicey.

I suppose this is the basis for the various speech modulation treatment techniques: by substituting the 'smooth speech' pattern uses different parts of the brain.

Stuttering Brain said...

Before everyone makes j-j-jokes, stuttering is more than just a speech thing, like not saying your “r’s” correctly or having a lisp.It’s actually a pretty rough brain disorder when people got too much dopamine (sorta like Schizophrenia) and synapses don’t connect. So you just wait until more words come, and while you wait your voice skips like a record.I’m now a great speaker, but it still swoops down about once a week to mess with me. Sorta blows.