Kelso JAS, Tuller B, Vatikiotis – Bateson E, Fowler CA. Functionally Specific Articulatory Cooperation Following Jaw Pertubations During Speech: Evidence for Coordinative Structures. Journal of Experimental Psychology, 1984 10: 812-832.

The purpose of this study was to learn about motor control systems through the study of speech. The experimental intervention that provided insight into the coordination of movement was to disrupt the movement of the jaw during the utterance of simple syllables. The two words chosen were similar but required very different coordination of the jaw, tongue, and the muscles of speech. This allowed the researchers to determine if the adjustments made when the jaw movement was disrupted were pre-programmed; or whether they were specific to the word being uttered.

This blog will discuss a few of the (amazing) results that impact how we deal with our patients / clients in order to improve function. The first, and most globally relevant, finding was that despite the jaw perturbation, the subjects were able to speak the words correctly. In order to speak the word (motor function), the vocal chords, muscles, and tongue altered their actions. This new synergy, created almost instantaneously, demonstrated that the relationship between parts was not a fixed pattern. Rather, the parts were flexibly assembled to accomplish the task, and would adjust based on a change (jaw) without any conscious knowledge or previous experience.

So the synergies that our patients / clients create to accomplish a task are not “hard-wired” to run to completion once started. Our bodies have the ability to “adjust on the fly” to unexpected changes in the environment. So to maximize our patients’ / clients’ functional abilities, we need to alter our movement tasks. Tweaking the environment, or beginning position, or any of the other 10 Observational Essentials identified in CAFS (Certification in Applied Functional Science®) is a way to coax the body into creating new synergies. (Find out more here:

A second finding was that the adjustment in the motor components of speech were different depending on which syllable was to be spoken. Since the adjustments are not pre-programmed, then they depend on the task. But they also were dependent on when in the utterance sequence the jaw was disturbed. In motor control terms the synergies (and adjustments) would be described as task-specific and context dependent.

Therefore, we need to base our choice of movements on the task(s) our patients / clients need or want to do. If we understand the Chain Reaction® Biomechanics of the task, we are able to create functional movements that involve the same joint motions, muscle actions, and drivers of the task. Changing the environment and initial position of the body results in a change of context for the movement system. Subtle challenges to successful movement will produce even more success. 

A third finding was that many of the adjustments in the speech articulators to create the new synergy occurred in less than 30 milliseconds. A shorter time than the tendon reflex arc that travels from the patella tendon to the spinal cord and back to the quadriceps muscle. Much shorter than any neural path that would allow a message to travel to the brain and have the brain send corrective instructions.

So adjustments to synergies during functional movements are, for the most part, subconscious. Our patients / clients are aware of the task to be performed, but should not be attempting to consciously activate muscles. Our job as movement practitioners is to design and tweak global body movements that will produce the joint motions and muscle activations that are desired. 

This article was published 35 years ago, but the “lessons” it teaches have not been “learned.” Why? The educational programs of all professions are slow to change. Without the perspective that the body is an integrated system, practitioners’ attempts to enhance function will remain focused on isolating joints and muscles. Where should a movement specialist begin to acquire functional knowledge and skills? The Analysis Movements and Performance System Strategies of 3DMAPS® (3D Movement Analysis & Performance System) can serve as powerful tools for functional training and rehabilitation.

(Find out more here: