It is obvious and incontestable that there is a sensori-motor aspect of speech. The whole, incredibly complex apparatus, has to be moved, co-ordinated, and continually adjusted with extreme precision. The engineering is extraordinary.
Speech involves a large number of muscles from the lungs to the lips. A muscle is activated from the brain by a signal passing along a pathway. The longer the pathway, the longer this takes. Long pathways have to be initiated before short ones. Almost all speech is on breathing out. The muscles of breathing, mainly the diaphragm and the muscles between the ribs, known as ‘intercostals’, are controlled by a different part of the brain from the muscles of the tongue and lips. So the messages to start breathing out have to be sent out by the brain some time before the first message for the first full-of-breath word. All of the different parts of this musculature have to be co-ordinated with one another irrespective of the different lengths of paths in order to achieve a particular phonetic result. And for this there are feed-back processes, checking the effects of the instructions, by listening to these effects and by feeling what is happening, where the tongue is in the mouth, whether it is touching the roof of the mouth, and so on. Fractional adjustments are made to the instructions according to the results by the feedback. The co-ordination of instructions and feedback is obviously intricate. The effect of any disruption of this feedback is obvious after a pain-killing injection by the dentist or by trying to talk if the sound of the speech is artificially delayed, as sometimes happens on a mobile phone. Speech gets disrupted, or becomes impossible.
In some cases, the chain of instructions is disrupted by a medically well-defined condition like cerebral palsy or physical trauma. Some children’s issues seem to be exclusively motoric without any medical diagnosis, as, for example, where the activity of one invisible muscle in the tongue triggers a corresponding activity of a highly visible muscle in the face. But in the absence of any known medical factor, such exclusively motoric issues are rare. So unless there is a clear medical diagnosis suggesting otherwise, the first diagnostic test in respect of any speech disorder should be whether it can be described in terms of well-evidencewd linguistic categories, independently defined by normal speech. Well-evidenced linguistic categories provide better, more precise guidelines for effective treatment than categories inferred from disorder. Of course, there may be no relevant linguistic categories. But that should be the last port of diagnostic call.
Although the act of speaking is often to achieve some goal, to interest, to persuade, to endear, to get information, and so on, which may work or not work, as the case may be, the way we order the words is quite remote from any goal we have in the utterance in which these phrases occur. The ordering is crucial. We say ‘good person’ and ‘someone good’ but not ‘person good’ or ‘good someone’. Person and someone are different sorts of words. What we do with words can be funny or honest or deceptive.
Some processes are forcibly linguistic rather than physical and perceptual. For instance, want to shortens to wanna only if there is a following word. “Do you wanna go? Do you really want to?” Like D and T before a syllabic L, the articulation of the T at the end of want and at the beginning of to looks forward to what is coming next. Such looking forward can’t be perceptual. And it isn’t plausibly motoric. Linguistic factors are forcibly involved. Children are normally learning about these seemingly small details at a very early stage in their acquisition of speech and language.
Although practise and familiarity are obviously relevant factors. this is not behaviour in the ordinary sense.