Differentiating Between Apraxia and Severe Phonological Deficit

By Pam Marshalla

Q: I work at a clinic where my supervisor does not believe in apraxia. She says that all of these children have phonological deficit. What are your thoughts on this?

I sympathize with your supervisor in that I too struggled for many years with questions of apraxia–– What is it?  How is it diagnosed?  How is apraxia different from a severe phonological disorder?  The problem we are having is that we have taken the term “apraxia” from the adult neurological literature and we have applied it to children. The term is not a great fit.

The central question is: What is the difference between a severe phonological disorder and apraxia?

Think of it like this:  The children with whom we work need to learn better speech regardless of the etiology.  Children learn better speech by gaining new concepts about phonemes.  These new concepts are created in the mind as a result of taking in new information about phonemes.  New information is taken in via the seven sensory systems: Auditory, visual, tactile, proprioceptive, vestibular, gustatory, and olfactory.  The child with a “phonological deficit” can learn better speech by enhancing the auditory and visual input.  The child with apraxia needs more.

Phonological Deficit

A child with a “phonological deficit” can take in most of the new information he needs for learning better speech by using his auditory and visual senses.  We speak models in systematic ways, and the child watches, listens, and imitates.  The child improves dramatically as a result.

I call this “show and tell” therapy.  We show him what to do, and we tell him what to do, and he does it.  This is basically what we do when we use auditory bombardment, minimal pairs, cycles, storybooks, target words, and the other methods of phonological stimulation.  The old-timers called most of this “ear training” or “auditory training.”  The modern therapist calls this “phonological awareness.”

Some children learn easily and fairly quickly using this approach.  We all have seen children who go from near total unintelligibility to nearly perfect speech in 1-2 years.  We love those clients!  They tend to be very pleasant, they like coming to therapy, they make gains every week, and they tend to be fun to have on our caseloads.


Children with apraxia can be very different.  They don’t make rapid changes, they get stuck with certain phonological patterns, and they have much more severe and damaging phonological patterns.  These children do not gain new information about expressive speech very well when only an auditory and visual approach is taken.  When told, “Watch me… Do this,” they can’t, or won’t, or simply don’t.

A client with a much more stubborn phonological problem like this needs more than auditory and visual information to help him learn phonemes and phoneme sequencing.  He also needs methods to help him perceive his speech mechanism.  This seems to be the key idea that the researchers in our profession stubbornly avoid.  They perpetually investigate the speech patterns, the learning problems, the language needs, and the histories of apraxic children.  But they do not research the overarching sensory-motor learning needs of these children. They seem determined to avoid understanding what apraxia really is.

Tactile, Vestibular, Proprioceptive Problems

A Jean Ayres, OTR, PhD, was the first to identify sensorimotor integration disorder (1).  She taught that children with apraxia have difficulty organizing sensory information primarily in the tactile, proprioceptive, and vestibular areas.  She said that a child with apraxia moves, but he has difficulty “reading” these movements, and therefore he has difficulty developing appropriate body “maps” or “schemas” of his movements.  Each time he goes to move (i.e., speak) he has limited, incorrect, incomplete, and disorganized movement memories upon which to base his new movements.

The child with apraxia knows what he wants to say, but he cannot get his body to do it.  He has difficulty making a plan for speech movement.  It looks as if his problem is one of expression, but his problem actually is one of perception.  His problem in perception causes his problem in expression.  His problem in organizing incoming tactile, vestibular, and proprioceptive information causes him to have difficulty planning out how he is going to speak.  Therefore he chooses not to speak, or to speak very little, or he speaks with severe phonological error patterns because he cannot get his speech movement system to cooperate with what it needs to do.

Ayres is famous for saying that each time the apraxic child moves, it is as if he is moving for the first time, every time.  The SLP observes this as tremendous inconsistency in the speech of these children.  A child with severe apraxia can blurt out a word with perfect articulation one minute, and then be unable to say it the next.  Or he can do very well on certain speech skills one week, and then seem to be completely oblivious of this new learning the next.  Generalization is very poor, and new speech learning is very slow.  It is a very frustrating situation, especially because these children can be very bright.

Comparing Phonology and Apraxia

When I was in school doing research in phonology with Hodson and Paden (2), the pervasive philosophy was that the phonological analysis was simply a new way to organize the jumble of errors made by children who had “severe inconsistent multiple misarticulations.” Now, nearly 40 years later, we use the term “phonological deficit” to describe these children as if it was a category of speech deficit.

However, all children with severe expressive speech disorders manifest the same way.  They all have severe phonological deficit––they stop their continuants, omit stridency, omit consonants, reduce clusters, add voice where it shouldn’t be, and so forth.  Therefore even the apraxic child seems to have a “phonological deficit” because he does.  His phonological deficit is a manifestation of his apraxia.

The difference between the client with a “phonological deficit” and one with an “apraxia” is not simply a matter of severity.  The real difference is in the nature of the learning needs.

The child with apraxia simply does not learn speech through the typical auditory and visual stimulation methods of phonological therapy.  He needs more.  He needs help learning how his mechanism works through tactile, vestibular, and proprioceptive training offered in conjunction with his auditory and visual training.  Methods like PROMPT and oral motor have become popular in recent decades because these systems address the tactile and proprioceptive needs of the speech learning process.

I hope this helps you understand the difference between a severe phonological deficit and an apraxia.  Rest assured that this is a lifelong learning process.  Please see more ideas about apraxia on this blog, in my seminars, and in my books “Becoming Verbal with Childhood Apraxia” and “Apraxia Uncovered: The Seven Stages of Phoneme Development.”


  1. Ayres, A. J. (1980) Sensory Integration and the Child.  Los Angeles: Western Psychological.
  2. Rosenwinkel (Marshalla), P. (1976) Phonologically Based Therapy for Children with Multiple Misarticulations (Master’s Thesis).  Urbana: University of Illinois.  Thesis committee: Elaine Pagel Paden, Barbara Williams Hodson, and John J. O’Neill.

2 thoughts on “Differentiating Between Apraxia and Severe Phonological Deficit”

  1. I miss you Pamela!
    Your work reaches far.
    Thank you!

    Also a big thank you for keeping this info alive on the web!

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