Still no evidence for PROMPT

Some readers may wonder why Francoise and I did not mention PROMPT therapy even once in our book even though Chapter 10 does discuss interventions for Childhood Apraxia of Speech (CAS). The reason is that we found out, when we were using the very excellent Williams, McLeod & McCauley (2010) book for teaching, that students believe that if a treatment is mentioned in a text book that it must be a “good” treatment. Even when provided with information about levels of evidence and so on, the students could not or would not distinguish between treatments that were and were not evidence based. So when we wrote our book we decided to refuse to mention interventions that were in our view NOT evidence based and PROMPT definitely fell into this category. So, when I noticed an “in press” manuscript at the AJSLP site promising evidence in support of this treatment, I thought, ok, maybe we’ll have to add it to the next edition (getting ahead of myself here I know but I’m an optimist). Anyway, back to PROMPT…

The paper, Dale and Hayden (in press) reports 4 case studies in which probe scores for untrained words related to three goals per child are provided at 9 time intervals: baseline, phase 1, phase 2 and follow-up. There are three base-line probes, 2 in each of two treatment phases, 1 just post-treatment and a second follow-up probe 3 months post-treatment. Two of the children received the “PROMPT” intervention without the tactile prompts during the first phase and the full PROMPT intervention with the prompts in the second phase. The remaining two children received these treatment phases in reverse order. The abstract states “untreated word probes provided evidence for more gain when tactile cues were included”. Here is a table summarizing a rough description the untreated word probes as shown in Figures 1 through 4 (I have shaded periods associated with the full PROMPT intervention):

Dale Hayden figure summary

Some may quibble with my interpretation based on the statistics shown in the tables but I don’t agree that these statistical interpretations are valid given that the design is not a proper single-subject design. It is not a multiple baseline design and the nature of the study ensures that a withdrawal design is not appropriate to the question. The baselines are not stable and the probes are not administered frequently enough for a statistical interpretation. I find nearly all of these single-subject treatment studies in SLP to be extremely difficult to interpret in fact and prefer a single-subject randomization design in which a statistical analysis is fully appropriate as I have described in a previous blog post.

Notwithstanding the questionable interpretation of the findings in this study, I am even more bothered by a strange interpretation of the DIVA model in the introduction where it is stated that “In Guenther’s model, early speech learning relies on sensory feedback from the proprioceptive system, which eventually gives way to the auditory modality as the primary source of feedback information.” This misrepresentation of the model is used as a justification for the tactile cueing system used in PROMPT. I would say that, to the extent that their statement makes any sense at all, it is more or less backward, given this direct quote from Callan et al. (2000): “The speech production system must establish a mapping that is able to move the articulators in a manner to reach learned targets, taking into account the current context of the system. Auditory feedback of self-produced speech may serve as an adaptive signal that could establish a mapping that guides the movements of the articulators in order to reach auditory targets”. I have discussed the role of the auditory target and auditory feedback in the development of speech motor control in an open-access paper in relation to speech sound disorders as well (Shiller, Rvachew, Brosseau-Lapre, 2010). During learning auditory and proprioceptive feedback are crucial; over time feedforward control of speech becomes possible, as I describe in Rvachew and Brosseau-Lapre (2012): “The forward model tracks the vocal tract’s position in auditory planning space without relying on auditory feedback; rather the position of the vocal tract is determined by a prediction based on the known consequences of executing the motor plan combined with actual somatosensory feedback during production of the syllable. This information allows for continuous updating of the feed-forward command as the vocal tract moves to target…”. My concern, based on our current studies of children with CAS, is that interventions that provide too many external cues may interfere with the child’s access to and integration of different sources of feedback during the production of speech movements. I’ll have more to say about this potential problem as we begin to publish this work. In the meantime, I hope that readers will be wary of “single subject designs” that are not actual experiments. I also look forward to talking with people about these issues at ASHA 2013 where I will be presenting both a poster and a seminar on CAS interventions.

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8 Comments

  1. Elissa Flagg

     /  June 10, 2014

    I enjoy your blog very much and I’m learning a lot from it. I have a question about this statement:

    “My concern, based on our current studies of children with CAS, is that interventions that provide too many external cues may interfere with the child’s access to and integration of different sources of feedback during the production of speech movements.”

    Do you mean that it’s important to fade al types of cueing as soon as possible, or that there are certain kinds of cues (like tactile PROMPTs) that are in principle deleterious to the child’s development of speech motor control? Or something else?

    Reply
    • Thank you very much for your question and your comment. The concern that I raised about prompts and cues of any type interfering with generalization stems directly from our experience with children like the child described in my most recent blog post Auditory Motor Integration Intervention and CAS. That child show reasonable performance during therapy sessions when external cues were used but no learning/maintenance/generalization with this approach and that child has a true apraxia. That being said we are seeing a lot of other children who have phonological memory deficits and we find that external cues in place of imitative models is a good approach. I will write another blog post about those children specifically. So the question about external prompts and cues are, to my mind: are all external prompts similar in effect or does it really matter whether the prompt is tactile, graphic, gestural etc? Are these kinds of prompts only indicated for certain kinds of patients? Should these kinds of cues be paired with imitative models or take the place of imitative models? And of course, as you mention it is advisable to fade prompts as soon as possible in all cases.

      Reply
  2. Gabrielle Miller

     /  June 10, 2014

    I similarly enjoy your blog posts!

    Can you explain what the difference is between and external cue and an imitative model? If an SLP is providing an auditory model, isn’t that in essence external to the child – “an external cue”? Does “external cue” have a very specific meaning that I have not encountered?

    “That being said we are seeing a lot of other children who have phonological memory deficits and we find that external cues in place of imitative models is a good approach.”

    Reply
    • That is a good question too because of course you are right! An imitative model also provides an excellent external cue for production of the target. Tactile cues, graphic cues, and gestural cues provide additional information. I hope to have time this coming Sunday to write about how we have been using these cues cues in place of imitative models with some children, essentially using Barbara Dodd’s core vocabulary approach except that we are teaching no words. Barbara Dodd says that the imitative models provide the plan to the child whereas we want the child to construct the phonological plan more independently – these other visual cues can be used to stimulate a more spontaneous response and then faded.

      Reply
  3. Elissa Flagg

     /  June 10, 2014

    Thank you for your reply. I look forward to your future posts about different types of cueing and their impact on children with different profiles. As a clinician, I struggle with the balance between providing cues to support motor skill development, and facilitating maximal independence by encouraging development of strong target representations and an ability to self-monitor output and self-repair.

    Reply
  4. suzana yoder

     /  November 5, 2015

    I found your blog searching for reviews on PROMPT, which is the therapy the SLP I have taken my son to recommends using. I am an intervention specialist and was expecting his therapy to be play based. My son is 20 months old, and speaks just the word “mama”. He has met other milestones, gross and fine motor skills in line with typical development, he plays and interacts age appropriately as well. He uses a variety of sounds in babbling, but communicates through pointing, pulling and an “uh” sound. I know that isn’t enough for you to have a full picture of his abilities and needs, but I am looking for some feedback regarding prompt. I don’t want to him to engage in a therapy that is more invasive and intense than it needs to be. Any advice you have would be appreciated. Thank you! – Suzana

    Reply
    • I can only recommend that you get an opinion from a second SLP if you are looking for a more play based approach. I cannot offer any clinical advice about a specific case.

      Reply
  1. How to choose a control condition for speech therapy research | Developmental Phonological Disorders

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