Would you do speech therapy like this?

I was interested to read a paper about the relative efficacy of using traditional flash cards versus tablet presentation of pictures for articulation drill therapy because I have developed iPad apps myself (e.g., see www.DIALspeech.com) and have an interest in the potential of digital tools to enhance the speech therapy experience. The paper was recently published in the Online First section of Communication Disorders Quarterly by Krystel Werfel, Marren Brooks, and Lisa Fitton.

The study used a single subject alternating treatment design with four subjects, each kindergarten aged, —not clearly exhibiting signs of speech delay but none-the-less misarticulating two phonemes that could be practiced. Some statistical analyses (rather dubiously applied to single subject data) suggested that the children achieved mastery sooner in the flashcard condition but produced more correct responses in the tablet condition. To my eye, the data did not suggest a clear advantage to either condition. All the children did in fact master the treated phonemes (which were /z,s/, /pl,ɡl/, and /θ,ð/ (this pair for two children).

The authors make clear that the study is meant to be informative on the modality of stimulus presentation and not a test of the treatment protocol itself but I found myself alarmed at the possibility that readers might think that the treatment protocol would be reasonable in regular clinical practice and therefore I would like to address the way that the intervention was implemented. Often researchers implement a speech therapy intervention in a way that they would not in a regular clinical environment in an effort to exert more experimental control over all the variables than is typically necessary or desirable in an authentic clinical context. I can only hope that this explains some of the clinical choices that were made in this case. I am going to address several in turn as follows: (1) treatment approach; (2) treatment procedure; (3) reinforcement procedures; (4) cumulative intervention intensity; and (5) discharge criteria.

First, the authors state that they chose a traditional approach to therapy because there is empirical evidence that it works and clinicians prefer it. There is evidence of efficacy but in fact for most preschool aged children who qualify for speech services a phonological approach may be more efficacious as Francoise and I discuss in our text. Furthermore, the surveys indicating a preference for a traditional approach indicating that this is true in the United States but not elsewhere. Finally, there seems to be some confusion about what a “traditional” approach is. In some cases, traditional refers to a strict behaviorist intervention that focuses solely on speech production with a gradual increase in the complexity of speech units; in other cases it involves a sensory-motor approach with careful attention to variable speech practice and multiple targets; in other cases a traditional approach means Charles Van Riper’s approach which was properly sensory motor including both ear training, graduated speech practice and some principles of motor learning. The implementation in this paper was highly restricted involving only practice of single words and sometimes isolated sounds if necessary. If the speech therapist chooses a traditional rather than phonological approach it is best that the full sensory motor protocol be implemented.

Second, the drill based approach that was employed was selected again on empirical grounds. The study cited to support this approach was sound especially when treating children who have good speech perception abilities, most likely the case for the children in this study who did not have clear evidence of a speech disorder. Other approaches can be effective if procedures targeting phonological processing are incorporated into the intervention as shown by Hesketh and colleagues in the U.K. and also by me and Francoise with French-speaking children.

The strangest part of the whole intervention is that the children experienced over 25 treatment sessions each and throughout every session identical practice trials occurred: a stimulus prompt was presented, the child attempted to name the picture, the clinician provided feedback or extra support and then if the child’s response was correct he or she was permitted to mail the flash card or swipe the picture of the tablet. That was it. For eight weeks. I’m speechless. Enough said.

Regarding cumulative intervention intensity, I indicated in previous blogs that children should receive a minimum of 50 practice trials and ideally 100 practice trials per session. Furthermore, other single subject research using a minimal pairs procedures indicates that generalization goals are not usually met with fewer than 180 practice trials (when treating children with moderate or severe phonological delays). In Werfel’s study the children received treatment for two sounds in 20 minutes, so ten minutes per sound and 15 practice trials per sound or 10-minute block, therefore 30 practice trials per 20-minute treatment session. Reportedly, the mastery was achieved after 203 trials in the flashcard condition and 270 trials in the tablet condition (equivalent to 135 and 180 minutes of therapy respectively). However, increasing the number of practice trials to 50 during that 20-minute session could reduce the number of sessions or weeks in the intervention program by almost half. One way to do that would be to reduce the amount of feedback that was provided. The intervention was designed so that the clinician provided explicit feedback to the child after every practice attempt whereas the principles of motor learning suggest that less feedback is often better for speech motor learning. For example, a child can name five pictures in a row and be told that four of the five productions were correct. Another strategy is to practice at the challenge point at all times as described in detail by Francoise and I in Developmental Phonological Disorders: Foundations of Clinical Practice but also in our new undergraduate text Introduction to Speech Sound Disorders.

Finally, the discharge or stopping criteria in the study were set at 100% correct performance on the generalization probe over 3 consecutive sessions. The probe contained 5 treated words and 5 untreated words. This criterion meant that children practiced their targets for a long time past the point at which the practice material should have been made more difficult or the child should have been discharged to see if spontaneous generalization to natural speaking situations would occur. As Francoise and I review in Chapter 8 of our book, several studies have shown that children can be discharged after achieving between 40 and 80% correct responding on generalization probes. Most children will continue to make gains in production accuracy after this point. The four children in the Werfel et al study received an average of 5 unnecessary treatment sessions according to these criteria.

When conducting treatment studies, it is helpful to provide models of treatment procedures that are best practice in the clinical setting. Often interventions that are better than no intervention will prove to be effective in a research setting while not necessarily being best practice. These studies are confusing for a clinical audience I think. Furthermore, when asking clinical questions about new technologies it is interesting to ask, why would we want to bring it into our clinical practice? What benefit might it bring? How can we adapt these technologies so that the best of human interactions are retained and the most benefit of the technology is added? In my next blog I will address the Werfel study again, but this time imagining the questions we might ask about tablet-based implementations of articulation therapy.

Thinking about ‘Dose’ and SLP Practice: Part III

Continuing my discussion about the concept of ‘dose’ as applied to speech therapy, I finally get to the heart of the matter which is the issue of the optimal ‘dose’ of speech therapy to achieve the desired outcome which in our context is generalization of a phonology goal to untreated words. In previous blogs I discussed the definition of ‘dose’ in terms of the number of effective teaching episodes and the need to identify the effective ingredients of your intervention beyond the therapeutic alliance. Here I will discuss ‘dose’ specifically, as in how many effective teaching episodes are enough to achieve a good outcome in phonology intervention?

Let’s begin by returning to the pharmacology context from which the concept of dosage is borrowed. How is the concept helpful to physicians? First, it is important to know the optimum dose (or dose range) for average patients so as to avoid harming the patient. If the prescribed dose is too low the patient may not improve and the continuance or worsening of symptoms and disease will be harmful for the patient. If the dose is too high the medication itself may be toxic and harm the patient directly. Second, the patient’s response to the medication is diagnostic. If the maximum safe dosage has been prescribed and the patient is not responding favorably the physician must seek the reason: Is the patient complying with the prescribed treatment regimen? Is the patient doing something else that interferes with the effectiveness of the medication? Is the health care system administering the dose as prescribed? Does this patient respond to medications in an individualized fashion, such that a switch to another medication is required? Is the diagnosis wrong such that an entirely different treatment is called for? I will describe the research on appropriate dose in the case of meaningful minimal pairs therapy (applied to preschool aged children with moderate or severe phonological disorders) and we can consider whether these questions are relevant in the speech therapy context.

The method of meaningful minimal pairs is a uniquely linguistic approach to therapy that has the goal of changing the child’s production of an entire sound class. The procedure has two key components: (1) teaching the child pairs of words that differ by a single phoneme; and (2) arranging the environment so that the child experiences a communication breakdown if both words in a  pair are produced as a homophone. (SLPs and researchers usually get the first part right but often forget the second!) The method is directed at the child’s phonological knowledge and therefore should not be applied until after phonetic knowledge of the contrasting phonemes in the perceptual and articulatory realms has been established.

There is a lot of research involving this method and at least two papers have carefully documented the dose that leads to generalization from trained to untrained words/targets. More than 50% generalization is the outcome of interest because we know from other studies that you can discontinue direct treatment on the target pattern at this point and the child will continue to make spontaneous gains. The two papers that I will discuss have the further benefit of allowing the reader to count the “dose” precisely as the number of practice trials. The papers also provide information about the number of sessions and the number of minimal pairs over which the practice trials were distributed.

Weiner (1981) demonstrated that the method was effective with two children, using a multiple baseline design and treating deletion of final consonants (DFC), stopping of fricatives (ST) and fronting (F). Four minimal pairs were taught per target pattern and use of the pattern was probed continuously for treatment words and on a session-by-session basis for generalization words. The results do not show that much difference across target patterns but the response across children was markedly different with one child showing much faster progress than the other for all targets. For example, Child A reduced DFC to below 50% in treated words after 120 practice trials and in generalization words after 300 trials. On the other hand, Child B required 200 and 480 trials respectively to reach the same milestones for DFC. Furthermore Child A was able to accomplish many more trials in a session (e.g., 400 practice trials over 5 sessions for child A or 80 trials/session vs. 570 practice trials over 13 sessions or 43 trials/ session for child B). Despite this large variance in rate of progress across children, the study suggests that an SLP should expect a good treatment response with this method after no more than 500 trials.

This finding was replicated in a larger sample (n = 19) by Elbert, Powell and Swartzlander (1991). In this study a behaviorist approach was taken to the treatment of the minimal pair words in contrast to Weiner’s procedure that emphasized the communication breakdown as an important part of the procedure. The children were taught one pair at a time in series and the study was structured to determine how many children would achieve generalization to untreated words ,at a level of at least 50%, after learning 3, 5 or 10 pairs of words. They found that 59% of the children generalized after learning 3 pairs which took an average of 487 practice trials (range 180 to 1041) administered over approximately 5 20-minute treatment sessions; 21% of children needed to learn 5 word pairs (1221 practice trials on average) and 14% needed to learn 10 words pairs (2029 practice trials on average) before generalization occurred. This left 7% of children who did not generalize at all.

How can we use these data about dosage in our treatment planning? There is a lot of useful information here. First, we know that it is possible to achieve 80-100 practice trials in 20 minutes. Therefore, if your treatment sessions are 20 minutes long you can target one phonological pattern and if they are 60 minutes long you can target 3. Second, they show us that children do not usually generalize in under 180 practice trials (and I would argue that the data indicate that it is number of practice trials rather than sessions that is important). What harm might arise if you provide a child with the government mandated 6 annual treatment sessions, targeting three patterns, but failing to achieve more than 100 practice trials for each target pattern across the 6 sessions? We can predict that the child will not start to generalize before the end of the block and therefore will not continue to make spontaneous gains after treatment stops. When the next block begins the child may be discouraged and less cooperative with the next SLP. The parent may become discouraged and seek out complementary or alternative interventions that are even more useless or harmful than speech therapy provided with insufficient intensity!

What if the child has achieved more than 500 practice trials and has not generalized? At this point you have more than enough reason to reassess your diagnosis and/or your approach. Child B in Weiner’s study for example did finally achieve many practice trials but did so slowly because he was unable to achieve the recommended intensity, producing much fewer than 80 practice trials per session. This child also failed to generalization after 500 trials for one of his targets. Perhaps this child was lacking in the necessary prerequisites such as stable perceptual and articulatory representations for the target phonemes. Or, perhaps the child viewed the communication breakdowns to be the SLP’s listening problem rather than his own speech problem and thus a disconnect at the level of the therapeutic alliance was hampering the child’s learning.  What about the children in Elbert et al who did not generalize at all? It was eventually revealed in the paper that these children presented with many “soft signs” indicative of both speech and oral motor apraxia. Therefore, continuing to almost 3000 practice trials for these children was most assuredly harmful, given that they were not benefiting from the approach and they were deprived of the opportunity to experience a treatment approach better suited to their needs.

I am hoping that this example in the specific context of minimal pairs intervention demonstrates that the concept of dosage can be very useful in speech therapy. We need much more research that establishes typical ranges of ‘dose’ for optimum outcomes for any given intervention procedure that we use. Then we need to track these dosages as we apply procedures in our interventions. It is important to remember that the dose is not the number of sessions or visits by the child or family to the SLP. Rather, the dose is number of learning opportunities experienced by the child. When the child is not learning and we know the child has experienced the optimum dose of practice trials, we can adjust our intervention procedures with greater confidence. We can also set evidence based goals for our clients and document objectively their progress with respect to these expectations. In addition to these benefits for individual clients, this kind of information will allow us to evaluate the efficacy of our service at the program level with an objectivity that is currently lacking. Imagine if a government or an insurance company suggested that they save money by reducing the dose of our medications below effective levels! We should not allow this solution to be proposed to reduce the cost of speech therapy services. The only way to protect ourselves and our clients is with more research and greater specificity about how our treatments work. We must know the right dosage.