Have you ever come across an intervention that sounded strange to you? Have you doubted the efficacy of the method? If you have, it may have been a method whose underlying theory is not solid. You have naturally thought that there is something strange here, although you have not necessarily connected it to the theoretical background of the method.

A reliable theoretical background is important because it is connected to the method’s efficacy. If the method does not do what it is proposed to do, it is probably ineffective (see e.g. Rychetnik et al., 2002). The method can be used for many hours, but if it cannot bring about the desired change, no amount will help.

But how can we assess whether the theoretical background of an intervention method is reliable? Here are a few thoughts on the matter raised by research literature and my own research.

It is worth taking a look at the research literature as a starting point. What kind of research is there on the method in question in the client group we are interested in? Is there any research on the method regarding the relevant client group? What kind of results have been obtained? It is also worth remembering that the research should be independent, i.e. it should be carried out by someone other than an organization with a financial connection to the matter. For example, a company that sells products related to that method has financial dependencies.

If repeated positive results regarding the method are reported for the desired skills in the client group of interest, we can be quite confident about the theoretical background of the method.

Even if the efficacy of the method has not been proven by research, it does not automatically mean that the method does not work. The fact that there is no evidence on the efficacy of a method is not the same as there is evidence of the inefficacy of a method (Ebbels, 2014). It may be that there is no research on the method yet, but it could still be useful for our clients.

If there is no independent, high-quality research on the efficacy of the method, we should consider the theoretical underpinnings of the method. The theoretical underpinnings of the method indicate why the method is thought to cause the desired change, i.e. what is the mechanism of change. Assessing the theoretical considerations can help us to decide whether the method is worth using or not.

For example, the theoretical backgrounds of the following two methods are considered generally accepted. The first is a technique called recasting. In recasting, the child’s short or incorrect expression is repeated in a longer and/or correct language form. The proximity of the adult model to the child’s is thought to result in the child reanalysing the utterance and eventually incorporating the new structure or word into their language system (Gallagher & Chiat, 2009).

The second is the SHAPE CODING system. It is a metalinguistic method that aims to improve a child’s mastery of grammar rules by teaching them to the child (Calder et al., 2020; Ebbels, 2014). Usually, a child learns the grammar of his/her own language by listening and using it without knowing the rules. However, this is not always successful for children with Developmental Language Disorder. With the SHAPE CODING system, children are made aware of the rules of grammar so that they are better able to understand and produce the practiced grammatical structures.

Methods that are similar regarding their theoretical considerations and clinical execution as the intervention in question can also be used to help decision-making. If effective similar methods exist, we can assume that the method in question could also indicate efficacy even if there is no research on it yet.

Considering children with language disorders, there is a question that can be used to identify interventions that should raise a red flag regarding the theoretical background: Does the intervention target the area or domain of language where the child has challenges? If the child’s challenges are, for example, in oral language comprehension and the method aims to develop something more general, for example auditory processing, one should be cautious. Currently, there is no reliable evidence for improving language processing skills in children with language disorders so that linguistic skills develop as a transfer effect. Therefore, interventions should not focus on, for example, auditory processing, working memory, or auditory memory if the difficulties are in understanding or producing language.

I hope these reflections are useful when you assess the theoretical background of an intervention method and consider whether it is worth using with your client.

I wish you joy and increasing expertise for your work!

Best regards, Sirpa Tarvainen


Calder, S. D., Claessen, M., Ebbels, S., & Leitão, S. (2020). Explicit Grammar Intervention in Young School-Aged Children With Developmental Language Disorder: An Efficacy Study Using Single-Case Experimental Design. Language, Speech, and Hearing Services in Schools, 51(2), 298–316. https://doi.org/10.1044/2019_LSHSS-19-00060

Ebbels, S. (2014). Effectiveness of intervention for grammar in school-aged children with primary language impairments: A review of the evidence. Child Language Teaching and Therapy, 30(1), 7–40. https://doi.org/10.1177/0265659013512321

Gallagher, A. L., & Chiat, S. (2009). Evaluation of speech and language therapy interventions for pre‐school children with specific language impairment: A comparison of outcomes following specialist intensive, nursery‐based and no intervention. International Journal of Language & Communication Disorders, 44(5), 616–638. https://doi.org/10.1080/13682820802276658

Rychetnik, L., Frommer, M., Hawe, P., & Shiell, A. (2002). Criteria for evaluating evidence on public health interventions. Journal of Epidemiology and Community Health, 56, 119–127. https://doi.org/10.1136/jech.56.2.119