Aldridge (1994) noted that single case studies, as well as being the primary source of music therapy research (Accordino et al., 2007), were ideal for creative arts therapists. Single case study designs have been used within a number of music therapy and related intervention studies with autism (Kern et al., 2007; Simpson and Keen, 2011; Reichow et al., 2011; Geist and Hitchcock, 2014; Villafuerte et al., 2012). The following provides an overview of the approach.
According to Alridge (1994), single case study designs allow clients to express themselves over a period of time. They allow changes in the relationship with a therapist and with other family members to be noted using a variety of methods. Changes in emerging phenomena, such as new intervention, can be detailed and new models can be created. Therapists discuss cases within their working environment, and case studies attempt to formalise that process (Geist and Hitchcock, 2014). However, Aldridge goes on to suggest that validity of success can be open to question due to the subjective bias of the therapist and client expectations. He states that these difficulties have been addressed through randomising control treatment periods and blind
assessment (Guyatt et al., 1986). Randomisation here means that treatment and control periods do not always occur in the same, or chosen, order. Blind assessment refers to the fact that the person assessing change does not know whether the client was or was not receiving treatment. Aldridge (1994) describes treatment sessions occurring on a weekly basis, once the target behaviour has been identified. However, the number of sessions described in previous single case studies has varied. A study by Pasiali (2004) took place on a daily basis over a four week period, with baseline and treatment alternating each week, while Lett (1993) utilised single case design in an arts-based project in weekly sessions over a 10-week period.
Single case research designs fall under a variety of formality and experimentation. For example, three approaches are: randomised single-case study designs (Guyatt et al., 1986); single-case experimental designs (Smith, 2012); and case study research (Yin, 2009), which may include diary or calendar methods and traditionally includes qualitative data. This may be the preferred approach for studies within the present research, as it looks at changes in a number of variables over time.
Described as a good approach for the beginning researcher, a common feature of single case research is that it stays close to the practice of the therapist, thus
facilitating its design around them. Additionally, autistic clients can be researchers too - Putnam and Chong (2008) suggest this is ideal to counteract the lack of input of users with ASC as recognised in literature. Treatments are discussed between the therapist and client for maximum effectiveness and can be further developed during sessions.
The weakness of single case design is that it is difficult to argue for general validity of the treatment. Marwick (1996) noted that it was easier to generalise the results of a study with more than one participant, compared to a case study report, regardless of the detail that could be gathered. However, Hilliard (1993) argued that replication on a case by case basis counteracted this issue. A formal level of research design could be applied to turn a case study into a case history. According to Accordino et al. (2007), music therapists have argued that only case studies are appropriate since the
treatment schedules are individualised for each client. Thus, the same regimen cannot be followed during therapy for several participants in a study. Moreover, Accordino et al. stated all but two of the reports in the meta-analysis were case studies. More recently, a number of case studies are highlighted in a Nordoff Robbins Scotland article, which illustrated how music therapy can help autistic children (McLachlan, 2016).
Overview of the approach:
Step 1: Identify the target behaviour – this is the baseline measure in the initial period of observation ('A' phase). This phase enables a stable pattern of behaviour to emerge. Three observation points are recommended before the intervention phase begins (Barlow & Hersen, 1973).
Step 2: Introduce the intervention (‘B’ phase).
Aldridge stated that case study research is recognised as a qualitative approach,
although quantitative data can be created. There are possibilities for statistical analysis where daily measures can be plotted and traced over time. This can be done by
therapists and by family members. There can be variations in the design – for example, if treatment variables cannot be randomised, single case experimental designs are used, which have been used in arts therapies (Stanley and Miller, 1993). Aldridge (1994) commented this was an improvement in case history design in that it offered comparative data in two clear phases. The design can also be extended with another A phase if need be, although there may be difficulties faced if ending on a ‘no
intervention’ phase. Alternatively, there could therefore be an ‘ABAB’ design where the idea is to keep the phase lengths identical. Common design methods employed
within music therapy and autism studies include withdrawal (ABA), and reversal (BAB) designs (Villafuerte et al., 2012; Carnahan et al., 2009).
A 10-week case study could be seen as a reasonable time period to test a hypothesis. Edgerton’s study (1994a) involved 11 autistic clients who participated in half-hour sessions each week for 10 weeks. For the study, a communicative responses and acts score sheet (CRASS) was created to test the responses of autistic individuals. The score sheet was divided into two sections: musical and non-musical, which was further broken down into communicative responses and communicative acts. Communicative responses were defined as verbal, vocal, gestural or instrumental behaviours (tempo, rhythm, structure/form, pitch, and speech production) influenced by the therapist. Communicative acts were initiated by the client. A basic ABA withdrawal design was employed. Objective methods of control, observation and data reporting were used, including qualitative and quantitative analyses during and following the study by parents, teachers and speech therapists. This study provided clear and consistent results in favour of the use of improvisational music therapy, and backed up the case for single case design methods due to its successful use of a variety of methods.