Pilot Study
Abilities in action: A pilot study examining cognitive abilities of a neurodiverse individual in music therapy
Jonathan Scheick
Program in Music Education with Specialization In Music Therapy
Department of Music and Performing Arts Professions
Steinhardt Graduate School of Culture, Education and Human Development
New York University
This pilot study explored cognitive abilities in a neurodiverse individual through participation in person-centered music therapy. The purpose was to determine if the research method used in this pilot study would be optimal for a larger study. A pilot study is intended as a small-scale test of the methods and procedures intended to be used in a larger project (Porta, 2008). The method used in this pilot demonstrated how music therapy assisted a nonverbal, neurodiverse individual in accessing cognitive abilities that were not demonstrated outside of the therapeutic environment.
In this study, I maintained dual roles as a researcher and clinician. Accordingly, it was important to engage in reflective practices throughout that addressed the potential effect of this duality upon the study’s outcome. Review of previously-written clinical notes and personal journaling were utilized to collect data and maintain awareness of any conflicts or bias. I felt it was important to continually reflect on both roles as they would impact my interpretive lens when processing data. Clinical note taking was established in my practice before the beginning of this study in order to track client progress and to reflect on the therapeutic process and interactions between client and participant. Session notes were primarily focused on the participant and the person-centered approach to our therapy experience, including specific musical improvisations, interactions and musical responses by the participant.
Journaling as a researcher occurred while reviewing clinical session notes to allow me to approach this process with increased objectivity. I attempted to carry an awareness of how each role could influence the other and the participant. When journaling about my role as a researcher, I sat with the session note, but wrote about my process as a clinician and the internal and external influences, both personal and professional, that were influencing my decision making throughout the therapy session. It was also important to reflect on the influence of my professional past, both as a music therapist and as a psychotherapist in inpatient medical care.
Background
The desire to conduct this study was rooted in observations made over the past ten years of clinical music therapy practice, during which many neurodiverse participants readily displayed a strong neurological connection to music during therapeutic music making. Musical abilities of participants appeared to demonstrate cognitive processes, such as sustained & divided attention, information processing and memory, that were not outwardly evident in the participant’s life outside of his or her music therapy experience. A complementary motivation was to investigate the use of a qualitative research method that allowed the musical experience of a nonverbal, neurodiverse participant to illustrate the occurrence of cognitive abilities in music therapy, while acknowledging the effect of my dual role as a researcher and therapist.
Data collected and utilized from the research participant's music therapy sessions were provided with verbal assent from the participant, and verbal consent from the participant’s mother. Written consent was obtained from the participant’s biological parent, as the participant was unable to do so physically. A pilot study application was submitted to the Internal Review Board of New York University. The IRB granted this study exempt status, due to the use of existing data, specifically previously recorded video of music therapy sessions. I collaborated with Dr. Kenneth Aigen, Music Therapy Program Director at New York University, who acted as principal investigator.
Method
Grounded theory was used as a qualitative research method for this pilot study because of its ability to allow the data to reflect the participant’s experience without preconceived expectations. Grounded theory was selected to allow for data analysis and interpretation that would illuminate the actions of the participant, while allowing for interpretive understandings of the data (Charmaz, 2007). This study’s use of grounded theory as a method of qualitative inquiry is based upon the foundational contributions of Glaser (1978), Strauss and Corbin (1990). It also reflects the advancements in interpretive analysis of Charmaz (2007), Bryant (2002) and Clarke (2005) by using the historical procedures as guidelines while approaching analysis and interpretation with modern methodological assumptions (Charmaz, 2007).
My clinical music therapy framework is founded upon person-centeredness. During the last decade of practice, I have utilized a humanistic, strengths-based approach, influenced largely by the psychological theory of Carl Rogers. In psychotherapy, Rogers emphasized the importance of active listening and genuine empathy, and the corresponding effect these qualities have on the experience of the therapy participant (Rogers, 1961). In music therapy, these attributes, along with patience and rapport building, help foster trust and comfort within therapy sessions and consequently allow therapeutic potential to manifest.
When abilities are overshadowed by disability, therapy participants can struggle to assert their uniqueness and individuality; for some, resulting in internalized comparisons to others instead of bolstering self-confidence. I vividly recall clients who verbalized concerns about their disability, and carried into our sessions a preconceived notion that they were there to fix something wrong. Olivia, a 9–year–old girl who came to music therapy due to a central auditory processing diagnosis, turned to me in our first session and stated “I know there’s something wrong with me...my mom and doctor said so.” Understanding the power of what is said to and around an individual is instrumental in ensuring its impact is not detrimental.
A strengths-based, person-centered experience in music therapy allowed Olivia and other clients to develop a conscious awareness about what they can do. In turn, this bolstered self-esteem and self-confidence in their ability to work with respective developmental or neurological challenge areas.
My music therapy practice was readily influenced by my earlier professional work as a psychotherapist and cognitive rehabilitation therapist. During live, often improvisational music making, I witnessed the natural engagement of participant’s cognitive skills to a degree that often surpassed the engagement of these same skills through traditional therapeutic experiences. For example, music making consistently engaged sustained attention in multiple clients that were previously diagnosed with attention deficit hyperactivity disorder. Despite witnessing these effects of therapeutic music making on cognition firsthand, in preparation for this study, I needed to consider how my clinical background and experience may affect my interpretation of data. For this reason, I felt it was necessary to select grounded theory as a research method, to allow such an occurrence to emerge primarily through the data.
Theoretical Framework
Sara Goering (2015) offered a valuable perspective on disability, specifically the social model of disability, and provided insight into the effect certain models of disability have upon an individual’s existence within society. Goering noted the traditional medical model views disability as an individual problem requiring remediation. In it, the challenges preventing the individual from fully functioning in society are to be scrutinized, with corresponding treatment planning developed to restore normal functioning, or as close to it as can be achieved. It is the disabled individual’s responsibility to adapt and learn to function with his or her disability. This can cause people with disabilities to feel isolated from others and pressured to fit into whatever societal norm has been established or practiced (Goering, 2015). This cause-and-effect relationship was evident in the experience of Brian, a 23-year-old, nonverbal music therapy client, who was the participant in this pilot study.
The social model of disability evolved from the need to distinguish who is responsible for accommodating the differences between individuals and society (Goering, 2015). Anita Silvers (2003) noted that social disability theory recognizes the unique qualities of every individual, and allows society to understand the perceived disability may not be viewed negatively by its possessor. Here, society is responsible for accommodating to the needs of the individual. Through the lens of the social model, core psychological and emotional components of self appear to have greater potential to flourish.
This social model theory aligns with the underlying notions of humanistic music therapy, and its respective theoretical foundations rooted in the work of Abraham Maslow, Carl Rogers and fellow humanistic psychologists. Again, a person-centered model is at the core of my music therapy practice, allowing participants an experience centered upon their strengths and abilities. Randi Rolvsjord (2010) advocated for a strengths-based approach to music therapy through her development of a resource-oriented conceptual framework. In it, she noted that the therapist’s craft exists in equal presence with the client’s craft. Both individuals (the client and therapist) are co-participants on an even playing field (Rolvsjord, 2010).
Positionality & Reflexivity
When I began my clinical experience as a therapist twenty years ago, my work was guided by my desire to care for people as individuals, not as patients, and to ensure that mind, body and spirit were being nurtured. This principle continues to be of utmost importance in my work, rather than the remediation of deficits defined by diagnosis or disability. My vision of person-centered healthcare was increasingly challenged by the policy-driven demands of the medical model many clinicians subscribe to. The dichotomy between my clinical ideals and the reality of our Western healthcare system motivated my transition from hospital-based care into a music therapy private-practice setting.
Reflection on my experience in healthcare prior to private practice music therapy allowed me to better understand the influence of the medical model, over time, on my clinical perspective. In hospital-based care, I was trained to produce session notes that were succinct and challenge-focused, rather than individualized and strengths-based. This approach to note taking manifested from the need to justify reasons for continued care to insurance providers. For example, if I were to write a brief clinical note for Brian using the medical model, it might resemble the following:
“Individual participant (BT) - BT is a 23 yr old, nonverbal male, with pervasive developmental and cognitive challenges, including attention and processing delays.”
This style of note-taking contains an element of clinical detachment, a form of self-preservation in work that is emotionally demanding. However, highlighting one’s diagnosis more than nurturing individual strengths carries detrimental potential for a person such as Brian and to society, as doing so weakens our social contract.
A strengths-focused approach to session notes, guided through the social model, nurtures professional connectivity between the therapist and participants:
“Brian is a twenty-three year old, neurodiverse young man who has a very strong connection to music and has developed an ability to communicate primarily through nonverbal facial expressions, instrumental musical expressions and body language.”
Both the medical model of disability and influential pressures healthcare clinicians face in their respective settings can significantly impact a neurodiverse individual's view of him or herself within society. The social model of disability and humanistic approach to clinical care offer significant potential for neurodiverse individuals to utilize their unique strengths and for society to acknowledge what they can do.
Data Collection
The videotaped sessions utilized in this study were generated during individual music therapy sessions I conducted with Brian while attending the outpatient clinic I operate in New Jersey. Weekly music therapy sessions were approximately forty-five minutes in duration.
The therapy room was organized based upon the evolving relationship that Brian had with instruments of choice. A selection of small percussion and melodic instruments such as guitar, pitched bells, reed horns, tambourine, a cabassa and xylimba were readily accessible. At the center, rear wall of our music room was a white, Yamaha upright, acoustic piano, accessible to both of us. I regularly used an acoustic guitar as my primary instrument. Room dimensions were approximately 12 x 13 feet with an eight-foot ceiling, with walls painted a light sand color. Recording equipment, consisting of a ceiling mounted condenser microphone and video camera with DVD recorder, was located in a niche corner of the room, off to the right side of the piano. It provided an optimal view of the session space and experience, but limited the view to Brian only. By circumstance, I had to position my back to the camera, which restricted the view of the interpersonal, non-verbal communication between us.
Upon the completion of each session, recordings were reviewed, and footage was archived via note taking in the form of indexes. Indexing music therapy session footage was pioneered by Clive Robbins and Paul Nordoff (Nordoff et al.,2007) in their collaboration and foundation of Nordoff-Robbins music therapy, and a process that I was trained to use during my music therapy graduate internship at the Nordoff-Robbins Center for Music Therapy at New York University. Indexing session footage occurred before the initiation of this pilot study, which comprised the existing data. Indexing allowed a unique glimpse into the therapy process, as it often revealed musical and experiential subtleties that were not attended to during the therapy session. As a data collection method, it greatly assisted in maintaining the integrity of the therapy experience.
The indexed sessions were selected based upon initial notes recorded immediately following the completion of a session. These notes specified my observations during particular sessions that acknowledged some increased cognitive engagement. Brian had demonstrated varying levels of cognitive energy and fatigue throughout our therapy. In some sessions, fatigue would lead to disengagement, while in other sessions, Brian would be alert with increased engagement. I selected sessions for data collection in which Brian was more consistently alert and engaged. Specific cognitive skills (beyond increased alertness and engagement) expressed in particular sessions were not previously examined when sessions were selected for analysis.
Data Analysis
Before engaging in the process of data analysis, I felt it was important to consider the evolution of grounded theory methodology, along with the various coding techniques and procedures that can be applied to this study. Acknowledging the substantial contributions of Glaser (1978), Strauss & Corbin (1990), I chose to analyze the data using a procedure practiced by Saldana (2016), which focuses on First Cycle and Second Cycle coding.
According to Saldana, First Cycle coding can incorporate multiple approaches, each with a unique focus or purpose in illuminating the data. He notes that the symbolic construct of a researcher-generated code “translates” data (Vogt, Vogt Gardner, & Haeffele, 2014) and provides interpreted meaning to each datum for later categorization and theory building, capturing the essence of each datum (2016). Selecting specific First Cycle coding methods that could capture the essence of Brian’s music therapy experience was imperative to this analysis, as one of the more challenging aspects of observation and data collection within Brian’s sessions was Brian’s nonverbal status. It is important to acknowledge that inferences were drawn upon observations made, based upon explicit facial gestures and body movement during musical and non-musical dialogue.
The following First Cycle coding methods were carefully selected for the following reasons (Miles, et al.,2020):
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Attribute coding was used to collect essential participant information, especially as it could impact data interpretation and would provide ease of reference in future analysis.
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Descriptive coding was selected to capture data from the physical environment that Brian participated in. This method generated data that spoke to a potential impact of the environment on Brian’s level of engagement and participation.
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Concept coding was implemented to highlight moments within Brian’s experience that were significant beyond surface meaning. This method was especially useful in bridging the gap between an event within a session and my interpretation of that datum as influenced through my training and practice as a cognitive rehabilitation specialist.
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Process coding was selected to highlight the action in the data, specifically musical responsiveness and communication, or action and interaction between participant and therapist.
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Emotion coding was used as emotional experiences that Brian had were his primary method of communication in session, in addition to my inferred reactions.
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Evaluation coding was utilized to assign significance or noteworthiness to datum that was congruent with increased cognitive engagement.
During first cycle coding, the following codes emerged from session indexes after evaluating the session notes line-by-line, while considering the phenomenon of Brian’s increased cognitive engagement during his person-centered music therapy sessions.
First Cycle coding
Attribute codes:
-age, language, challenge, family support, reasons for therapy
Descriptive codes:
-room organization, access to instruments
Process codes:
-taking initiative, maintaining engagement, mutual greetings, expressing opinion, musical selections, nonverbal communication, music accessibility, therapist's preparedness, "goodbye" through music
Emotion codes:
-anxiety, excitement, feeling content, joy
Concept codes:
-Musical awareness, eye contact
Evaluation codes:
-active communication, effect of environment, urgency to play, heightened concentration, purposeful instrument choice, need to transition, from passive to active participation
In order to ensure consistent interpretation of the codes that emerged during the First Cycle analysis, a codebook was created to provide precise meaning to each datum:
1. age (attribute): chronological age of the participant
2. language (attribute): the ability for a participant to verbally communicate (in the English language) as a form of interpersonal communication
3. challenge (attribute): the specific area of difficulty experienced by the participant, in regard to cognitive, physical, psychological / emotional development
4. family support (attribute): direct assistance and support (physical & psychological / emotional) provided by family member(s) to the participant
5. reasons for therapy (attribute): specific areas of focus, within the domains of cognition, physical & psychological / emotional development) that direct the creation of therapeutic goals and objectives
6. room organization (descriptive): the deliberate manner in which the therapist organizes and arranges the physical therapeutic environment
7. access to instruments (descriptive): the physical availability of instruments available to the participant in the therapy room
8. taking initiative (process): the act of leading the direction of the therapy experience
9. maintaining engagement (process): sustaining attention and active participation
10. mutual greetings (process): a therapeutic practice in which the therapist and participant exchange greetings through song / music
11. expressing opinion (process): providing the therapist with information regarding how the participant is feeling and / or what he /she wants to do
12. music selections (process): the active choice of pre-composed, or previously improvised music made by the participant or therapist
13. non-verbal communication (process): the ability to actively communicate feelings desires, needs, emotions through the use of one’s body language and/or a communicative device (devices in session include: dry erase board; computers with text-to-language capabilities)
14. musical accessibility (process): techniques implemented by the music therapist to maximize the music-making experience of the participant (i.e. tuning a guitar to open tuning, to allow the participant to play without knowing hand-chord positions)
15. therapist’s preparedness (process): reference of the therapist’s comprehensive training in music, psychology, human development, and the awareness of the needs of the participant throughout the therapy session.
16. “goodbye” through music (process): a transitional song that facilitates the ending of the therapy session
17. anxiety (emotion): a feeling of apprehension about what is to come
18. excitement (emotion): a feeling of great enthusiasm and eagerness
19. feeling content (evaluation): a sense of satisfaction perceived by the observer
19. joy (emotion): the emotional experience of joy
20. musical awareness (concept): An awareness and understanding of the dynamics of music (i.e. pitch, rhythm, timbre, volume, time) as demonstrated during live, collaborative music making.
21. eye contact (concept): the maintenance of eye gaze on a specific object or individual
22. active communication (evaluation): the act of expressing feelings, desires and / or emotions through verbal or non-verbal methods of communication
23. effect of environment (evaluation): the influence of the physical characteristics of the therapy space on the participant, therapist and / or observer
24. urgency to play (evaluation): a sense of the participant’s desire to play music as a priority
25. heightened concentration (evaluation): increased sustained attention exhibited by the participant
26. purposeful instrument choice (evaluation): deliberate selection of an instrument to use in therapy, based upon its dynamic properties
27. need to transition (evaluation): a sense of urgency perceived by the observer to transition from current task
28. from passive to active participation (evaluation): a notable change / increase in the participant’s physical engagement in music making
After categorically organizing these First Cycle codes, those categorized under process codes appeared to highlight Brian’s increased cognitive engagement and expression of specific abilities that acted as the catalyst of this inquiry. As per family report, Brian’s life outside of his music therapy experience did not actively promote opportunities for social, emotional and cognitive engagement. Interestingly, within the context of our shared experience, the First Cycle data points to initiation, self-expression, decision making, and sustained cognitive energy.
Additional analysis of these codes and their corresponding categories during Second Cycle coding (Saldana, 2016) led to the emergence of several patterns and themes highlighting Brian’s inherent cognitive abilities. These patterns again reflected increased cognitive engagement during music therapy, and included the following codes that reflected Brian’s cognitive skills in action: active communication, expressing opinion, and taking initiative.
Contextually, Brian initiated music therapy when his mother and fellow parents requested starting a small music therapy group, consisting of Brian and two acquaintances. Within the group, I observed that Brian was rarely asked for his insight or opinion regarding music selections by his peer participants. As the therapist, I often engaged Brian directly, asking him for his input. Despite my repeated encouragement, the group dynamic was not conducive to allowing Brian frequent opportunities for self-expression or taking initiative. At times, Brian appeared content allowing others to speak for him, and eventually became less engaged as a group member. When I reflected on this group dynamic, it became evident that Brian’s music therapy group could act as a microcosm of his experience engaging socially and cognitively with the world around him. This prompted my recommendation to transition Brian to individual music therapy sessions, in which I continued to act as his music therapist.
When we began individual music therapy, Brian was very passive in his participation. He did not readily initiate, and was vague in his responsiveness from cues and prompts. Over time, it was evident that Brian’s expressive self was being stifled by societal constraints and limited opportunities to share his unique personality and abilities with the world around him. In his adult life, it was becoming easier for Brian to internally retreat and withdraw when those around him could not or did not take the time to communicate or directly engage him. However, within a supportive, person-centered musical environment, the data collected via First Cycle coding demonstrated how Brian was able to initiate music and instrument selections, and eventually felt comfortable communicating as he was able to, which led to increased self- confidence.
Brian’s level of self-confidence began to correlate with his level of initiation and active communication attempts, as evidenced through the following research journal excerpt:
“After our “Welcome Back To Music” song, Brian actively selected a song to play, gestured to me with purposefully raised eyebrows, and awaited my response. When I acknowledged Brian’s selection, Brian grabbed his guitar and began to strum a count-in to the song.”
Co-occurring emotion codes, such as excitement and joy, along with process codes music selections and non-verbal communication, appear to bolster the significance of taking initiative. The following excerpt from my research journal is exemplary of these co-occurring codes:
“Brian left very little time between song selections, as he immediately picked up the drum stick pointer and gestured to the marker board set list for another song selection. A smile momentarily adorned Brian’s face, after which he rather seriously pondered his next song choice. Brian turned to me again as he pointed to his selection, seeking my agreement. As I quickly repositioned myself, Brian used a rhythmic foot tap to cue me to start the next song.”
Brian recognized and acted upon an opportunity to take leadership initiative in song selection, influencing the direction of this, and future therapy sessions. While grounded theory is not intended for the purpose of generalization of results within the larger population (Miles, et al., 2020), it is intriguing to consider the positive cognitive, emotional and psychological effects that such experiences can have in Brian’s life outside of music therapy.
Discussion
When considering the process codes and evaluation codes that emerged from Brian’s music therapy experience, a hierarchy of cognitive processes became more evident, as compared with the cognitive functioning model developed by Stuss & Benson (1986) in which increased and advanced cognition operates through a trickle up (or down) effect. Lower-level cognitive skills such as arousal and attention have a direct effect on the expression of higher-level cognitive skills, such as information processing, memory and anticipation / planning.
Figure 1:
Title: a hierarchical model of cognitive functioning. Dams-O'Connor, K. & Gordon, W. (2013)
The data collected appears to reflect not only overall increased cognitive engagement, but correlates with Brian’s ability to access and express higher-level cognitive skills once lower-level cognition was engaged and nurtured through music. Specifically, process and evaluation codes including taking initiative, active participation, and heightened concentration appear to have bolstered higher level cognition, as evidenced through purposeful instrument choice, expressing opinion and Brian’s urgency to play.
Furthermore, when considering the effect that music therapy can have in nurturing the emotional and psychological needs of a participant that Maslow described in his hierarchy of needs, such as providing a safe, welcoming environment through which an individual can experience increased esteem, cognitive engagement may be more consistently supported.
Figure 2:
Title: Maslow's psychosocial development: hierarchy of needs model. Maslow, A. (1943)
The use of grounded theory as a research method in this pilot study appeared successful in demonstrating Brian’s cognitive abilities in music therapy, specifically initiation, decision making and active communication, and allowed him, as a nonverbal individual, to have an active voice in the research process. Grounded theory allowed for the organic emergence of these specific cognitive skills engaged and expressed by Brian in session through the First Cycle and Second Cycle coding process (Saldana, 2016) and thematic development throughout data analysis. Consequently, the following assertion emerged from this process, as evidenced through the themes and categories analyzed:
A holistic, person-centered approach to music therapy appears to support a positive correlation between emotional and psychological health and increased access to higher-level cognitive functioning.
Brian’s cognitive abilities in action bolster the social model of disability and its positive attributes (Goering, 2015). When music therapy offers opportunities to engage and express abilities, a participant’s perception of self and society’s perception of the participant can be significantly altered. Expanded analysis of additional participants and data through a larger scale study could provide additional evidence of multiple cognitive skills that are engaged through music therapy.
Data obtained and analyzed through this pilot study led to the emergence of research questions that could be used in such a future, larger-scale investigation:
Primary question: what specific characteristics of person-centered, strengths-based music therapy foster engagement of cognitive skills in neurodiverse participants?
Secondary question: Are particular cognitive skills more readily engaged in this process than others?
A larger study could examine the underlying physiological & neurological mechanisms that are naturally engaged in holistic, person-centered music therapy, along with the expression of respective cognitive skills in study participants. The clinical relevance of understanding how and why music therapy allows for these cognitive skills to become naturally engaged and expressed could provide awareness to family members and support personnel who are unaware of increased cognitive engagement within the therapy session and the corresponding, therapeutic effect on a participant's quality of life.
References
Bryant, A. (2002). Re-grounding grounded theory. Journal of Information Technology Theory and Application, 4(1), 25-42.
Clarke, A. E. (2005). Situational analysis: Grounded theory after the postmodern turn. Sage.
Charmaz, K. (2007). Constructing grounded theory: A practical guide through qualitative analysis. Sage.
Dams-O'Connor, K. & Gordon, W. (2013). Integrating interventions after traumatic brain injury: A synergistic approach to neurorehabilitation. Brain
Impairment, 14(10), 51-62.
Emerson, R. M., Fretz, R. I., & Shaw, L. L. (2014). Writing ethnographic fieldnotes. The University of Chicago Press.
Glaser, B. G. (1978). Theoretical sensitivity: Advances in the methodology of grounded theory. Sociology Press.
Goering S. (2015). Rethinking disability: the social model of disability and chronic dis- ease. Current reviews in musculoskeletal medicine, 8(2), 134–
138.
Miles, M. B., Huberman, A. M., & Saldaña, J. (2020). Qualitative data analysis: A methods sourcebook. SAGE.
Maslow, A. (1943). A theory of human motivation. Psychological Review, 50(4), 370-396.
Nordoff, P., Robbins, C., & Marcus, D. (2007). Creative music therapy: A guide to fostering clinical musicianship. Barcelona.
Palmisano, S., Fasotti, L., & Bertens, D. (2020). Neurobehavioral initiation and motivation problems after acquired brain injury. Frontiers in
neurology, 11(23).
Porta, M. (2008). A dictionary of epidemiology, 5th Edition. Oxford University Press.
Rogers, C. (1961). On becoming a person: a therapist's view of psychotherapy. Houghton Mifflin.
Rolvsjord, R. (2010). Resource-oriented music therapy in mental health care. Barcelona.
Saldana, J. (2016). The coding manual for qualitative researchers, 3rd ed. Sage Publications.
Silvers A. (2003). On the possibility and desirability of constructing a neutral conception of disability. Theor Med. 2003(24),471–87.
Strauss, A. L., & Corbin, J. M. (1990). Basics of qualitative research: Grounded theory procedures and techniques. Sage Publications.
Stuss, D., & Benson, D. (1986). The frontal lobes. Raven Press.
Yalom, I. (2005). The theory and practice of group psychotherapy, 5th edition. Basic Books.
