Abstract
Art and art therapy open up interesting possibilities for dementia patients. However, it has not been evaluated scientifically so far, whether the art of sculpting has any benefits.
In this non-randomized pilot study with twelve participants, we investigated the feasibility and acceptance of sculptural activity in patients with dementia and the effects on their well-being.
A questionnaire was custom-designed to investigate five key aspects of well-being: mental state and concentration, corporeal memory, self-reliance, self-esteem and physicality. Remarkable improvements were seen in several subscales in the sculptural activity group, but not the control group: Mental state and concentration (nine of thirteen key aspects), self-reliance (four of five), self-esteem (one of one) and physicality (two of two).
The results of this pilot study indicate the multidimensional effects of sculptural activity on patients living with dementia. The field would benefit greatly from further research.
Keywords: Psychology, Psychiatry, Art, Nursing
1. Introduction
The daily life of dementia patients in nursing homes traditionally includes activities of motoric (sporting), domestic (cooking), cognitive (memory training) and spiritual (religious rituals) nature (Eichenseer and Gräßel, 2011; Maier, 2014). Artistic work with dementia patients is not widely practiced and mainly concentrates on the fields of painting, collage and the receptive art therapy of contemplating images in museums such as the Museum of Modern Art (Chancellor et al., 2014; Tesky et al., 2015). Patients in nursing homes are rarely offered the chance to create sculptural works themselves.
Empirical reports repeatedly stress the fact that people living with Alzheimer's disease are able to work artistically and through their work, experience periods of contentment. This is true for trained artists, such as Carolus Horn (1921–1992), Willem de Kooning (1904–1997) and Hilda Goldblatt Gorenstein (1905–1998) as well as amateurs (Wichelhaus 2002; Ganß, 2013).
In a review published in the Journal of Alzheimer's Disease, Chancellor et al. (2014) present a comprehensive list of qualitative and quantitative art therapeutic studies, including three randomized studies with a small number of participants (Chancellor et al., 2014) on the effectiveness of art therapy in persons living with dementia.
The pilot study presented in this paper aimed at gathering initial data on the effectiveness of sculpting in male dementia patients.
The sculpting of human-sized tree trunks involves a playful approach to the material. Strength and rhythm are required, allowing the experience of corporality, space and orientation. An upright posture must be maintained. The creation of figures that exhibit a resemblance to humans can increase personal awareness, identification with oneself and relations with others, intensified by group interactions amidst the sensory stimulation of the outdoor world.
The tailored questionnaire focused on the areas of well-being attention and flow. The following criteria are of significance (Csikszentmihalyi, 1992; Menzen, 2004; Wichelhaus, 2002):
Sensation of happiness, sadness, joy, sensation of loneliness, courage, relaxation, annoyance, concentration, attention, play, interest, relatedness, communication.
The corporeal memory, also known as ‘implicit memory', stores the sequence of movements and actions that the body has learned over its lifetime, to be carried out automatically if needed. The corporeal memory “re-stages what has been learned in a physical implementation” (Fuchs, 2010).
A patient's personal biography remains present in his visual, audio, haptic and olfactory perception and in the handling of objects (Fuchs, 2010). The reactivation of the corporeal memory can also form a doorway to the explicit memory. The implicit memory remains available significantly longer than the explicit memory in patients living with dementia (see Fig. 1, Fig. 2).
The following questions were raised in the area of corporeal memory:
Did you use to work with wood, sing, paint or play board games? Can you remember your earlier life and, if so, which aspects?
In the areas of self-reliance and self-reference, the following questions were asked:
Do you have the feeling that you have created something?
Do you feel a connection to your creative work?
Answers were rated on an analog scale from 1 to 8 where 1 was “not at all” and 8 was “very much so”.
2. Theory/calculation
Excel 2011, SPSS 22 and Stata 13.1 software were used for the statistical analysis. Simple t-tests were always verified through the non-parametric U-test (linked and unlinked).
The thirteen-week course was evaluated using panel data from three weekly checkpoints: the day preceding the project (0), the day of the project (1) and the day following the project (2).
A linear model with cluster correction (by participants and week) was chosen to avoid pseudo-replication. According to research in the Base Research Manual, cluster correction is necessary to allow for intragroup correlation and the ‘robust' option to correct some kinds of misspecification (Stata13.1, 2013).
3. Hypothesis
Our main hypothesis was that sculpting activity improves mental attributes such as mental state, attention, flow and self-reliance as well as corporeal memory and the patients’ appreciation of their creative work (Dannecker, 2006; Menzen, 2004).
The secondary objective was to investigate to what extent sculpting has an influence on cognitive performance and psychiatric symptoms, measured the Mini-Mental-Status-Examination (MMSE) (Folstein et al., 1975) and the Neuro-Psychiatric Inventory (NPI) (Cummings, 1994), respectively.
4. Method
4.1. Experimental design
A non-randomized study with twelve participants, six in the sculptural activity group and six in the control group, was carried out. Consent to participate in the study and in the assigned group was obtainedfrom the custodian.
4.2. Research participants
All participants had been diagnosed with dementia according to DSM-IVR criteria. A homogenous etiology of dementia was not considered critical because we did not expect dementia subtype-specific effects of the intervention. Dementia severity ranged from 0 to 18 (measured with MMSE). The selection and inclusion of the participants was carried out by nursing staff. The subjects’ decisions to participate in the activities were voluntary and written consent from the subject's custodians was required.
4.3. Sample characteristics
The participants were all retired and lived in nursing homes. Professional qualifications could be determined for eleven of the twelve participants; two (16%) were without professional qualifications; four (33%) had worked as workmen, mechanics or craftsmen; five (41%) had worked in administrative roles, as teachers at vocational colleges or had been soldiers; none had completed a university degree.
One participant in the control group was diagnosed with dementia and chronic schizophrenia. One person in the sculptural activity group was diagnosed with dementia and oligophrenia. One participant from each group passed away during the course of the project. Therefore, five participants per group were evaluated by MMSE and NPI to measure changes.
4.4. Sculptural activity
The sculptural activity took place once a week (for two hours) over a thirteen-week period. A professional sculptor formed pre-selected wood blocks into rough figures for the participants to work on. The outlines of the figures needed to be vague enough to stimulate the creativity of the non-artists without overstraining their imagination. These preparations guided the participants while giving them the illusion of a free hand.
Activities of the control group consisted of painting, singing and playing board games.
4.5. Scales
Potential changes in the cognitive state and psychiatric symptoms of the patients over the course of the project were measured by means of the Mini-Mental-Status-Examination (Folstein et al., 1975) and the Neuro-Psychiatric Inventory (Cummings, 1994). Information pertaining to the specific parameters of the project was gathered via tailored questionnaires in a pre- versus post-activity test one day before and one day after the sculpting project.
The questionnaire was developed to gather information whether the main hypothesis defined in the introduction was valid. The following mental components were operationalized with several sub-questions rated on an eight-point Likert scale (Reips and Funke, 2008; Uebersax, 2006): Mental state, concentration and flow, corporeal memory, self-reliance, self-reference, esteem, facial expressions and physicality.
In order to evaluate test quality criteria, 38 participants with different psychiatric diagnoses completed our self-developed questionnaire at the same time (around 8:00 p.m.) on two days. The participants consisted of nineteen women and nineteen men between the ages of 23 and 85. Test-retest reliability was employed and the data was evaluated using Excel and Stata. The results vary from .280 with feelings of happiness to .877 with memories of wood work.
The values of the multi-variant regression were approximately equally good. They changed only in the category of the weather condition from .05 to .1397 (see Table 1).
Table 1.
Equation | Obs | Parms | RMSE | “R-sq” | F | p |
---|---|---|---|---|---|---|
Mental State of Concentration | ||||||
Feeling of happiness | 99 | 4 | 1.605195 | 0.1731 | 6.628558 | 0.0004 |
Sad | 99 | 4 | 1.101643 | 0.0838 | 2.896232 | 0.0392 |
Glad | 99 | 4 | 1.4179 | 0.2917 | 13.03937 | 0.0000 |
Lonely | 99 | 4 | 1.092319 | 0.1129 | 4.030635 | 0.0096 |
Brave | 99 | 4 | 1.540693 | 0.4278 | 23.67242 | 0.0000 |
Relaxed | 99 | 4 | 2.164686 | 0.2029 | 8.058788 | 0.0001 |
Annoyed | 99 | 4 | 1.067238 | 0.0554 | 1.855659 | 0.1424 |
Concentrated | 99 | 4 | 1.985705 | 0.3265 | 15.35152 | 0.0000 |
Attentive | 99 | 4 | 1.943016 | 0.2959 | 13.31102 | 0.0000 |
Playful | 99 | 4 | 0.9709387 | 0.0129 | 0.4132286 | 0.7439 |
Interested | 99 | 4 | 1.94402 | 0.3409 | 16.37926 | 0.0000 |
Connected to other people | 99 | 4 | 2.107792 | 0.2516 | 10.6461 | 0.0000 |
Communicative | 99 | 4 | 2.13729 | 0.3139 | 14.49095 | 0.0000 |
Corporeal Memory | ||||||
Used to work with wood | 99 | 4 | 2.13028 | 0.1381 | 50.72826 | 0.0027 |
Used to paint | 99 | 4 | 1.789566 | 0.1266 | 4.588158 | 0.0048 |
Used to sing | 99 | 4 | 2.46882 | 0.1229 | 4.438021 | 0.0058 |
Used to play board games | 99 | 4 | 2.382539 | 0.2039 | 8.10868 | 0.0001 |
General remembering | 99 | 4 | 2.409203 | 0.2506 | 10.59186 | 0.0000 |
Self-reliance | ||||||
Achieved something on his own | 99 | 4 | 1.807242 | 0.3492 | 16.98915 | 0.0000 |
Felt connected with his work | 99 | 4 | 1.703778 | 0.4883 | 30.21587 | 0.0000 |
Self-esteem | 99 | 4 | 1.777014 | 0.4537 | 26.30361 | 0.0000 |
Physicality | ||||||
Happy facial expression | 99 | 4 | 1.707715 | 0.3418 | 16.44343 | 0.0000 |
Upright posture | 99 | 4 | 2.017513 | 0.3049 | 13.89223 | 0.0000 |
Influence of the weather | 99 | 4 | 0.7327424 | 0.0558 | 1.870961 | 0.1397 |
4.6. Evaluation of the secondary target criteria
The sculptural activity group and the control group did not differ significantly in their MMSE-performance prior to the sculptural project (t-test: p = .1223; U-test: p = .0776) (see Table 2, Table 3) There was no significant difference in the change rate post- versus pre-sculptural project.
Table 2.
Group | Number (n) | Minimum (Min) | Maximum (Max) | Median (Med) | Mean (M) | Standard Deviation. (SD) |
---|---|---|---|---|---|---|
Therapy | 6 | 1 | 14 | 9 | 8.2 | 4.6 |
Control | 6 | 3 | 18 | 14 | 13.2 | 5.6 |
Total | 12 | 1 | 18 | 11.5 | 10.7 | 5.5 |
Table 3.
Group | Number (n) | Minimum (Min) | Maximum (Max) | Median (Med) | Mean (M) | Standard Deviation. (SD) |
---|---|---|---|---|---|---|
Therapy | 5* | −4 | 3 | −2 | −1.2 | 2.8 |
Control | 5* | −12 | 0 | −2 | −3.4 | 5.0 |
Total | 10 | −12 | 3 | −2 | −2.3 | 4.0 |
* Two test subjects (one from each group) passed away during the course of the project.
Overall, there were no statistically significant changes in MMSE.
In the control group: (verb. t-test: p = .2016; verb. U-test: p = .0897)
No statistically significant difference could be detected for the MMSE stored values. (t-test: p = .1223; U-test: p = .0776).
In the sculptural activity group: (verb. t-test: p = .3883; verb. U-test: p = .3386)
Amongst the patients collectively: (verb. t-test: p = .1004; verb. U-test: p = .0683),
Between the groups: (t-test: p = .4133; U-test: p = .7496).
No significant difference could be detected for the NPI pre-project stored values. (t-test: p = .5110; U-test: p = .5144); there was no difference in the change rate (post-sculptural activity vs. pre-sculptural activity) (see Table 4, Table 5).
Table 4.
Group | Number (n) | Minimum (Min) | Maximum (Max) | Median (Med) | Mean (M) | Standard Deviation (SD) |
---|---|---|---|---|---|---|
Therapy | 6 | 4 | 30 | 5.5 | 12.2 | 11.7 |
Control | 6 | 2 | 17 | 7 | 8.5 | 6.1 |
Total | 12 | 2 | 30 | 5.5 | 10.3 | 9.1 |
Table 5.
Group | Number (n) | Minimum (Min) | Maximum (Max) | Median (Med) | Mean (M) | Standard Deviation (SD) |
---|---|---|---|---|---|---|
Therapy | 5* | −24 | 1 | −3 | −7.0 | 9.8 |
Control | 5* | −14 | 11 | −1 | −1.4 | 8.9 |
Total | 10 | −24 | 11 | −3 | −4.2 | 9.3 |
*Two test subjects (one from each group) passed away during the course of the project.
Overall, there were no statistically relevant changes in the NPI.
No significant difference could be detected for the NPI pre-project stored values. (t-test: p = .5110; U-test: p = .5144); there is no difference in the change rate (post-sculptural activity vs. pre-sculptural activity).
In the control group: (verb. t-test: p = .7429; verb. U-test: p = .4142),
In the sculptural activity group: (verb. t-test: p = .1863; verb. U-test: p = .0782),
Amongst the patients collectively: (verb. t-test: p = .1878; verb. U-test: p = .0911),
Between the groups: (t-test: p = .3726; U-test: p = .3413).
No group showed a statistically significant change in the NPI.
Two participants (one from each group) passed away during the course of the project.
4.7. Ethical approval
Trial registration: “Bildhauerei mit dementiell erkrankten Männern im Altenheim”, No. 131/151 of Ethik-Kommission, University of Bonn, 06.06.2015.
5. Discussion
5.1. Evaluation of the sculptural activity effects on the informal questionnaire: changes project day versus preceding day
The positive changes experienced in the sculptural activity group were significantly higher than in the control group. Negative changes in the sculptural activity group (sad, lonely, annoyed, playful, and weather conditions) applied equally to those of the control group and were, with one exception, insignificant. The exception was the influence of the weather, which played an important role for the sculptural activity group working outdoors. This was mirrored in the borderline value of p = .050 (see Table 6).
Table 6.
Variable | Average Change Within the Group |
Therapeutic Effect | p | |
---|---|---|---|---|
Therapy | Control | Therapy-Control | ||
Mental State and Concentration | ||||
Feelings of happiness | 1.26 | −0.16 | 1.4 | 0.000 |
Sad | −0.08 | −0.02 | −0.1 | 0.797 |
Glad | 1.41 | −0.03 | 1.4 | 0.000 |
Lonely | −0.10 | −0.52 | 0.4 | 0.158 |
Brave | 2.04 | −0.40 | 2.5 | 0.000 |
Relaxed | 0.90 | −0.05 | 1.0 | 0.030 |
Annoyed | −0.15 | −0.26 | 0.1 | 0.713 |
Concentrated | 2.14 | −0.10 | 2.2 | 0.000 |
Attentive | 2.05 | −0.03 | 2.1 | 0.000 |
Playful | −0.19 | −0.35 | 0.2 | 0.556 |
Interested | 2.25 | −0.24 | 2.5 | 0.000 |
Connected to other people | 2.21 | −0.27 | 2.5 | 0.000 |
Communicative | 1.73 | −0.49 | 2.2 | 0.000 |
Corporeal Memory | ||||
Used to work with wood | 1.70 | 0.21 | 1.5 | 0.001 |
Used to paint | 0.29 | 0.42 | −0.1 | 0.733 |
Used to sing | 0.84 | −0.02 | 0.9 | 0.056 |
Used to play board games | 1.75 | −0.77 | 2.5 | 0.000 |
General remembering | 2.48 | −0.67 | 3.2 | 0.000 |
Self-reliance | ||||
Achieved something on his own | 2.15 | −0.38 | 2.5 | 0.000 |
Felt connected with his work | 2.45 | −0.04 | 2.5 | 0.000 |
Self-esteem | 2.64 | −0.07 | 2.7 | 0.000 |
Physicality | ||||
Happy facial expression | 1.95 | −0.25 | 2.2 | 0.000 |
Upright posture | 2.04 | −0.18 | 2.2 | 0.000 |
Influence of the weather | −0.46 | −0.20 | −0.26 | 0.050 |
The informal questionnaire to test the base hypothesis (see Table 1) was double-checked against 38 patients without neuro-degenerative disorder and acute psychiatric illness to establish whether the indications of psychological components (mental state/attention, corporeal memory, autarchy, self-worth) and physicality were present on two consecutive days.
5.2. Analysis of process (an example)
On the chart the average changes in each group over time (days) are depicted.
Examplary reading: (see Fig. 1) In the first week, the therapy group had a score of 2.5, i. e. an average of 2.5 more points on the project day than on the preceding day. Therefore, the short-term therapeutic effect on the project day – compared with the preceding day – was 2.5, whereas in the second week there was no short-term therapeutic effect.
Except for the sixth week, values for the therapy group remained positive for the duration of the project and saw an upward trend towards its conclusion. In other words, there was a continuous improvement in comparison with the day preceding the project. Changes in the control group arose from the growing or waning interest of the test subjects in comparison with the day preceding the project.
Examplary reading: (see Fig. 2) In the first week, the therapy group had a score of 2, i. e. an average of 2 more points on the project day than the preceding day.
While the values of the test subject in the sculpting group were continuously positive, the values of the control group oscillated between 1.5 and −4, showing that the test subjects in the sculpting group remembered more.
5.3. Limitations
This study aimed at assessing the feasibility and acceptance of sculptural activities in dementia patients. Furthermore, we wanted to provide a preliminary demonstration of their effects on several aspects of well-being. The small number of patients and the cluster-randomized design clearly limits the interpretation of the observed effects of the activity. Other limitations of our study include the heterogeneity of the patients with regard to the dementia cause and the non-standardization of the control conditions. Larger, preferably randomized trials with a well-defined control conditions are thus needed to substantiate the findings of the effects of sculptural activity in dementia patients.
6. Conclusions
The pilot study with a small sample size and a non-randomized design answered the following research questions.
The well-being of male patients living with dementia can be influenced positively through supervised sculpting activities. Specific artistic/art-therapeutic criteria closely connected to parameters such as mental state, attention, corporeal memory, self-reliance, self-esteem and physicality are measurable though external assessment for up to six hours after the activity (see Table 1).
Significant results were obtained in nine of the thirteen categories pertaining to emotional well-being and attention, in four of the five categories pertaining to corporeal memory and in all the relevant categories pertaining to self-reliance, self-esteem and physicality.
Sculpting itself is an ancient art. Wood was used as the medium through which the participants in this project were able to experience sensory and aesthetic sensations. These in turn can activate creative potential and buried emotional and cognitive resources (Seifert, 2013).
Aesthetic objects are life-affirming, meaningful and constructive (Schurian, 1986). Aesthetic and artistic processes influence mental well-being, attention and flow, contributing to satisfaction and happiness (Allesch and Korenjak, 2009). Moreover, the task, material and tools can form a concrete reference to aspects of the patients’ former lives, such as work and hobbies.
Further studies should be undertaken in order to corroborate the results presented here.
Declarations
Author contribution statement
Kathrin Seifert: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data; Wrote the paper.
Klaus Fliessbach: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data; Contributed reagents, materials, analysis tools or data.
Annika Spottke: Conceived and designed the experiments; Performed the experiments; Analyzed and interpreted the data.
Competing interest statement
The authors declare no conflict of interest.
Funding statement
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Additional information
No additional information is available for this paper.
Acknowledgments
My special thanks go to Guido Lüchters, Zef/Center of Development Research University of Bonn.
References
- Allesch C.G., Korenjak A. Ästhetische Erfahrung und seelische Gesundheit – Ein Beitrag aus historischer, interkultureller und polyästhetischer Perspektive. [Aesthetic Experience and Mental Health – A Contribution from a Historical, Intercultural and Polyaesthetic Perspective] In: Franzen G., editor. Kunst und Seelische Gesundheit. Medizinisch Wissenschaftliche Verlagsgesellschaft; Berlin: 2009. pp. 31–46. ISBN: 978-3·939069·96-6. [Google Scholar]
- Csikszentmihalyi M. 2nd ed. Klett-Cotta; Stuttgart: 1992. Flow. Das Geheimnis des Glücks. [Flow. The Secret of Happiness] ISBN: 978-3-608-96148-5. [Google Scholar]
- Chancellor B., Duncan A., Chatterjee A. Art therapy for Alzheimeŕs disease and other dementias. J. Alzheimeŕs Dis. 2014;39:1–11. doi: 10.3233/JAD-131295. [DOI] [PubMed] [Google Scholar]
- Cummings J.L. UCLA School of Medicine, Reed Neurological Research Center; Los Angeles, CA: 1994. Neuropsychiatric Inventory – Comprehensive Assessment of Psychopathology in Patients with Dementia. [Google Scholar]
- Dannecker K. Medizinisch Wissenschaftliche Verlagsgesellschaft; Berlin: 2006. Psyche und Ästhetik Die Transformationen der Kunsttherapie. [Psyche and Aesthetics. The Transformations of Art Therapy] 10:3-939069-00-0. [Google Scholar]
- Eichenseer B., Gräßel E. Elsevier; München: 2011. Aktivierungstherapie für Menschen mit Demenz. Motorisch, alltagspraktisch – kognitiv – spirituell. [Activation Therapy for People with Dementia. Motoric, Everyday – Cognitive – Spiritual] ISBN: 978-3-437-28021-4. [Google Scholar]
- Folstein M.F., Folstein S.E., McHugh P.R. Mini-Mental State (a practical method for grading the state of patients for the clinician) J. Psychiatr. Res. 1975;12:189–198. doi: 10.1016/0022-3956(75)90026-6. [DOI] [PubMed] [Google Scholar]
- Fuchs T. 2010. Das Leibgedächtnis in der Demenz [The Body Memory in Dementia] http://www.jungekirche.de/2010/310/leibgedaechtnis.html (02.03.2015) [Google Scholar]
- Ganß M. Mabuse; Frankfurt: 2013. Demenz-Kunst und Kunsttherapie. Künstlerisches Gestalten zwischen Genuss und Defizit. 2. ed. [Dementia Art and Art Therapy. Artistic Design Between Pleasure and Deficit] 978-3-940529-50-3. [Google Scholar]
- Maier W. Herausforderungen durch den demographischen Wandel Psychische Erkrankungen heute und morgen. [Challenges through the demographic change. Mental diseases today and tomorrow] Nervenarzt. 2014;85:1343–1344. doi: 10.1007/s00115-014-4029-3. [DOI] [PubMed] [Google Scholar]
- Menzen K.H. Reinhardt; München: 2004. Kunsttherapie mit altersverwirrten Menschen [Art Therapy with People Confused by Age] ISBN-10 3497017027. [Google Scholar]
- Reips U.D., Funke F. Interval-level measurement with visual analogue scales in Internet-based research: VAS Generator. Behav. Res. Methods. 2008;40:699–704. doi: 10.3758/brm.40.3.699. [DOI] [PubMed] [Google Scholar]
- Schurian W. Westdeutscher Verlag; Opladen: 1986. Psychologie ästhetischer Wahrnehmungen. Selbstorganisation und Vielschichtigkeit von Empfindunge. Verhalten und Verlangen. [Psychology of Aesthetic Perceptions. Self-organization and Complexity of Feelings, Behaviour and Desire] [Google Scholar]
- Seifert K. Claus Richter; Köln: 2013. Kunsttherapie bei Patienten mit unipolaren Depressionen im klinischen Bereich. Entwicklun. Durchführung und Evaluation eines fototherapeutischen Behandlungsmodells. [Art Therapy in Patients with Unipolar Depression in the Clinical Area. Development, Implementation and Evaluation of a Phototherapeutic Treatment Model] [Google Scholar]
- Stata13.1 . Stata CorpLP; College Station, USA: 2013. Base Reference Manual; pp. 2454–2455. [Google Scholar]
- Tesky V.A., Schall A., Pantel J. Kunsttherapeutische Ansätze bei Menschen mit Demenz Übersicht zum aktuellen Forschungsstand und Ausblick. [Art Therapeutic Approaches in People with Dementia. Overview of Current Research and Outlook] Zeitschrift für Musik-, Tanz und Kunsttherapie. 2015;26:79–87. [Google Scholar]
- Uebersax J.S. 2006. Likert Skalen: Aufräumen der Verwirrung. [Likert Scales: Tidying up the Confusion] http://www.john-uebersax.com/stat/likert.htm (04.03.2015) [Google Scholar]
- Wichelhaus B. Das Oeuvre von Carolus Horn aus künstlerischer und kunsttherapeutischer Perspektive – ‘ein Alzheimerpatient macht Karriere'. [The oeuvre of Carolus Horn from an artistic and art-therapeutic perspective – ‘a patient of Alzheimer‘s disease makes a career'] limited edition. Zeitschrift für Musik-, Tanz und Kunsttherapie. 2002;13:123–128. [Google Scholar]