Table 3.

Overview of articles with an indication of active mechanisms of Play Therapy with people with a mild intellectual disability 2008-2020

Author (s)	1. Study design and 2. ccertainty of evidence	Common active mechanisms		Specific active mechanisms
		therapist-client relationship	therapeutic skills
Swan, L.K. and Schottelkorb, A.A. (2014)	1. Single case ABC design. Based on Greenberg's case study method (2007). Two phases: discovery and verification Child with irritability and hyperactive behaviour. The measurement tools: Peabody Picture Vocabulary Test and the Vineland Adaptive Behaviour Scale. 2. Conclusive	safety in the therapeutic presence	ensure a safe and facilitating environment empathy, unconditional acceptance.	non-verbal communication, the process of contact work in CCPT
Swan, K.I. and Ray, D. C. (2015)	1. Case study of two children with irritability and hyperactive behaviour. The measurement tools: Peabody Picture Vocabulary Test and the Vineland Adaptive Behaviour Scale. Single case ABA design. Parents and teachers after the treatment semi-structured interviews. 2. Conclusive	safety in the therapeutic presence	ensure a safe and facilitating environment empathy, unconditional acceptance.
Lorenz D.C. (2010)	1. Literature review keywords: play therapy, child centered play therapy, modifications of play therapy, people with disability. 2. Conclusive	safety in the therapeutic presence	ensure a safe and facilitating environment, empathy, unconditional acceptance.	process-based therapy, non-verbal communication, exploring of feelings and emotions