Participants: Participants of our study (N=15) were randomly chosen individuals from all parts of Hungary from all socio-economic backgrounds. They had very different age (from 2;8 to 14;8). They had mild (n=5) to moderate (n=10) intellectual developmental disorder with very different etiology (genetic syndromes, cerebral paresis, perinatal brain injury and/or metabolic diseases) and presented heterogenious comorbid phenomena (e.g. obsessive behaviour, severe ADHD and/or motoric dysfunctioning /dyspraxia, ataxia and hemiphlegia/. Two children were diagnosed with ASD. All of them had problems with speech comprehension and expressive language. Four of them were non-verbal children upon arrival.

Intervention: FIE-Basic and MST (Mediated Self-talk) within the framework of Mediated Learning Experience as for way of interaction. The time of acceleration was 24 months in each cases. The intervention sessions were one-to-one with large intensity (7-15 sessions per week).

Methodology: The first part of the empirical research desribes the development of the individual cases (qualitative method of multiple embedded case studies), and the second part presents aggregated data and test-probes (descriptive statistics and test-statistics).

Main results: Raven Colored Matrices showed an increase in general intelligence of our atypical population by 29,37%p within the two year long intervention period (mean improvement). PPVT has indicated a 3 year 10 month growth in mental years within the two year long intervention time as a mean improvement for 14 cases. Analysis by test-statistics (Paired Samples T-test) has indicated that there were significant changes in the cognitive development of the participants between pre-test and post-test measures on Raven’s Colored Matrices (mean 10,57, SD=6,12, t=6,460, p<0,001;). Results gained by a school screening criterion-oriented test system (DIFER-test) have shown a mean growth of improvement by 39,46%p in domains necessary for school readiness. The very intensive human figure development of the participants – as a generalized “byproduct” of the intervention – prove to be surprising.

Conclusions: The boundaries of human intellect can be enlarged in case of intellectual disability as well. It is possible to improve fluid intelligence of children with cognitive impairments, using a comprehensive program such as MLE, FIE-Basic and MST. If applied systematically with children with intellectual disabilities for a longer period of time (maybe even for 3-4 years) the applied systems are expected to lead to increased learning effectiveness, more effective basic cognitive processes and thinking skills, and to prepare children for school learning and a better adaptation to the challenges of everyday life.