This dissertation is based on results from an intervention study targeting working memory training. A group of 46 boys and 11 girls (aged 10.7) that were attending special units in 16 regular schools participated in the study. The treatment group (n = 42) trained at school every day for 30-40 minutes with an interactive computer program (Cogmed training) for five weeks. The performances of the treatment group on reading related measures and basic number skills are compared to those of a group of students (n =15) that were attending similar special units and received only ordinary special educational instruction. Working memory measures and non-verbal problem solving were compared to students (n = 25) in a control group from a previous study.

In Study I, it was found that reading comprehension and working memory measures correlated and improved at post-tests (T2, T3) for the treatment group to a larger extent than for the comparison group.

In Study II, it was found that working memory measures and basic number skills were highly related. The performance of the boys in the treatment group improved more than that of the boys in the comparison group on basic number test at both post-tests.

In Study III, basic skills assessed three years later (T4) are reported. The treatment group achieved higher scores in reading comprehension compared to pre-tests and compared to the control group.

The treatment group seems to have gained from the cognitive training of working memory with the computer assisted program directly after training, after seven months and at the three year follow-up. The gains were observed on visuo-spatial working memory measure (T2, T3), reading comprehension and on basic number skills in boys (T2, T3, T4).

The possible mechanisms that may be involved in and may explain the observed improvements of performances are discussed: executive function, attention, memory, motivation, emotions. The study has some methodological limitations and more research is needed to substantiate the efficacy of the program.