Many students with intellectual disability experience significant difficulties in assimilating written text through reading and even more struggle with writing. This dissertation aims to investigate whether assistive technologies such as text-to-speech and speech-to-text contribute to providing more opportunities for students with intellectual disability to assimilate and produce text. The first study in the dissertation was a crosssectional study that examined reading and listening comprehension abilities among 70 students with mild or moderate intellectual disability in the age group of 16 to 22 years. The results showed that the students had weak decoding and reading comprehension skills and better listening comprehension. This was particularly evident for students with moderate intellectual disability. In the second study, five fourth-grade students with mild intellectual disability received a decoding intervention. Using a single-subject design, the study demonstrated that all students increased the number of decoded words after the intervention, albeit to varying degrees. For some students, additional decoding training could prove beneficial, while others require alternative approaches. The third study employed a quasi-experimental wait-list control group design involving 41 students with mild or moderate intellectual disability in upper secondary school for pupils with intellectual disability. The purpose was to investigate whether the students further increased their listening comprehension abilities after a period of intervention with text-to-speech. Additionally, there was an interest in monitoring the development of decoding skills during the intervention. The results confirmed that the students assimilated text better through listening and improved even further with listening comprehension training, but no significant differences were found. The students also improved in decoding despite not specifically training for it. The fourth study utilized a single-subject design with four students with mild intellectual disability aged 10 to 14 years. The students were trained to use speech-to-text to produce words and sentences in writing. Three of the students could hardly produce anything in writing via handwriting, while one student could read and write traditionally. However, the results showed that all students increased the number of produced words and sentences and their text quality compared to writing by hand or keyboard. In summary, the results of the four studies demonstrate that many students with intellectual disability have significant difficulties assimilating and producing text through reading and writing traditionally. Most of the students also demonstrated better listening comprehension than reading comprehension. When alternatives such as text-to-speech and speech-to-text were provided, the conditions for understanding the content of written text and the opportunities for producing written text improved. An important conclusion that can be drawn from the studies is also that students with moderate intellectual disabilities may be assumed to face greater difficulties than they actually do if they are only offered traditional reading and writing methods.
