Previous literature on intellectual disabilities (ID) reveals a consistent lack of focus on reading. In a comprehensive review of literacy skills in this population, Browder and colleagues (2009) showed that previous studies mostly focused on sight words learning rather than on other reading components such as fluency and comprehension. However, recent studies showed that the historic focus on functional reading is too limited in its capacity to exhaustively comprehend different ID learner's needs (Browder et al., 2012). A growing body of literature suggests that people with low IQs, are able to learn reading skills only when appropriate and comprehensive reading instructions are provided for an extended period of time (Allor et al., 2014). Moreover, it has been shown that increased reading abilities in this population are associated to greater postsecondary outcomes, including quality of life, employment, independence. 

The increased interest in understanding how to effectively teach children and adolescents with ID to read has been fueled by increased legislative priorities and societal expectations for individuals in this population. The Convention of the United Nations (2006) has recently stated that participation to social life is a fundamental human right and placed great value on the principle of knowledge accessibility as a key factor for its achievement.

The growing attention on knowledge accessibility for people with ID has led many European countries to establish guidelines for simplifying textual resources (https://easy-to-read.eu/). The available guidelines are mostly used to create product-oriented resources such as digital and analogical contents. The document gives guidance on aspects like: “Do not use difficult words; Always keep your sentences short; Always use a font that is clear and easy to read”.

Comprehensibility, however, is a complex process requiring more than just providing simplified text. The ease-of-comprehending of a text depends on the interplay between readers and content characteristics. Perhaps, the text accessibility cannot be evaluated with just the existing easy-to-read guidelines but requires a research-oriented approach to investigate the process in its complexity (van der Geest & Velleman, 2014).

The aim of this work is to use an evidence-based approach to analyze the impact of a textual simplification process on fluency, comprehension and readiness level of people with intellectual disability.

The study was carried out with a group of 20 participants with intellectual disabilities with a similar level of reading skills. ID subjects were matched to 20 typically developing participants with similar comprehension skills. All participants were tested individually in a quiet room. At the beginning of the experiment, the experimenter explained the procedure in detail from a standard script. Participants were presented with an original and a simplified version of the same text. The simplified version was created accordingly to the easy-to-read guidelines. The presentation order of the two versions was counterbalanced between the participants in each group. After having presented the text, a first legibility judgment was measured by asking participants to express whether they would have been available to read the text (the judgment was expressed using a Likert scale). If the participant was motivated to read, then the parameter of reading fluency was assessed by considering both speed and correctness. At the end of the reading process participants comprehension level was evaluated by administering few basic multiple-choice text-based questions in which the information needed was explicitly available in the text. Finally, a second legibility judgment was measured assessing participants pleasantness in reading. The analysis of the original version of the text showed that some participants with ID manifested a negative first legibility judgment and in few cases the refusal to read. In the control group there was a general judgment of pleasantness and a disposition to read, however few subjects expressed their negative judgment and a scarce availability to read. The analysis of the simplified text showed pleasant judgment and availability to read across all participants in each group. As for the fluency and comprehension level, both parameters were higher in the simplified version compared to the original one for both groups. Between-subjects analysis across ID participants, however, showed a big heterogeneity between participants with diversified levels in both fluency and comprehension skills. Finally, the analysis of the second legibility judgment showed that this parameter was higher in the simplified version for both groups.

Results of the present study showed a general advantage of textual simplification in promoting accessibility to content resources in participants with intellectual disability. The detailed analysis of ID subjects performance revealed a big heterogeneity across participants in fluency and comprehension measures. These results were largely expected since ID refers to a wide range of clinical conditions with diverse etiologies, involving a wide range of cognitive and reading abilities (Carvajal et al., 2012). These results are discussed within the Universal Design for Learning framework (UDL, CAIST, 2011). UDL principles provide a variety of strategies and resources to help meet diverse learning needs and improve accessibility to learning opportunities with the aim of promoting participation and social inclusion. Our results highlight the fact that it is important to include an evidence-based approach into the process of thinking and implementing design for all strategies. An approach focused on the process, rather than on the product of knowledge, may allow a change of perspective: the implicit objective of knowledge accessibility is no longer that of "homogenizing", but it becomes urgent to "diversify", perhaps identifying and understanding a wide range of user needs. Future directions of the present study concern the analysis of different levels of textual simplification (high, medium, low level of simplification) and their impact on fluency, comprehension and readiness skills of people with intellectual disability.

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