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Impairments of language development and functional illiteracy

Background and aims

A considerable number of adolescents and adults in Switzerland have insufficient reading skills. Many children do not succeed in realizing their potential in the language area and in acquiring the language skills needed for school success (OECD, 2010).

Several studies have shown that important predictor variables for reading and writing disorders are difficulties in preschool language acquisition and impairments in language development (see Catts et al., 2002; Nash et al., 2013). It would appear that there is an association between language impairments in childhood and insufficient written language skills adulthood (functional illiteracy). As both language impairments and reading and writing disorders persist into adulthood, it is assumed that adults with functional illiteracy can also display anomalies in spoken language.

This cooperation project conducted by the Swiss University for Speech and Language Therapy Rorschach (SHLR), the University of Applied Sciences in Special Needs Education, and the University of Education Weingarten investigated the up-to-now little studied association between language impairments and insufficient written language skills in adulthood (functional illiteracy) by means of an experimental group and control group with a total of 30 participants aged 17 to 60 years. In the main study, there were 20 participants with self-reported difficulties in reading and writing. In the additional study, the same data was collected and compared with a control group of people with comparable age, sex, and educational attainment.


  • Are there associations between spoken and written language skills in people with functional illiteracy in adulthood?
  • Are there language problems also in written language, and are there similar symptoms within the group of participants?
  • Are there problems in metalinguistic skills?
  • Are there similarities in participants’ learning histories?


To assess language and meta-phonology skills we used TROG-D, PHOG, and BAKO1-4 tests and to assess reading and writing we used WLLP-R, SRLT-II, and HSP5-10, employing the paired samples t-test for comparison, assuming that the variances of both groups were not equal. Further, we gained information on personal learning histories. For the qualitative content analysis, we built categories through a combination of deductive and inductive procedures in several work steps (see Mayring, 2010). The evaluation was conducted using the software MAXQDA Plus 2018.

The interviews were also utilized to analyse spontaneous speech in Swiss-German dialect as well as in standard German. For transcription and evaluation of spontaneous speech from the guided interviews, we used the Computerized Language Analysis (CLAN) program from the Child Language Data Exchange System (CHILDES) (see MacWhinney, 2000) in CHAT format.


The experimental group participants’ subjectively perceived impairments in written language were validated via interpretation of the test scores on reading and writing. Their reading and writing skills as assessed by all of the tests were statistically significantly poorer than those of the control group participants.

Altogether, the test results for meta-phonology skills and for the understanding of grammar were also poorer in the experimental group than in the control group. Both groups had more difficulty with the phonology test items than with the test items on morphological/syntactic understanding, for which their scores were average.

This was in line with the evaluations of the three spelling strategies (phonetic, orthographic, morphemic) insofar as in both groups the highest scores were achieved in the use of the morphemic spelling strategy. In contrast, meta-phonology weaknesses appear to be linked with the just below-average scores in the use of phonetic and orthographic spelling strategies, which are important in early acquisition of written language.

The test results on the participants’ spoken language skills provided indications of persisting language acquisition impairments (see Schlamp-Diekmann, 2007), including morphological errors. On some parameters (such as mean length of utterance, sentence complexity) the control group had definitely stronger scores than the experimental group. Due to the sample size, interpretation does not allow generalization of the findings.

The results of the guided interview confirmed in the case of functional illiteracy that there had been difficulties with reading and writing throughout the school years. With comparable educational attainment, 90% of those in the experimental group reported having had problems in school, mainly in language school subjects, whereas 50% of those in the control group mentioned school problems. The descriptions were in line with findings in the international research literature showing that language skills and literacy were reliable predictors of academic achievement especially in language subjects (Durkin et al., 2015; Conti-Ramsden et al., 2009).

Even though most of those in the experimental group had received additional support, as adults they still showed sometimes marked deficits, which they handled in various ways. But it was not possible to overcome or compensate for the existing language impairments through the help of school support measures.

Conclusions for practice

To limit educational disadvantages and to prevent avoidance of the demands of written language also after the school years, support for children and adolescents should encompass both specific special support and appropriate modification of the school learning offerings in language subjects.

Early assessment and support for children with language acquisition difficulties provide a chance to work against the development of reading and writing disorders and the risk of functional illiteracy in adulthood.



Project Management

Schweizer Hochschule für Logopädie Rorschach

Project team


Forschung und Entwicklung
Tel: +41 44 317 11 81

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