Functional illiteracy and developmental dyslexia: looking for common roots. A systematic review

Abstract

A considerable amount of the population in more economically developed countries are functionally illiterate (i.e., low literate). Despite some years of schooling and basic reading skills, these individuals cannot properly read and write and, as a consequence have problems to understand even short texts. An often-discussed approach (Greenberg et al. 1997) assumes weak phonological processing skills coupled with untreated developmental dyslexia as possible causes of functional illiteracy. Although there is some data suggesting commonalities between low literacy and developmental dyslexia, it is still not clear, whether these reflect shared consequences (i.e., cognitive and behavioral profile) or shared causes. The present systematic review aims at exploring the similarities and differences identified in empirical studies investigating both functional illiterate and developmental dyslexic samples. Nine electronic databases were searched in order to identify all quantitative studies published in English or German. Although a broad search strategy and few limitations were applied, only 5 studies have been identified adequate from the resulting 9269 references. The results point to the lack of studies directly comparing functional illiterate with developmental dyslexic samples. Moreover, a huge variance has been identified between the studies in how they approached the concept of functional illiteracy, particularly when it came to critical categories such the applied definition, terminology, criteria for inclusion in the sample, research focus, and outcome measures. The available data highlight the need for more direct comparisons in order to understand what extent functional illiteracy and dyslexia share common characteristics.

Construct validity of international literacy measures: implications for dyslexia across cultures

“…That is, most students are neither dyslexic nor highly advanced; they are, by definition, in the middle of the distribution of all readers. Given this, a potential consideration is to have well-defined criteria of functional illiteracy (Vágvölgyi et al, 2021 ), categorically distinctive from both developmental dyslexia and skilled reading. One might argue that the same measure reporting proficient readers in specific languages and countries is disproportionately detecting poor readers in others.…”

The literate mind

“…Their findings also raise some questions about other reports of cultural effects on visual illusion perception. Vágvölgyi et al, (2021) present a systematic literature review exploring the similarities and differences identified in empirical studies investigating both functional illiterates and people with developmental dyslexia. They find that there is lack of studies directly comparing functional illiterates with people with developmental dyslexia and a huge variance between studies in how they approached the concept of functional illiteracy, particularly concerning the applied definition, terminology, criteria for inclusion in the sample, research focus, and outcome measures.…”