Unraveling the Interconnections Between Statistical Learning and Dyslexia: A Review of Recent Empirical Studies

Abstract

One important aspect of human cognition involves the learning of structured information encountered in our environment, a phenomenon known as statistical learning. A growing body of research suggests that learning to read print is partially guided by learning the statistical contingencies existing between the letters within a word, and also between the letters and sounds to which the letters refer. Research also suggests that impairments to statistical learning ability may at least partially explain the difficulties experienced by individuals diagnosed with dyslexia. However, the findings regarding impaired learning are not consistent, perhaps partly due to the varied use of methodologies across studies – such as differences in the learning paradigms, stimuli used, and the way that learning is assessed – as well as differences in participant samples such as age and extent of the learning disorder. In this review, we attempt to examine the purported link between statistical learning and dyslexia by assessing a set of the most recent and relevant studies in both adults and children. Based on this review, we conclude that although there is some evidence for a statistical learning impairment in adults with dyslexia, the evidence for an impairment in children is much weaker. We discuss several suggestive trends that emerge from our examination of the research, such as issues related to task heterogeneity, possible age effects, the role of publication bias, and other suggestions for future research such as the use of neural measures and a need to better understand how statistical learning changes across typical development. We conclude that no current theoretical framework of dyslexia fully captures the extant research findings on statistical learning.

Cortical tracking of spoken and written language structures in (dys)fluent readers

“…First, we zoomed into the incremental temporal trajectory of pseudoword learning and found slower establishment of cortical tracking along with poor explicit recognition in dyslexic readers (Chapter 3). This aligns with prior work indicating a domain-general statistical learning difficulty in dyslexia (Schmalz et al, 2017;Singh & Conway, 2021), characterized by reduced sensitivity to various statistical regularities embedded in the language hierarchy, such as phonotactic probabilities (Bonte et al, 2007;Noordenbos et al, 2013) and artificial grammar (Pothos & Kirk, 2004;Van Witteloostuijn, Boersma, Wijnen, & Rispens, 2017), and also those in non-linguistic temporal sequences (Howard, Howard, Japikse, & Eden, 2006;Lum, Ullman, & Conti-Ramsden, 2013). However, research thus far rarely addressed the incremental learning gains and the associated changes in the neural activity while this implicit learning process took place.…”

A meta-analysis on the correlations between statistical learning, language, and reading outcomes.

“…Using the random effects model, the researchers showed that individuals with DD performed significantly worse than TD controls in visual AGL. S. Singh and Conway (2021) carried out a systematic review of SL in dyslexia focusing on studies published after the three meta-analytical reviews (Lum et al, 2013;Schmalz et al, 2017;M. van Witteloostuijn et al, 2017).…”

Reduced Implicit but not Explicit Knowledge of Cross‐Situational Statistical Learning in Developmental Dyslexia

“…Hence, CSSL impairments are likely to contribute to language deficits observed in language disorders (Ahufinger, Guerra, Ferinu, Andreu, & Sanz-Torrent, 2021;McGregor et al, 2022). If SL deficits in DD (Lee et al, 2022;Nicolson & Fawcett, 2019;Singh & Conway, 2021) also extend to the word level, we can expect that TD readers will outperform readers with DD during CSSL. If people with DD have problems in learning cross-situational statistical regularities, we can expect their performance to deteriorate as SL challenges increase.…”

“…Due to its essential role in typical language acquisition, SL has received considerable attention within the field of language disorders, among them developmental dyslexia (DD; for reviews, see Arciuli & Conway, 2018; Lee, Cui, & Tong, 2022; Schmalz, Altoè, & Mulatti, 2017; Singh & Conway, 2021). DD is a developmental language disorder characterized by difficulty in acquiring reading, writing, and spelling skills despite adequate educational opportunities.…”