Implicit learning in children with spelling disability: evidence from artificial grammar learning

Contribution of orthographic knowledge to reading and spelling in Bosnian highly transparent orthography

The link between orthographic processing skills and reading and spelling abilities has been demonstrated in different studies and languages. However, previous research has not fully clarified this relationship. We examined the relationship between orthographic knowledge and reading and spelling performance in children from the second to the fifth grade of elementary school. We included measures of orthographic knowledge in two scripts (Latin and Cyrillic) for the same language, at both the lexical and sublexical levels. Word-specific orthographic knowledge was assessed by presenting children with pairs of words in which one word followed the orthographic rules of the Bosnian language, while the other was spelled incorrectly. General orthographic knowledge was assessed with an orthographic word-likeness task, where children had to choose the correct pseudoword, which followed legal orthographic patterns, while the incorrect ones did not. Reading and spelling, phonological awareness, and working memory were also included in the research. In Latin, no relationship was found between reading and spelling and orthographic knowledge, independent of the measure of orthographic processing. In Cyrillic, spelling performance predicts progress in general orthographic knowledge. The results of the study suggest that orthographic knowledge does not contribute to reading and spelling between Grades 2 and 3. General orthographic knowledge was an independent predictor of spelling in Grades 4 and 5 for Cyrillic, the second script. The findings suggest that the development of orthographic knowledge should be considered in the context of the specific language, script, and orthography.

Statistical learning in children with a family risk of dyslexia

The assumption that statistical learning is affected in dyslexia has generally been evaluated in children and adults with diagnosed dyslexia, not in pre-literate children with a family risk (FR) of dyslexia. In this study, four-to-five-year-old FR children (n = 25) and No-FR children (n = 33) completed tasks of emerging literacy (phoneme awareness and RAN). They also performed an online non-adjacent dependency learning (NADL) task, based on the Serial Reaction Time (SRT) task paradigm. Children's accuracy (hits), signal sensitivity (d') and reaction times were measured. The FR group performed marginally more poorly on phoneme awareness and significantly more poorly on RAN than the No-FR group. Regarding NADL outcomes, the results were less straightforward: the data suggested successful statistical learning for both groups, as indicated by the hit and reaction time curves found. However, the FR group was less accurate and slower on the task than the No-FR group. Furthermore, unlike the No-FR group, performance in the FR group varied as a function of the specific stimulus presented. Taken together, these findings fail to show a robust difference in statistical learning between children with and without an FR of dyslexia at preschool age, in line with earlier work on older children and adults with dyslexia.

Language-Specific Effects in Response to Spelling Intervention in Italian and in English as an Additional Language

According to a language-integrated view of spelling development, learning to spell involves the same language-learning skills across alphabetic systems. A prediction based on this view is that the same spelling training should be equally effective for learning to spell in a shallow (Italian, native language) or an opaque (English, additional language) orthography. We tested this prediction by teaching 6- to 9-year-old Italian children to use multiletter spelling units to spell words in Italian and English. The children were trained on the spelling of Italian words containing orthographic difficulties that required switching from phoneme-grapheme spelling correspondences to larger grain size (multiletter) spelling units. In a stepped-wedge cluster randomized trial, 108 Italian children (ages 6-9 years) were assigned to the experimental spelling training or a waiting list condition. Their ability to spell the trained (Italian and English) word lists and to generalize the acquired knowledge to new (untrained) words was assessed. Similar learning effects were found in the two languages for the trained word lists. However, generalization of the acquired spelling knowledge to new words occurred only in English. The influence of language-specific factors on learning to spell could account for these findings.

Knowledge of Statistics or Statistical Learning? Readers Prioritize the Statistics of their Native Language Over the Learning of Local Regularities

A large body of evidence suggests that people spontaneously and implicitly learn about regularities present in the visual input. Although theorized as critical for reading, this ability has been demonstrated mostly with pseudo-fonts or highly atypical artificial words. We tested whether local statistical regularities are extracted from materials that more closely resemble one’s native language. In two experiments, Italian speakers saw a set of letter strings modelled on the Italian lexicon and guessed which of these strings were words in a fictitious language and which were foils. Unknown to participants, words could be distinguished from foils based on their average bigram frequency. Surprisingly, in both experiments, we found no evidence that participants relied on this regularity. Instead, lexical decisions were guided by minimal bigram frequency, a cue rooted in participants’ native language. We discuss the implications of these findings for accounts of statistical learning and visual word processing.

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

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.

Developmental Dyslexia, Reading Acquisition, and Statistical Learning: A Sceptic's Guide

Many theories have been put forward that propose that developmental dyslexia is caused by low-level neural, cognitive, or perceptual deficits. For example, statistical learning is a cognitive mechanism that allows the learner to detect a probabilistic pattern in a stream of stimuli and to generalise the knowledge of this pattern to similar stimuli. The link between statistical learning and reading ability is indirect, with intermediate skills, such as knowledge of frequently co-occurring letters, likely being causally dependent on statistical learning skills and, in turn, causing individual variation in reading ability. We discuss theoretical issues regarding what a link between statistical learning and reading ability actually means and review the evidence for such a deficit. We then describe and simulate the "noisy chain hypothesis", where each intermediary link between a proposed cause and the end-state of reading ability reduces the correlation coefficient between the low-level deficit and the end-state outcome of reading. We draw the following conclusions: (1) Empirically, there is evidence for a correlation between statistical learning ability and reading ability, but there is no evidence to suggest that this relationship is causal, (2) theoretically, focussing on a complete causal chain between a distal cause and developmental dyslexia, rather than the two endpoints of the distal cause and reading ability only, is necessary for understanding the underlying processes, (3) statistically, the indirect nature of the link between statistical learning and reading ability means that the magnitude of the correlation is diluted by other influencing variables, yielding most studies to date underpowered, and (4) practically, it is unclear what can be gained from invoking the concept of statistical learning in teaching children to read.

Do children use logic to spell logician? Implicit versus explicit teaching of morphological spelling rules

BACKGROUND

Intervention studies have reported the advantage of teaching children about morphemes for spelling, but direct comparisons between explicit and implicit teaching have been examined systematically in relation to only a few morphological rules.

AIMS

This study compared explicit versus implicit teaching of the functional rule for the conservation of stem morphemes in derived words in English (e.g., logic is conserved in the derivative logician in spite of changes in pronunciation).

SAMPLE

Participants (n = 90; 7- to 9-year-olds) were drawn from three schools with a diverse intake.

METHODS

The design included a pre-test and two post-intervention tests. Participants were randomly assigned to one of three groups: an explicit group, taught about stems and their conservation in derived words; an implicit group, exposed to the same stems and derivatives without explicit teaching; and an unseen control group. At pre- and post-test, the children's spelling of stems in derivatives was assessed. The interventions involved practice games in which the children spelled derived words after seeing the base forms; the explicit group discussed the connection between the spellings, whereas the implicit group did not.

RESULTS

Analyses of variance revealed that explicit teaching led to more significant spelling improvements than implicit or no teaching, and this effect held at both post-tests.

CONCLUSIONS

It was concluded that explicit teaching of the stem conservation rule in derived forms combined with appropriate practice games shows a sustained effect on spelling. The evidence supports explicit teaching of this morphological rule in classroom practice.

Orthographic knowledge predicts reading and spelling skills over and above general intelligence and phonological awareness

It is widely accepted that general intelligence and phonological awareness contribute to children’s acquisition of reading and spelling skills. A further candidate in this regard is orthographic knowledge (i.e., the knowledge about permissible letter patterns). It consists of two components, word-specific (i.e., the knowledge of the spelling of specific words) and general orthographic knowledge (i.e., the knowledge about legal letter patterns of a writing system). Among German students, previous studies have shown that word-specific orthographic knowledge contributes to both reading and spelling. The results regarding general orthographic knowledge and its contribution to reading and spelling are inconsistent. The major goal of the present study was to determine the incremental predictive value of orthographic knowledge for reading and spelling skills among German elementary-school children (N = 66), over and above the contribution of general intelligence and phonological awareness. The second goal was to examine whether there is a difference between the two subtypes of orthographic knowledge in the amount of their respective contribution to reading and spelling performance. The results show that word-specific as well as general orthographic knowledge contribute to both reading and spelling performance, over and above intelligence and phonological awareness. Furthermore, it reveals that both word-specific and general orthographic knowledge explain more variance of spelling compared to reading. Possible explanations for these results, limitations, and implications of the study are being discussed.

Deficits in statistical leaning of auditory sequences among adults with dyslexia

Recently, it has been suggested that developmental dyslexia (DD) is related to deficits in general mechanisms of statistical learning (SL). The aim of the current study was to explore these relations using a nonlinguistic auditory artificial grammar learning (A-AGL) task. Most studies using AGL to explore the role of SL among readers with dyslexia used visual stimuli. The current study explored SL abilities among adults with DD using a nonlinguistic auditory task, because evidence suggests that SL is affected by the modality of stimuli. Forty-eight (21 DD and 27 typically developed [TD]) adults participated in two A-AGL tasks: implicit and explicit. The results showed a significant difference between the groups, as TD readers outperformed adults with DD. This difference in performance supports the SL deficit hypothesis among adults with dyslexia, although the causal relations between auditory SL and reading still require further examination. In addition, no difference was found between the implicit and explicit tasks, suggesting that unlike the visual AGL, participants with DD do not benefit from elevating attentional resources during A-AGL.

Visual artificial grammar learning in dyslexia: A meta-analysis

BACKGROUND

Literacy impairments in dyslexia have been hypothesized to be (partly) due to an implicit learning deficit. However, studies of implicit visual artificial grammar learning (AGL) have often yielded null results.

AIMS

The aim of this study is to weigh the evidence collected thus far by performing a meta-analysis of studies on implicit visual AGL in dyslexia.

METHODS AND PROCEDURES

Thirteen studies were selected through a systematic literature search, representing data from 255 participants with dyslexia and 292 control participants (mean age range: 8.5-36.8 years old).

RESULTS

If the 13 selected studies constitute a random sample, individuals with dyslexia perform worse on average than non-dyslexic individuals (average weighted effect size=0.46, 95% CI [0.14 … 0.77], p=0.008), with a larger effect in children than in adults (p=0.041; average weighted effect sizes 0.71 [sig.] versus 0.16 [non-sig.]). However, the presence of a publication bias indicates the existence of missing studies that may well null the effect.

CONCLUSIONS AND IMPLICATIONS

While the studies under investigation demonstrate that implicit visual AGL is impaired in dyslexia (more so in children than in adults, if in adults at all), the detected publication bias suggests that the effect might in fact be zero.

Effect of chunk strength on the performance of children with developmental dyslexia on artificial grammar learning task may be related to complexity

There's a long held view that chunks play a crucial role in artificial grammar learning performance. We compared chunk strength influences on performance, in high and low topological entropy (a measure of complexity) grammar systems, with dyslexic children, age-matched and reading-level-matched control participants. Findings show that age-matched control participants' performance reflected equivalent influence of chunk strength in the two topological entropy conditions, as typically found in artificial grammar learning experiments. By contrast, dyslexic children and reading-level-matched controls' performance reflected knowledge of chunk strength only under the low topological entropy condition. In the low topological entropy grammar system, they appeared completely unable to utilize chunk strength to make appropriate test item selections. In line with previous research, this study suggests that for typically developing children, it is the chunks that are attended during artificial grammar learning and create a foundation on which implicit associative learning mechanisms operate, and these chunks are unitized to different strengths. However, for children with dyslexia, it is complexity that may influence the subsequent memorability of chunks, independently of their strength.

Statistical learning and dyslexia: a systematic review

The existing literature on developmental dyslexia (hereafter: dyslexia) often focuses on isolating cognitive skills which differ across dyslexic and control participants. Among potential correlates, previous research has studied group differences between dyslexic and control participants in performance on statistical learning tasks. A statistical learning deficit has been proposed to be a potential cause and/or a marker effect for early detection of dyslexia. It is therefore of practical importance to evaluate the evidence for a group difference. From a theoretical perspective, such a group difference would provide information about the causal chain from statistical learning to reading acquisition. We provide a systematic review of the literature on such a group difference. We conclude that there is insufficient high-quality data to draw conclusions about the presence or absence of an effect.

Implicit learning of non-linguistic and linguistic regularities in children with dyslexia

One of the hallmarks of dyslexia is the failure to automatise written patterns despite repeated exposure to print. Although many explanations have been proposed to explain this problem, researchers have recently begun to explore the possibility that an underlying implicit learning deficit may play a role in dyslexia. This hypothesis has been investigated through non-linguistic tasks exploring implicit learning in a general domain. In this study, we examined the abilities of children with dyslexia to implicitly acquire positional regularities embedded in both non-linguistic and linguistic stimuli. In experiment 1, 42 children (21 with dyslexia and 21 typically developing) were exposed to rule-governed shape sequences; whereas in experiment 2, a new group of 42 children were exposed to rule-governed letter strings. Implicit learning was assessed in both experiments via a forced-choice task. Experiments 1 and 2 showed a similar pattern of results. ANOVA analyses revealed no significant differences between the dyslexic and the typically developing group, indicating that children with dyslexia are not impaired in the acquisition of simple positional regularities, regardless of the nature of the stimuli. However, within group t-tests suggested that children from the dyslexic group could not transfer the underlying positional rules to novel instances as efficiently as typically developing children.

Implicit learning deficits among adults with developmental dyslexia

The aim of the present study was to investigate implicit learning processes among adults with developmental dyslexia (DD) using a visual linguistic artificial grammar learning (AGL) task. Specifically, it was designed to explore whether the intact learning reported in previous studies would also occur under conditions including minimal training and instructions that do not reveal the grammatical nature of the strings. Twenty-nine (14 DD and 15 typical development (TD)) adults were presented with letter sequences in the training phase and were asked to classify the test strings for their grammaticality. The results of the d' measures in the implicit task indicated that learning had occurred for both groups, as the proportion of hits exceeded the proportion of false alarms. However, a significant difference was found between the groups in their learning measures, as TD readers performed significantly better than individuals with DD, supporting the assumption of a deficit in implicit sequential learning processes among individuals with DD. In order to examine whether the deficit found in the first experiment was indeed due to a deficit in implicit processes, a second experiment was designed in which explicit instructions were given during an AGL task. Results of the explicit task strengthen the assumption that the deficit is indeed specific to implicit sequential processes, as no difference between the groups was found when participants were aware of the existence of the grammar underlying the strings. Theoretical and clinical implications are discussed.