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Implicit Learning in Specific Developmental Disorders

Final Report Summary - ILSDD (Implicit Learning in Specific Developmental Disorders)

It is widely accepted that people have the ability to learn regularities from their environment without explicit teaching. Implicit statistical learning (or implicit learning) describes this unintentional and largely automatic learning that is implicated in many cognitive functions including that of reading. ‘Implicit Learning in Specific Developmental Disorders (ILSDD)’ is an innovative project, funded by the Marie Sklodowska-Curie 7th Programme for Individuals (FP7/2012-2015) under REA grant agreement N° [301704, to examine implicit learning in children by looking at both behavior and the brain. The project rigorously explored the nature of children’s implicit learning and its relationship with reading; based on the proposal that implicit learning difficulties are a strong candidate for explaining why reading is a challenging task for some children.

Building upon previous work (e.g. Pavlidou et al., 2009; 2010; 2014) suggesting differences in implicit learning performance between poor and good readers, ILSDD examined whether children with reading problems show difficulties in implicit learning. The project used behavioral tasks and neuroimaging methods to examine the interplay between behavior and neurobiology of the brain producing new information that contributes to theories of developmental dyslexia and implicit learning. ILSDD produced the first set of behavioral and neuroimaging data on young children’s implicit learning performance across different modalities (vision, touch and sound). This fundamental data formed the basis for a novel evidence-based interactive digital intervention for poor readers.

During the first 2 years of the project (2013-2014) 50 children between the ages of 6-9 years were recruited. All children participated in a set of behavioral experiments involving visual, auditory and tactile implicit learning tasks as well as in standardized cognitive tests such as IQ and reading measures. Thirty-two children from this cohort (16=good readers; 16=poor readers), sat through a functional Magnetic Resonance Imaging (fMRI) experimental session: functional images of the brain activity during a visual implicit task as well as anatomical, resting state (RS) and diffusion tensor imaging (DTI) scans were acquired from each child.

Results from the behavioral component of the project confirmed key predictions but also added new important data: children with suspicion/ diagnosis of dyslexia (or with pronounced difficulties in reading) showed difficulties in learning, implicitly, complicated patterns: they showed difficulties in extracting the general structure from the items but also in picking up specific item information that could facilitate learning. These difficulties persisted in all of the modalities children were tested on: vision, hearing and touch. Children with good reading skills on the other hand, showed intact implicit learning performance across modalities. Importantly, when looking at how implicit learning skills correlated (or not) with other cognitive measures in good readers, it was found that implicit learning was positively associated with phonological awareness and phonological memory: this finding tentatively suggests that implicit learning may potentially play an important role in facilitating reading-related cognitive processes, which in turn result to effortless and fluent reading.

The novelty of ILSDD research design allowed meaningful inferences to be made about the nature of implicit learning and the resulting knowledge in typical development as well. An open theoretical question with potential practical implications is whether implicit learning is a unitary system/process or not. Notably, ILSDD behavioral results suggest that implicit learning may not be a domain-general mechanism but that is subject to modality constrains: children did not learn the same way across different senses (there was a lack of correlation of performance across modalities). However, additional research is mandatory for the field to reach firm conclusions. Finally, ILSDD experimental design explored the nature of implicit knowledge, in other words, what kind of knowledge children acquire when they perform well in implicit learning tasks? Our findings offer possible constraints for understanding how both modality-specific (encoding visual, auditory or tactile information) and modality-general (extracting structure from visual, auditory and tactile information) computations result in learning. These processes do not seem to be independent (and/ or sequential): there is a potential interplay between implicit knowledge of specific information and information about the structure during learning which is reflected in both general and specific knowledge about the items.

Turning to the neuroimaging component of ILSDD, the first pass of analyses confirms the pattern of behavioral results: children with reading difficulties showed an expected priming effect for structured items, while typically developing children showed increased activation for the same items suggesting creation of new representations (i.e. learning). In other words, good readers showed sensitivity in picking up the structure whereas children with poor reading skills did not show the same sensitivity. Of great interest, the implicit learning paradigm utilized by the project (i.e. the artificial grammar learning task) activated brain regions that are also typically activated during successful reading such as the Inferior Frontal Gyrus (IFG). Additional analysis is currently being performed to explore in more detail the brain-behavior relationships as well as white matter integrity correlates (DTI data) of implicit learning. Updated results will be posted on the project’s website (http://honey-bee.wix.com/ilearn-project) as well as in the scientific papers currently in preparation.

The research questions motivating ILSDD’s ground experimental work led to the development of an intervention study in year 3 (2015) using an evidence-based application [(Implicit Learning Aid for Reading and Numeracy (I-L3a.R.N.)]. The App comes in the form of a fun computer game for iOS portable devices that ILSDD team and external collaborators developed: it is a non-linguistic, culture-free tool that is designed to train the implicit learning system with the potential of improving implicit learning skills and indirectly reading. Forty primary school children (ages 7-9 years) with a diagnosis of developmental dyslexia or reported as having pronounced reading difficulties were recruited. The children were randomly assigned into 2 groups: the intervention group and the control group. All children are given a battery of tests including implicit learning tasks and standardized cognitive measures, including reading measures (pre test). The children who formed the intervention group engage with the application for a week. Immediately after, they are tested again on the same battery of tasks (immediate post-test). Data collection is ongoing and will be completed in the next two months. Updates on the findings of the intervention will be posted on the project’s website (http://honey-bee.wix.com/ilearn-project) as well as in the scientific papers to result. If proven scientifically that this App improves children’s implicit learning and indirectly reading performance, it has the potential to become a useful and fun tool for parents, teachers and above all, children themselves in their struggle with reading.

Overall, ILSDD has produced a high volume of high quality data that are advancing our understanding of how implicit learning functions, its neural signature and the specific relationship this process has with typical and atypical reading. Through scientific and general public dissemination activities and a number of scientific papers in preparation, ILSDD fills a gap in the literature and opens up new avenues for research: its findings hold the promise of become the platform through which we develop and refine successful interventions that could improve the lives of children who continue to struggle in the classroom.