Implicit learning deficits among adults with developmental dyslexia

Abstract

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.

Deficits in statistical leaning of auditory sequences among adults with dyslexia

“…Namely, individuals with DD as well as TD readers did not exhibit improvement in performance when given explicit information about the statistical nature of the stimuli. This finding is in contrast to the improvement reported in the previous visual AGL study using explicit visual task (Kahta & Schiff, ). The contrasting findings of the two studies suggest that the ability of adults with DD to explicitly compensate for deficits in SL is limited by the modality of the stimuli.…”

“…The aim of the current study was to examine SL processes among adults with DD using A‐AGL. Like the results of the visual AGL task (Kahta & Schiff, ), the results of the current study indicated that individuals with DD are able to extract the underlying regularities of a complex auditory stimuli with less efficiency than the TD counterparts. In addition, performance on the implicit A‐AGL was correlated with reading performance, that is, decoding, accuracy, and fluency.…”

“…The aim of the current study, therefore, was to explore implicit sequential learning using auditory AGL (A‐AGL) that requires extracting underlying regularities from a complex set of stimuli. The current study follows the procedure of a previous visual AGL study conducted by Kahta and Schiff () using A‐AGL. Therefore, the comparison between TD readers and individuals with DD was conducted using two A‐AGL tasks: implicit and explicit.…”

Neurobiological Basis of Language Learning Difficulties

“…These results suggest that paired-associated learning is impaired when it requires learning of a novel sequence of speech sounds – which taxes the procedural system – but that learning of arbitrary associations, which employs declarative learning, is intact. Further evidence that declarative memory is unimpaired comes from a study reporting that, when an implicit AGL task is made explicit, learning differences are no longer seen in a group of adults with dyslexia [28].…”

Physical fitness modulates incidental but not intentional statistical learning of simultaneous auditory sequences during concurrent physical exercise

“…Incidental statistical learning is considered to be a domain-general and implicit learning process innate to humans, regardless of learner's ages [1,2], suggesting that we might constantly and unconsciously perform statistical learning of sequential stimuli such as language and music [34,35]. Some researchers reported that dyslexia is difficult to perform statistical learning compared to healthy learners [36,37]. Improvement in physical fitness might be useful as clinical application for rehabilitation of language learning in dyslexia.…”