Developmental dyslexia and explicit long‐term memory

Abstract

The reduced verbal long-term memory capacities often reported in dyslexics are generally interpreted as a consequence of their deficit in phonological coding.The present study was aimed at evaluating whether the learning deficit exhibited by dyslexics was restricted only to the verbal component of the long-term memory abilities or also involved visual-object and visual-spatial domain. A further goal of the present study was to investigate the predictive value of non-verbal long-term memory abilities with respect to word and non-word reading in dyslexic children.In accordance with these aims, performances of 60 dyslexic children were compared with that of 65 age-matched normal readers on verbal, visual-spatial and visual-object task.Results documented a generalized impairment of episodic long-term memory capacities in dyslexic children and the results did not vary as a function of children's age.Furthermore, in addition to verbal measures, also individual differences in non-verbal long-term memory tasks turn out to be good predictors of reading difficulties in dyslexics.Our findings indicate that the long-term memory deficit in dyslexia is not limited to the dysfunction of phonological components but also involves visual-object and visual-spatial aspect, thus suggesting that dyslexia is associated to multiple cognitive deficits.

Devil in the details? Developmental dyslexia and visual long-term memory for details

“…For example, Nelson and Warrington (1980) reported normal LTM functions in developmental dyslexia (see also Bell, 1990). In contrast, a recent Italian study reported specific LTM impairments in dyslexics (Menghini et al, 2010; see also Watson and Willows, 1995). Probably, these heterogeneous findings are due to the fact that those studies did not explicitly address resolution issues in LTM, that is, the ability to acquire highly detailed representations of visual objects.…”

“…The core result of our study is that while the overall amount of LTM errors was comparable between groups, dyslexics showed a significantly greater portion of detail-related memory errors, suggesting a specific spatial resolution deficit in VLTM of dyslexic children. Previous studies on the role of VLTM in dyslexia only yielded mixed results (ranging from normal to impaired LTM functions; see Nelson and Warrington, 1980; Bell, 1990; Watson and Willows, 1995; Menghini et al, 2010), probably because these studies did not specifically address the issue of VLTM resolution, which may be of utmost importance regarding the storage of visual word forms in the mental lexicon.…”

The Role of Executive Functions in the Reading Process

“…Previous studies have identifi ed defi cits in a sub-domain of executive functioning in both children and adults with dyslexia (Altemeier, Abbott, & Berninger, 2008 ;Brosnan, Demetre, Hamill, Robson Shepherd et al, 2002 ;Helland & Asbjornsen, 2000 ;Horowitz-Kraus, 2014 ;Gooch, Snowling, & Hulme, 2011 ;Kraus & HorowitzKraus, 2015 ;Menghini, Carlesimo, Marotta, Finzi, & Vicari, 2010, Reiter, Tucha, & Lange, 2005Tiffi n-Richards, Hasselhorn, Woerner, Rothenberger, & Banaschewski, 2008 ). One of the only ERP studies to examine the impairment of EF in individuals with dyslexia (Horowitz-Kraus, 2014 ) used the Wisconsin card-sorting task, which is a task that encompasses several EF domains.…”

Deficits in learning and memory in mice with a mutation of the candidate dyslexia susceptibility gene Dyx1c1

“…Dyslexia can be deconstructed into underlying core components, known as “intermediate phenotypes”. These include deficits in phonological processing (Kovelman et al, 2012; Melby-Larvag, Lyster & Hulme, 2012; Peyrin et al, 2012), short-term and/or working memory (Beneventi et al, 2010; Gathercole et al, 2006; Menghini et al, 2010), visuospatial attention (Franceschini, 2012; Gabrieli & Norton, 2012), and rapid auditory processing (Cohen-Mimran & Sapir, 2007; Fitch & Szalkowski, 2012; Hamalainen, Salminen & Leppanen, 2013). Other behavioral deficits that have been specifically associated with dyslexia include naming speed, motor functioning and visual processing of motion (Denckla & Rudel, 1976; Liao et al, 2015; Capellini, Coppede & Valle, 2010; Olulade, Napeliello & Eden, 2013).…”