No solid empirical evidence for the solid (serial order learning impairment) hypothesis of dyslexia.

Abstract

This article reports on 2 studies that attempted to replicate the findings of a study by Szmalec, Loncke, Page, and Duyck (2011) on Hebb repetition learning in dyslexic individuals, from which these authors concluded that dyslexics suffer from a deficit in long-term learning of serial order information. In 2 experiments, 1 on adolescents (N = 59) and 1 on children (N = 57), no empirical evidence was obtained for impaired Hebb learning in dyslexics, whether the same data-analytical procedure as Szmalec et al. was used or whether some methodological improvements were applied (e.g., using a more sensitive index of Hebb learning, and equating groups on filler performance with state trace analysis). In an additional state trace analysis, aggregating data over participants, it was shown that performance on the repeated Hebb sequences was almost perfectly predictable from performance on the nonrepeated sequences (fillers). The implications of these findings are outlined for the current discussion on the mechanisms for encoding immediate serial recall and long-term sequence learning and for computational models attempting to simulate these mechanisms.

Short‐term Memory in Childhood Dyslexia: Deficient Serial Order in Multiple Modalities

“…Of the few relevant studies in children, the findings support the conclusion that there is a serial order memory deficit (Martinez Perez, Majerus, Mahot, & Poncelet, 2012) and refute the suggestion that there is not (Staels & van den Broeck, 2014, 2015). At the same time, given that the magnitude of the serial order memory deficit was dependent on a number of test factors in our study (especially the modality and the predictability of the list length), it is not terribly surprising that, under some circumstances, the deficit has not been observed.…”

“…Several previous studies have examined nonverbal, as well as verbal, serial order short-term memory mechanisms in adults who had developmental dyslexia using a variety of methods, and have found some deficits in serial order memory (in Dutch, Hachmann et al, 2014; in Finnish, Laasonen et al, 2012; in French, Martinez Perez et al, 2013, 2015; in English, Romani, Tsouknida, & Olson, 2015; Wang, Xuan, & Jarrold, 2016). There are very few relevant studies with children, and they have differed in suggesting that there is a serial order memory deficit (in French: Martinez Perez, Majerus, Mahot, & Poncelet, 2012) or that there is not (with a similar population: Staels & van den Broeck, 2014, 2015). …”

The procedural learning deficit hypothesis of language learning disorders: we see some problems

“…As documented in the introduction, many studies have reported deficits on a range of implicit learning measures in children with language impairment (Hedenius, ; Hsu & Bishop, ; Lum et al., ) or dyslexia (Howard et al., ; Vicari et al., ). However, the findings from previous studies are distinctly mixed, with many null results (Gabriel et al., ; Lum & Bleses, ; Majerus, ; Staels & Van den Broeck, ). Methodologically, most studies in this area share a number of undesirable characteristics: (1) the studies use extreme group designs; (2) sample sizes are small, giving low statistical power; (3) only a single measure, or a limited range of measures of learning and memory are used in any one study; (4) the studies do not report reliability estimates for the measures of learning.…”

“…() also found dyslexic adults to be impaired on a non‐verbal visuo‐spatial Hebb task using sequences of dot locations, suggestive of a domain‐general impairment. However, once again findings are mixed and Staels and Van den Broeck () found no evidence of impaired learning on a verbal Hebb task in adolescents or children with dyslexia and nor did Majerus et al. () in a study of children with SLI.…”

Does learning to read shape verbal working memory?

“…More recently, some researchers have highlighted the contribution to decoding skills of either serial order memory capacity (e.g., Majerus, Poncelet, Greffe, & Van der Linden, 2006;Martinez Perez, Majerus, & Poncelet, 2012a) or the consolidation (or transfer) of serial-order information into a stable LTM trace (Szmalec, Loncke, Page, & Duyck, 2011; but see Staels & Van den Broeck, 2014a). For instance, in a 1-year longitudinal study starting in kindergarten, phonemic awareness (assessed by a phoneme identification task) and serial order STM (measured by a serial order reconstruction task 8 ), but not item STM (measured by monosyllabic nonword repetition under articulatory suppression), predicted independent variance in decoding abilities in first grade, even after controlling for nonverbal reasoning, vocabulary, and initial letter knowledge (Martinez Perez, Majerus, Mahot, & Poncelet, 2012b; see also Nithart et al, 2011).…”