Phonological Preparation in Korean: Phoneme, or Syllable or Another Unit?

With three experiments, the present study investigated the primary phonological preparation (PP) unit in spoken word production in Korean. Adopting the form preparation paradigm, 23 native Korean speakers named pictures in homogenous or heterogenous lists. In homogenous lists, the names of the pictures shared the same initial phoneme (Experiment 1), initial consonant + vowel (i.e., CV) body (Experiment 2), or initial consonant + vowel + consonant (CVC) syllable (Experiment 3); and in heterogenous lists, the names did not share any phonological components systematically. Compared to naming pictures in heterogenous lists, participants’ naming speed was significantly faster when the initial body or the initial syllable of target names was shared. However, this form preparation effect was not shown in Experiment 1, when only the initial phoneme was shared. These results suggested that the body serves as the primary PP unit in Korean, that is, native Korean speakers tend to plan spoken words in a body–coda fashion, probably due to a joint contribution from the strong prevalence of the CV structure and early literacy instructional approach.

Reading comprehension on word- and sentence-level can be predicted by orthographic knowledge for German children with poor reading proficiency

Previous studies mostly examined the role of orthographic knowledge in basic reading processing (i.e., word-reading), however, regarding higher reading processing (i.e., sentence- and text-comprehension), mixed results were reported. In addition, previous research in transparent languages, such as German, focused mostly on typically skilled readers. The aim of this study was to examine the role of orthographic knowledge in basic reading processing (word-reading) as well as in higher reading processing (sentence- and text-comprehension), in addition to phonological awareness and naming speed in a sample of German elementary school poor readers. For this purpose, data from 103 German third-graders with poor reading proficiency were analyzed via multiple linear regression analysis. Analyses revealed that orthographic knowledge contributes to reading at word- and sentence-level, but not at text-level in German third-graders with poor reading proficiency, over and above phonological awareness and naming speed. These findings support that orthographic knowledge should be considered as a relevant reading related predictor. Therefore, it would be reasonable to include the assessment of orthographic knowledge skills in diagnostic procedures to identify children at risk to develop reading difficulties, besides phonological awareness and naming speed.

The role of orthographic knowledge for reading performance in German elementary school children

Reading is crucial for successful participation in the modern world. However, 3-8% (e.g., Moll et al., 2014) of children in elementary school age show reading difficulties, which can lead to limited education and enhance risks of social and financial disadvantages (Valtin, 2017). Therefore, it is important to identify reading relevant components (Tippelt & Schmidt-Hertha, 2018). In this context, especially phonological awareness (i.e., awareness of the sound structure of the language) and naming speed (i.e., fast and automatized retrieval of information) were identified as significant components for reading skills (e.g., Georgiou et al., 2012; Landerl & Thaler, 2006; Vellutino, Fletcher, Snowling, & Scanlon, 2004). One further component, which is of growing interest to the recent research, is orthographic knowledge. It comprises the knowledge about the spelling of specific words (word-specific orthographic knowledge) and about legal letter patterns (general orthographic knowledge; Apel, 2011). Previous research focused predominantly on examining the role of orthographic knowledge on basic reading level, including word identification and word meaning (Conrad et al., 2013; Rothe et al., 2015). The relationship between orthographic knowledge and reading comprehension as the core objective of reading, including understanding of the relationship between words within a sentence as well as building a coherence between sentences (Perfetti et al., 2005), was on the contrary scarcely the object of research. The first goal of this dissertation is, therefore, to provide a remedy by investigating the role of orthographic knowledge on higher reading processes (sentence- and text-level). The scarce body of research investigating children with reading difficulties provide a mixed result pattern (e.g., Ise et al., 2014). Therefore, this dissertation aims at clarifying the influence of orthographic knowledge on word-, sentence-, and text-level in children without and with reading difficulties. A thorough understanding of reading relevant components is also important for conception of interventions aiming at individual reading performance improvements in order to prevent school failure. One promising approach to help children to overcome their reading difficulties is a text-fading based reading training. During this procedure, reading material is faded out letter by letter in reading direction (i.e., in German from left to right; Breznitz & Nevat, 2006). The aim of this manipulation is to prompt the individual to read faster than usual, resulting in reading rate and comprehension improvements (e.g., Nagler et al., 2015). However, the underlying mechanisms leading to improvements of reading performance are still unclear. Considering previous findings showing orthographic skills to influence training outcomes (Berninger et al., 1999), and also word reading performance after a reading intervention (Stage et al., 2003), it seems plausible to include orthographic knowledge when investigating potential training effects. Therefore, this dissertation aims at investigating the predictive value of orthographic knowledge for comprehension performance during the text-fading based reading training. In order to answer the first research question, two empirical papers are implemented (see Appendix A: Zarić et al., 2020 and Appendix B: Zarić & Nagler, 2021), which investigate the role of orthographic knowledge for reading at word-, sentence-, and text-level in German school children without and with reading difficulties. The study by Zarić et al. (2020) examines the incremental predictive value for explained reading variance of both word-specific and general orthographic knowledge in relation to variance amount explained by general intelligence and phonological awareness. For this purpose, data from 66 German third-graders without reading difficulties were analyzed. Correlation and multiple regression analyses have shown that word-specific and general orthographic knowledge contribute a unique significant amount to the variance of reading comprehension on word-, sentence-, and text-level, over and above the explained variance by general intelligence and phonological awareness. In order to answer the question whether word-specific and general orthographic knowledge also explain variance in children with poor reading proficiency, in addition to established predictors phonological awareness and naming speed, the data from 103 German third-graders with reading difficulties were analyzed in a second study (Zarić & Nagler, 2021). The analyses revealed that word-specific and general orthographic knowledge explain a unique significant amount of the variance of reading on word- and sentence-level. On text-level, these two components did not explain a significant amount of unique variance. Here, only phonological awareness was shown to be a significant predictor. The results indicate that the knowledge about the spelling of specific words (word-specific orthographic knowledge) and the knowledge about legal letter patterns (general orthographic knowledge) contribute to reading comprehension on word-level. Following the assumptions, for instance, of the Lexical Quality Hypothesis (Perfetti & Hart, 2002) high-quality orthographic representations are considered to be important for higher reading processes, such as comprehension. ...

Semantic interference through multiple distractors in picture naming in people with aphasia

When we refer to an object or concept by its name, activation of semantic and categorical information is necessary to retrieve the correct lexical representation. While in neurotypical participants it is well established that semantic context can interfere with or facilitate lexical retrieval, these effects are much less studied in people with lesions to the language network and impairment at different steps of lexical- semantic processing.Here we applied a novel picture naming paradigm, where multiple categorically related and unrelated words were presented as distractors before a to-be-named target picture. Using eye tracking we investigated preferential fixation on the cohort members vs non-members. Thereby we could test whether explicit acknowledgement of the category is mandatory to induce semantic interference. We found that in contrast to neurotypical participants (van Scherpenberg, Abdel Rahman, & Obrig, 2020), participants suffering from mild to moderate aphasia did not explicitly acknowledge the categorical relationship, but still showed a large interference effect of ~35 ms. On the contrary, preferential fixation on the categorically related cohort words correlated with higher non-verbal semantic abilities and integrity of the anterior temporal lobe (ATL). This highlights the role of supramodal semantics – putatively housed in the ATL – for explicit semantic processing while semantic interference may be largely independent thereof. Our study adds further evidence to the observation that despite the implicit, automatic nature of semantic processing, it can influence naming speed and accuracy. This may be of particular importance to understand and intervene with linguistic deficits in people with aphasia.

Developmental Trends of Visual Processing of Letters and Objects Using Naming Speed Tasks

Studying the typical development of reading is key to understanding the precise deficits that underlie reading disabilities. An important correlate of efficient reading is the speed of naming arrays of simple stimuli such as letters and pictures. In this cross-sectional study, we examined developmental changes in visual processing that occurs during letter and object naming from childhood to early adulthood in terms of behavioral task efficiency, associated articulation and eye movement parameters, and the coordination between them, as measured by eye-voice span in both the spatial and temporal domains. We used naming speed (NS) tasks, in which participants were required to name sets of letters or simple objects as quickly and as accurately as possible. Single stimulus manipulations were made to these tasks to make the stimuli either more visually and/or phonologically similar to one another in order to examine how these manipulations affected task performance and the coordination between speech and eye movements. Across development there was an increased efficiency in speech and eye movement performance and their coordination in both the spatial and temporal domains. Furthermore, manipulations to the phonological and visual similarity of specific letter and object stimuli revealed that orthographic processing played a greater role than phonological processing in performance, with the contribution of phonological processing diminishing across development. This comprehensive typical developmental trajectory provides a benchmark for clinical populations to elucidate the nature of the cognitive dysfunction underlying reading difficulties.

Flicker fusion thresholds as a clinical identifier of a magnocellular-deficit dyslexic subgroup

The magnocellular-dorsal system is well isolated by high temporal frequency. However, temporal processing thresholds have seldom been explored in developmental dyslexia nor its subtypes. Hence, performances on two, four-alternative forced-choice achromatic flicker fusion threshold tasks modulated at low (5%) and high (75%) temporal contrast were compared in dyslexic and neurotypical children individually matched for age and intelligence (8–12 years, n = 54 per group). As expected, the higher modulation resulted in higher flicker fusion thresholds in both groups. Compared to neurotypicals, the dyslexic group displayed significantly lower ability to detect flicker at high temporal frequencies, both at low and high temporal contrast. Yet, discriminant analysis did not adequately distinguish the dyslexics from neurotypicals, on the basis of flicker thresholds alone. Rather, two distinct dyslexic subgroups were identified by cluster analysis – one characterised by significantly lower temporal frequency thresholds than neurotypicals (referred to as ‘Magnocellular-Deficit’ dyslexics; 53.7%), while the other group (‘Magnocellular-Typical’ dyslexics; 46.3%) had comparable thresholds to neurotypicals. The two dyslexic subgroups were not differentially associated with phonological or naming speed subtypes and showed comparable mean reading rate impairments. However, correlations between low modulation flicker fusion threshold and reading rate for the two subgroups were significantly different (p = .0009). Flicker fusion threshold performances also showed strong classification accuracy (79.3%) in dissociating the Magnocellular-Deficit dyslexics and neurotypicals. We propose that temporal visual processing impairments characterize a previously unidentified subgroup of dyslexia and suggest that measurement of flicker fusion thresholds could be used clinically to assist early diagnosis and appropriate treatment recommendations for dyslexia.

Understanding the biological basis of dyslexia at a neural systems level

We examined the naming speed performance of 18 typically achieving and 16 dyslexic adults while simultaneously recording eye movements, articulations and fMRI data. Naming speed tasks, which require participants to name a list of letters or objects, have been proposed as a proxy for reading and are thought to recruit similar reading networks in the left hemisphere of the brain as more complex reading tasks. We employed letter and object naming speed tasks, with task manipulations to make the stimuli more or less phonologically and/or visually similar. Compared to typically achieving readers, readers with dyslexia had a poorer behavioural naming speed task performance, longer fixation durations, more regressions and increased activation in areas of the reading network in the left-hemisphere. Whereas increased network activation was positively associated with performance in dyslexics, it was negatively related to performance in typically achieving readers. Readers with dyslexia had greater bilateral activation and recruited additional regions involved with memory, namely the amygdala and hippocampus; in contrast, the typically achieving readers additionally activated the dorsolateral prefrontal cortex. Areas within the reading network were differentially activated by stimulus manipulations to the naming speed tasks. There was less efficient naming speed behavioural performance, longer fixation durations, more regressions and increased neural activity when letter stimuli were both phonologically and visually similar. Discussion focuses on the differences in activation within the reading network, how they are related to behavioural task differences, and how progress in furthering the understanding of the relationship between behavioural performance and brain activity can change the overall trajectories of children with reading difficulties by contributing to both early identification and remediation processes.