Letter transpositions within morphemes and across morpheme boundaries

Recent evidence has revealed conflicting results regarding the influence of letter transpositions during the recognition of morphologically complex words. While some studies suggest that the disruption of the morpheme boundary through across-boundary transpositions (e.g., darnkess) leads to the absence of masked transposed-letter (TL) priming, other studies have found that TL priming occurs independently of whether or not letters have been transposed across the boundary. We conducted three experiments to test whether the difference between TL- within and TL-across priming is modulated by (a) the transposition of internal versus external letters of the stem (Experiment 1), (b) the overall proportion of affixed trials (Experiment 2), or (c) the relative frequency between prime and target (Experiment 3). The results revealed equal TL-within and TL-across boundary priming across all three experiments, which adds to previous findings suggesting that across-boundary transpositions do not interfere with the recognition of morphologically complex words.     

Magnocellular facilitation of flanked-letter identification disappears with strong flanker interference

Previously, we obtained evidence to suggest that the magnocellular system may reduce interference from flankers during flanked-letter identification. To understand this phenomenon better, we combined the data of our previous experiments, which all used the same flanking letter, and focused on the different target letters that were used. The new analysis showed that after an initial increase, magnocellular facilitation decreased and ultimately disappeared, as the target–flanker combination's level of interference increased. The initial increase was partly while the later decrease was fully replicated in two new experiments that focused on two different target letters while manipulating flanker identity. The outcome of a third new experiment studying the type of interference reduced suggested that although crowding contributed to total interference, it was insensitive to magnocellular mediation. Our results may be understood to reflect the involvement of the magnocellular system in an attentional-selection mechanism that is silenced by surround suppression.     

On the time-course of adjacent and non-adjacent transposed-letter priming

We compared effects of adjacent (e.g. atricle-ARTICLE) and non-adjacent (e.g. actirle-ARTICLE) transposed-letter (TL) primes in an event-related potential (ERP) study using the sandwich priming technique. TL priming was measured relative to the standard double-substitution condition. We found significantly stronger priming effects for adjacent transpositions than non-adjacent transpositions (with two intervening letters) in behavioural responses (lexical decision latencies), and the adjacent priming effects emerged earlier in the ERP signal, at around 200-ms post-target onset. Non-adjacent priming effects emerged about 50 ms later and were short-lived, being significant only in the 250- to 300-ms time-window. Adjacent transpositions on the other hand continued to produce priming in the N400 time-window (300- to 500-ms post-target onset). This qualitatively different pattern of priming effects for adjacent and non-adjacent transpositions is discussed in the light of different accounts of letter transposition effects and the utility of drawing a distinction between positional flexibility and positional noise.     

Letter names and phonological awareness help children to learn letter-sound relations

Two experimental training studies with Portuguese-speaking preschoolers in Brazil were conducted to investigate whether children benefit from letter name knowledge and phonological awareness in learning letter-sound relations. In Experiment 1, two groups of children were compared. The experimental group was taught the names of letters whose sounds occur either at the beginning (e.g., the letter /be/) or in the middle (e.g., the letter /‘eli/) of the letter name. The control group was taught the shapes of the letters but not their names. Then both groups were taught the sounds of the letters. Results showed an advantage for the experimental group, but only for beginning-sound letters. Experiment 2 investigated whether training in phonological awareness could boost the learning of letter sounds, particularly middle-sound letters. In addition to learning the names of beginning- and middle-sound letters, children in the experimental group were taught to categorize words according to rhyme and alliteration, whereas controls were taught to categorize the same words semantically. All children were then taught the sounds of the letters. Results showed that children who were given phonological awareness training found it easier to learn letter sounds than controls. This was true for both types of letters, but especially for middle-sound letters.     

Holographic string encoding

In this article, we apply a special case of holographic representations to letter position coding. We translate different well-known schemes into this format, which uses distributed representations and supports constituent structure. We show that in addition to these brain-like characteristics, performances on a standard benchmark of behavioral effects are improved in the holographic format relative to the standard localist one. This notably occurs because of emerging properties in holographic codes, like transposition and edge effects, for which we give formal demonstrations. Finally, we outline the limits of the approach as well as its possible future extensions.     

Symbol-string sensitivity and children's reading

In this study of primary school children, a novel 'symbol-string' task is used to assess sensitivity to the position of briefly presented non-alphabetic but letter-like symbols. The results demonstrate that sensitivity in the symbol-string task explains a unique proportion of the variability in children's contextual reading accuracy. Moreover, developmental dyslexic readers show reduced sensitivity in this task, compared to chronological age controls. The results suggest that limitations set by visuo-spatial processes and/or attentional iconic memory resources may constrain children's reading accuracy.     

Phonological awareness and the use of phonological similarity in letter-sound learning

The effects of the phonological similarity between a letter sound and the sound in a spoken word, and phonological awareness on letter-sound learning were examined. Two groups of 41 kindergartners were taught four letter sounds. First, both groups had to learn the associations between four symbols and four familiar words. Next, both groups were taught the letter sounds that were paired to these same symbols. Each letter sound corresponded to the first sound of the word that was previously associated with that symbol in the phonological similarity group, whereas such a relation was absent in the other group. In addition, measures of vocabulary, letter knowledge, and phonological awareness were administered. Phonological similarity facilitated letter-sound learning. Individual differences in phonological awareness had a strong effect on letter-sound learning even after current letter knowledge was controlled. Unexpectedly, the effects of phonological awareness and the ability to use phonological similarity on letter-sound learning were found to be independent.     

The role of Hebrew letter names in early literacy: the case of multiphonemic acrophonic names

English-speaking children spell letters correctly more often when the letters' names are heard in the word (e.g., B in beach vs. bone). Hebrew letter names have been claimed to be less useful in this regard. In Study 1, kindergartners were asked to report and spell initial and final letters in Hebrew words that included full (CVC), partial (CV), and phonemic (C) cues derived from these letter names (e.g., kaftor, kartis, kibepsilonl, spelled with /kaf/). Correct and biased responses increased with length of congruent and incongruent cues, respectively. In Study 2, preschoolers and kindergartners were asked to report initial letters with monosyllabic or disyllabic names (e.g., /kaf/ or /samepsilonx/, respectively) that included the cues described above. Correct responses increased with cue length; the effect was stronger with monosyllabic letter names than with disyllabic letter names, probably because the cue covered a larger ratio of the letter name. Phonological awareness was linked to use of letter names.     

Transposed-letter priming effect in Hebrew in the same–different task

We investigated the interaction between morphological structure and transposed-letter priming using the same–different task with Hebrew, a Semitic language in which morphology has been shown to play a key role in visual word recognition. In contrast to the results observed with lexical decision (e.g., Velan & Frost, 2009, 2011), a transposed-letter priming effect was observed irrespective of the morphological structure of the words. We take these results to suggest that morphological decomposition occurs only in the service of lexical access. We discuss further a unique feature of written Arabic, another Semitic language, to explain the apparent conflict between our findings and those reported by Perea, Abu Mallouh, García-Orza, and Carreiras (2010).     

Flank to the left,flank to the right: Testing the modified receptive field hypothesis of letter-specific crowding

The present study tested for effects of number of flankers positioned to the left and to the right of target characters as a function of visual field and stimulus type (letters or shapes). On the basis of the modified receptive field hypothesis (Chanceaux & Grainger, 2012), we predicted that the greatest effects of flanker interference would occur for leftward flankers with letter targets in the left visual field. Target letters and simple shape stimuli were briefly presented and accompanied by either 1, 2, or 3 flankers of the same category either to the left or to the right of the target, and in all conditions with a single flanker on the opposite side. Targets were presented in the left or right visual field at a fixed eccentricity, such that targets and flankers always fell into the same visual field. Results showed greatest interference for leftward flankers associated with letter targets in the left visual field, as predicted by the modified receptive field hypothesis.