Letter Position Coding Research Articles

Readers encode absolute letter positions

Reading research has long been concerned with the question of whether the reading brain accesses lexical representations via absolute or relative letter position information. In recent years, important results have been obtained with the flanker lexical decision task. Studies have shown faster decisions about target words (e.g., ‘rock’) when flanked by related letters (‘ro rock ck’) than unrelated letters (‘st rock ep')—and crucially, equal facilitation upon switching flanker positions (‘ck rock ro'), pointing to relative rather than absolute letter position coding. Yet, a later study employing longer targets and flankers yielded detrimental effects of switching flanker positions. In order to get a better grasp on the equivocal evidence thus far, here we carried out an extensive test of flanker relatedness and position effects, using various target and flanker lengths, all within a single experiment. We observed a clear reduction of flanker relatedness effects upon switching flanker positions, and this held true across target and flanker lengths. The present results unambiguously suggest that lexical access is driven by absolute letter position information, and furthermore, are accurately predicted by the recent PONG model (Snell, 2024b).

Flexible letter-position coding in Chinese-English L2 bilinguals: Evidence from eye movements.

Theories suggest that efficient recognition of English words depends on flexible letter-position coding, demonstrated by the fact that transposed-letter primes (e.g., JUGDE-judge) facilitate written word recognition more than substituted-letter primes (e.g., JUFBE-judge). The multiple route model predicts that reading experience should drive more flexible letter-position coding as readers transition from decoding words letter-by-letter to recognising words as wholes. This study therefore examined whether letter-position is coded flexibly in second-language English sentence reading for native Chinese speakers, and if this is influenced by English proficiency. Eye movements were measured while 54 adult native Chinese speakers read English sentences including either a real word (e.g., cheaply), a transposed-letter nonword (e.g., "chepaly"), or a substituted-letter nonword (e.g., "chegely"). Flexible letter-position coding was observed in initial and later processing stages-reading times were longer for substituted-letter than transposed-letter nonwords. In addition, reading times were longer in both initial and later processing stages for transposed-letter nonwords than real words, indicating that, despite encoding letter-position flexibly, readers processed letter-position. Although pre-registered frequentist analyses suggested that English proficiency did not predict overall reading times, Bayes Factors indicated that there was evidence for such a relationship. It is therefore likely that this proficiency analysis suffered from low power. Finally, neither frequentist nor Bayes Factor analyses suggested that English proficiency influenced the difference in reading times between different target word types, i.e., the nature of letter-position coding. Overall, these results suggest that highly proficient L2 learners code letter-position flexibly.

Raeding with the fingres: Towards a universal model of letter position coding

Letter position coding in word recognition has been widely investigated in the visual modality (e.g., labotarory is confusable with laboratory), but not as much in the tactile modality using braille, leading to an incomplete understanding of whether this process is modality-dependent. Unlike sighted readers, braille readers do not show a transposed-letter similarity effect with nonadjacent transpositions (e.g., labotarory = labodanory; Perea et al., 2012). While this latter finding was taken to suggest that the flexibility in letter position coding was due to visual factors (e.g., perceptual uncertainty in the location of visual objects (letters)), it is necessary to test whether transposed-letter effects occur with adjacent letters to reach firm conclusions. Indeed, in the auditory modality (i.e., another serial modality), a transposed-phoneme effect occurs for adjacent but not for nonadjacent transpositions. In a lexical decision task, we examined whether pseudowords created by transposing two adjacent letters of a word (e.g., laboartory) are more confusable with their base word (laboratory) than pseudowords created by replacing those letters (laboestory) in braille. Results showed that transposed-letter pseudowords produced more errors and slower responses than the orthographic controls. Thus, these findings suggest that the mechanism of serial order, while universal, can be shaped by the sensory modality at play.

Which Factors Modulate Letter Position Coding in Pre-literate Children?

One of the central landmarks of learning to read is the emergence of orthographic processing (i.e., the encoding of letter identity and letter order): it constitutes the necessary link between the low-level stages of visual processing and the higher-level processing of words. Regarding the processing of letter position, many experiments have shown worse performance in various tasks for the transposed-letter pair judge-JUDGE than for the orthographic control jupte-JUDGE. Importantly, 4-y.o. pre-literate children also show letter transposition effects in a same-different task: TZ-ZT is more error-prone than TZ-PH. Here, we examined whether this effect with pre-literate children is related to the cognitive and linguistic skills required to learn to read. Specifically, we examined the relation of the transposed-letter in a same-different task with the scores of these children in phonological, alphabetic and metalinguistic awareness, linguistic skills, and basic cognitive processes. To that end, we used a standardized battery to assess the abilities related with early reading acquisition. Results showed that the size of the transposed-letter effect in pre-literate children was strongly associated with the sub-test on basic cognitive processes (i.e., memory and perception) but not with the other sub-tests. Importantly, identifying children who may need a pre-literacy intervention is crucial to minimize eventual reading difficulties. We discuss how this marker can be used as a tool to anticipate reading difficulties in beginning readers.

Do Grading Gray Stimuli Help to Encode Letter Position?

Numerous experiments in the past decades recurrently showed that a transposed-letter pseudoword (e.g., JUGDE) is much more wordlike than a replacement-letter control (e.g., JUPTE). Critically, there is an ongoing debate as to whether this effect arises at a perceptual level (e.g., perceptual uncertainty at assigning letter position of an array of visual objects) or at an abstract language-specific level (e.g., via a level of “open bigrams” between the letter and word levels). Here, we designed an experiment to test the limits of perceptual accounts of letter position coding. The stimuli in a lexical decision task were presented either with a homogeneous letter intensity or with a graded gray intensity, which indicated an unambiguous letter order. The pseudowords were either transposed-letter pseudowords or replaced-letter pseudowords (e.g., jugde vs. jupte). The results showed much longer response times and substantially more errors in the transposed-letter pseudowords than in the replacement-letter pseudowords, regardless of visual format. These findings favor the idea that language-specific orthographic element factors play an essential role when encoding letter position during word recognition.

What, Where, When and How of Visual Word Recognition: A Bibliometrics Review.

The neural/mental operations involved in the process of visual word recognition (VWR) are fundamental for the efficient comprehension of written/printed words during reading. The present study used CiteSpace, a visual analysis software, to identify the intellectual landscape where VWR has been reviewed in the past decade. Thus, synthesized co-citation networks were analyzed to explore and discuss the main questions raised in the VWR literature: the research fronts and the emerging trends of research on this topic. Our results showed that the main questions addressed in VWR studies during the last decade have been focused on four main aspects related to "what," "where," "when," and "how" of VWR; to be specific, the different types of representations assessed during VWR ("what"), the locations and the timing of the brain activity involved in VWR ("where" and "when"), and the interactivity among different representations during processing ("how"). Among the revised studies, letter position coding was found to be the main topic of interest, possibly reflecting the critical role of this process. Furthermore, the evidence found in these studies consistently supported that VWR implies access to phonological, semantic, and morphological representations, which interact and modulate the processing of written words, particularly during early stages. Altogether, our findings showed the evolution in VWR literature regarding the different cognitive and neural operations involved in this process, highlighting the growing interest over the last decade toward the top-down way that mental representations interact.

Effects of adult aging on letter position coding in reading: Evidence from eye movements.

It is well-established that young adults encode letter position flexibly during natural reading. However, given the visual changes that occur with normal aging, it is important to establish whether letter position coding is equivalent across adulthood. In 2 experiments, young (18–25 years) and older (65+ years) adults’ were recorded while reading sentences with words containing transposed adjacent letters. Transpositions occurred at beginning (rpoblem), internal (porblem), or end (problme) locations in words. In Experiment 1, these transpositions were present throughout reading. By comparison, Experiment 2 used a gaze-contingent paradigm such that once the reader’s gaze moved past a word containing a transposition, this word was shown correctly and did not subsequently change. Both age groups showed normal levels of comprehension for text including words with transposed letters. The pattern of letter transposition effects on eye movements was similar for the young and older adults, with greater increases in reading times when external relative to internal letters were transposed. In Experiment 1, however, effects of word beginning transpositions during rereading were larger for the older adults. In Experiment 2 there were no interactions, confirming that letter position coding is similar for both age groups at least during first-pass processing of words. These findings show that flexibility in letter position encoding during the initial processing of words is preserved across adulthood, although the interaction effect in rereading in Experiment 1 also suggests that older readers may use more stringent postlexical verification processes, for which the accuracy of word beginning letters is especially important.

An electrophysiological investigation of orthographic spatial integration in reading

During reading, word recognition speed is influenced by the amount of orthographic overlap with surrounding words. The nature of this phenomenon is not understood: some theories attribute it to low-level visual operations (i.e., parafoveal feature detectors influencing foveal letter detectors), whereas other theories assume that orthographic processing (i.e., letter position coding and word activation) occurs across multiple words in parallel. To arbitrate between these theories, we used electroencephalography to reveal the time course of orthographic spatial integration in a lexical decision task. Foveal target words were flanked on each side by parafoveal words, manipulated across three conditions: repetition flankers (e.g. rock rock rock), unrelated flankers (step rock step) and a no-flanker condition. Linear mixed-effect models were constructed to analyze EEG data on a trial-by-trial basis. Word recognition was worse in the unrelated flanker condition than in the repetition and no-flanker conditions. This behavioral pattern was accompanied by increased negativity in the N250 and N400 windows, associated with the activation of sub-lexical and lexico-semantic representations, respectively. Crucially, the absence of effects prior to 200 ms post-stimulus onset provides evidence against the involvement of low-level visual processes. We conclude that orthographic spatial integration is driven by parallel processing of multiple words, which leads to the activation of a larger set of sub-lexical nodes and more difficult processing at the lexical level when those words are orthographically unrelated.

No flexibility in letter position coding in Korean.

Substantial research across Indo-European languages suggests that readers display a degree of uncertainty in letter position coding. For example, readers perceive transposed-letter stimuli, such as jugde, as similar to their base words (e.g., judge). However, tolerance to disruptions of letter order is not apparent in all languages, suggesting that critical aspects of the writing system may shape the nature of position coding. We investigated readers' tolerance to these disruptions in Korean, a writing system characterized by a high degree of orthographic confusability. Results of three Korean masked priming experiments revealed robust identity priming effects, but no indication of priming due to shared letters or syllables in different positions. Two further masked priming experiments revealed where the Korean findings deviate from English. These results support the claim that the nature of the writing system influences the precision of orthographic representations used in reading. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Orthographic and phonological priming effects in the same-different task.

Masked priming tasks have been used widely to study early orthographic processes—the coding of letter position and letter identity. Recently, using masked priming in the same–different task Lupker, Nakayama, and Perea (2015a) reported finding a phonological priming effect with primes presented in Japanese Katakana, and English target words presented in the Roman alphabet, and based on this finding, suggested that previously reported effects in the same–different task in the literature could be based on phonology rather than orthography. In this article, the authors explain why the design of Lupker et al.’s experiment does not address this question; they then report 2 new experiments that do. The results indicate that the priming produced by orthographically similar primes in the same–different task for letter strings presented in the Roman alphabet is almost exclusively orthographic in origin, and phonology makes little contribution. The authors offer an explanation for why phonological priming was observed when the prime and target are presented in different scripts but not when they are presented in the same script.

Who are the noisiest neighbors in the hood? Using error analyses to study the acquisition of letter-position processing.

This research examines the acquisition of letter-position processing. Study 1 investigated letter-position processing in Grades 1-6 and adult readers, using the occurrence of specific error types as the outcome measure. Between Grades 1 and 2, there was a shift from making more other-word to making more letter-position errors. This shift was a function of reading proficiency, not of years of reading instruction. Based on the multiple-route model of reading development (Grainger, Lété, Bertand, Dufau, & Ziegler, 2012), we argue that the fact that children make fewer other-word errors (i.e., mostly letter-identity errors) opens up the opportunity for them to make "the more advanced" letter-position errors. Finally, skilled adult readers still made fewer letter-position errors than typical readers in Grade 6, suggesting that the acquisition process is not finalized by the end of primary school. In Study 2, we directly compared letter-position processing with letter-identity processing. Thirty children in Grade 3 and 30 children in Grade 4 read aloud words with and without higher-frequency distractors. Children more often misread a word with a higher-frequency distractor than without such a distractor and this effect was stronger for below-average than for above-average readers. Converging with the results of Study 1, we found that a letter-position distractor is more disruptive than a letter-identity distractor. These results confirm that the acquisition of letter-position processing lags behind of that of letter-identity processing. The results are discussed within the framework of the Lexical Tuning Hypothesis (Castles, Davis, Cavalot, & Forster, 2007), which stresses the importance of feedback between letter (identity and position) coding and (developing) orthographic representations. (PsycINFO Database Record

Can letter position encoding be modified by visual perceptual elements?

A plethora of studies has revealed that letter position coding is relatively flexible during word recognition (e.g., the transposed-letter [TL] pseudoword CHOLOCATE is frequently misread as CHOCOLATE). A plausible explanation of this phenomenon is that letter identity and location are not perfectly bound as a consequence of the limitations of the visual system. Thus, a complete characterization of letter position coding requires an examination of how letter position coding can be modulated by visual perceptual elements. Here we conducted three lexical decision experiments with TL and replacement-letter pseudowords that manipulated the visual characteristics of the stimuli. In Experiment 1, each syllable was presented either in a different colour or monochromatically (e.g., vs. ) with the transposition occurring across syllables. In Experiment 2, the critical letters had a consistent contrast or not (e.g., vs. ). In Experiment 3, the stimuli were presented either simultaneously or serially, letter by letter (i.e., as occurs in braille reading). Results showed that whereas colouring differently each syllable only produced a small nonsignificant reduction of the TL effect, the other two manipulations-presenting the two critical letters with an altered contrast and presenting the letters one at a time-reduced, but did not eliminate, the magnitude of the TL effect relative to the regular format. Although these findings are consistent with models that postulate an early perceptual locus of the TL effect, the robustness of the TL effect suggests that letter position coding also has an orthographic abstract component.

Parafoveal letter-position coding in reading.

The masked-priming lexical decision task has been the paradigm of choice for investigating how readers code for letter identity and position. Insight into the temporal integration of information between prime and target words has pointed out, among other things, that readers do not code for the absolute position of letters. This conception has spurred various accounts of the word recognition process, but the results at present do not favor one account in particular. Thus, employing a new strategy, the present study moves out of the arena of temporal- and into the arena of spatial information integration. We present two lexical decision experiments that tested how the processing of six-letter target words is influenced by simultaneously presented flanking stimuli (each stimulus was presented for 150 ms). We manipulated the orthographic relatedness between the targets and flankers, in terms of both letter identity (same/different letters based on the target's outer/inner letters) and letter position (intact/reversed order of letters and of flankers, contiguous/noncontiguous flankers). Target processing was strongly facilitated by same-letter flankers, and this facilitatory effect was modulated by both letter/flanker order and contiguity. However, when the flankers consisted of the target's inner-positioned letters alone, letter order no longer mattered. These findings suggest that readers may code for the relative position of letters using words' edges as spatial points of reference. We conclude that the flanker paradigm provides a fruitful means to investigate letter-position coding in the fovea and parafovea.

Word and pseudoword superiority effects: Evidence from a shallow orthography language.

The word superiority effect (WSE) denotes better recognition of a letter embedded in a word rather than in a pseudoword. Along with WSE, also a pseudoword superiority effect (PSE) has been described: It is easier to recognise a letter in a legal pseudoword than in an unpronounceable nonword. At the current state of the art, both WSE and PSE have been mainly tested with English speakers. This study uses the Reicher-Wheeler paradigm with native speakers of Italian (a shallow orthography language). Different from English and French, we found WSE for reaction times (RTs) only, whereas PSE was significant for both accuracy and RTs. This finding indicates that in the Reicher-Wheeler task, readers of a shallow orthography language can effectively rely on both the lexical and the sublexical routes. As to the effect of letter position, a clear advantage for the first-letter position emerged, a finding suggesting a fine-grained processing of the letter strings with coding of letter position and indicating the role of visual acuity and crowding factors.

How orthographic-specific characteristics shape letter position coding: The case of Thai script

A central question for any model of visual word identification is the representation of the position at which letters are encoded (e.g., calm vs. clam). In this article, we examine whether the orthographic-specific characteristics of a writing system-namely, Thai-shape the process of letter position coding. Thai is an alphabetic script that lacks interword spaces and has an orthographic order that does not necessarily correspond to the phonological order for initial vowels. This implies that the initial letter position coding in Thai needs to be flexible enough that readers can successfully encode the letter positions of words. To compare letter position coding in Thai to that in English, we conducted an experiment that paralleled Experiment 3 in Gomez, Ratcliff, and Perea (Psychological Review, 115, 577-600, 2008), including 23 conditions (single-letter replacements, letter transpositions, letter migrations, and a corresponding control). We obtained fits from Gomez etal.'s overlap model, which is a model that has been shown to account for letter position coding in the Roman alphabet across this variety of letter manipulations. The overlap model was found to successfully fit the Thai data. Our results revealed that the position encoding was better for the first letter than for the rest of the positions in both languages; however, in English the position uncertainty grows as a function of letter order quite abruptly, whereas in Thai it grows gradually. Thus, the orthographic-specific characteristics of the Thai writing system do play a role in shaping the process of letter position coding.

What causes the greater perceived similarity of consonant-transposed nonwords?

Nonwords created by transposing two non-adjacent orthographic consonants (CONDISER) have been reported to produce more priming for their baseword (CONSIDER), and to be classified as a nonword less readily than nonwords created by transposing two orthographic vowels (CINSODER). We investigate the origin of this difference and its relevance for theories of letter position coding. In the unprimed versions of the lexical decision and same–different tasks, a consonant–vowel difference was found in the transposition condition, not when those letters are substituted (Experiment 1). We found that when transpositions involved the disruption of a consonant cluster (OPMITAL), reaction times were slowed compared to when transpositions involved only letters that are separated (CHOLOCATE; Experiment 2). As transpositions more frequently disrupt in consonant clusters than vowel clusters, this introduces a confound in studies investigating consonant and vowel transposition effects. Consistent with the idea that letter order is harder to resolve in clusters, the difference between consonants and vowels was eliminated when transpositions involve singleton consonants or vowels rather than those in clusters (Experiment 3). These results suggest that the precision of position coding does not differ between consonants and vowels, but that consonant–vowel status plays a role in structuring orthographic representations.

On the nature of consonant/vowel differences in letter position coding: Evidence from developing and adult readers.

In skilled adult readers, transposed-letter effects (jugde-JUDGE) are greater for consonant than for vowel transpositions. These differences are often attributed to phonological rather than orthographic processing. To examine this issue, we employed a scenario in which phonological involvement varies as a function of reading experience: A masked priming lexical decision task with 50-ms primes in adult and developing readers. Indeed, masked phonological priming at this prime duration has been consistently reported in adults, but not in developing readers (Davis, Castles, & Iakovidis, 1998). Thus, if consonant/vowel asymmetries in letter position coding with adults are due to phonological influences, transposed-letter priming should occur for both consonant and vowel transpositions in developing readers. Results with adults (Experiment 1) replicated the usual consonant/vowel asymmetry in transposed-letter priming. In contrast, no signs of an asymmetry were found with developing readers (Experiments 2-3). However, Experiments 1-3 did not directly test the existence of phonological involvement. To study this question, Experiment 4 manipulated the phonological prime-target relationship in developing readers. As expected, we found no signs of masked phonological priming. Thus, the present data favour an interpretation of the consonant/vowel dissociation in letter position coding as due to phonological rather than orthographic processing.

Does location uncertainty in letter position coding emerge because of literacy training?

In the quest to unveil the nature of the orthographic code, a useful strategy is to examine the transposed-letter effect (e.g., JUGDE is more confusable with its base word, JUDGE, than the replacement-letter nonword JUPTE). A leading explanation of this phenomenon, which is line with models of visual attention, is that there is perceptual uncertainty at assigning letters ("objects") to positions. This mechanism would be at work not only with skilled readers but also with preliterate children. An alternative explanation is that the transposed-letter effect emerges at an orthographic level of processing as a direct consequence of literacy training. To test these accounts, we conducted a same-different matching experiment with preliterate 4-year-old children using same versus different trials (created by letter transposition or replacement). Results showed a significantly larger number of false positives (i.e., "same" responses) to transposed-letter strings than to 1/2 replacement-letter strings. Therefore, the present data favor the view that the visual processing of location information is inherently noisy and rule out an interpretation of confusability in letter position coding as emerging from literacy training. (PsycINFO Database Record

How do Scrabble players encode letter position during reading?

A number of experiments with skilled adult readers have shown that a transposed-letter pseudoword (e.g., CHOLOCATE) is considerably more word-like than a control replacement-letter pseudoword (e.g., CHOTONATE). For instance, in lexical decision, response times are longer and less accurate for CHOLOCATE than for CHOTONATE (i.e., a transposed-letter effect). Here, we examined how letter position coding is attained in individuals who excel in orthographic-lexical processing: competitive Scrabble players. To this end, we conducted a lexical decision experiment with two types of pseudowords (transposed-letter vs. replacement-letter pseudowords). Data showed that while the transposed-letter effect does occur in expert Scrabble players, the magnitude of the effect is dramatically smaller than in a control group of university students—in particular, for the accuracy data. The parameters responsible for the flexibility of letter position coding in models of visual word recognition must be modulated by the degree of expertise in orthographic-lexical processing.

The devil is in the details of hand movement

Research with native-speaking monolinguals demonstrates that orthographic coding during lexical access is flexible in terms of letter positioning. Evidence for this comes in part from the observation of priming from transposed-letter (TL) non-words (jugde/judge), which is assumed to arise from spread of activation throughout an orthographically-defined neighborhood. The present study tested the hypothesis that, for bilinguals, orthographic coding of letter position is influenced by cross-language lexical activation. TL non-words were created from English-Spanish cognates that differed in their degree of orthographic overlap as well as from non-cognates. In Experiment 1, these served as primes in a masked lexical decision task. In Experiment 2, they were presented as targets in a mouse-tracking lexical decision task. In both experiments Spanish-­English bilinguals’ lexical decision performance reflected greater TL priming for cognates relative to non-cognates and for cognates with more orthographic overlap relative to cognates with less orthographic overlap.