Do Diacritical Marks Play a Role at the Early Stages of Word Recognition in Arabic?

Effects of word predictability on eye movements during Arabic reading

Contextual predictability influences both the probability and duration of eye fixations on words when reading Latinate alphabetic scripts like English and German. However, it is unknown whether word predictability influences eye movements in reading similarly for Semitic languages like Arabic, which are alphabetic languages with very different visual and linguistic characteristics. Such knowledge is nevertheless important for establishing the generality of mechanisms of eye-movement control across different alphabetic writing systems. Accordingly, we investigated word predictability effects in Arabic in two eye-movement experiments. Both produced shorter fixation times for words with high compared to low predictability, consistent with previous findings. Predictability did not influence skipping probabilities for (four- to eight-letter) words of varying length and morphological complexity (Experiment 1). However, it did for short (three- to four-letter) words with simpler structures (Experiment 2). We suggest that word-skipping is reduced, and affected less by contextual predictability, in Arabic compared to Latinate alphabetic reading, because of specific orthographic and morphological characteristics of the Arabic script.

The role of orthographic cues to stress in Italian visual word recognition

In this study, stress diacritics were used to investigate the processing of stress information in lexical decision. We ran two experiments in Italian, a language in which stress position is not predictable by rule and only final stress-that is, the less common pattern-is orthographically marked with a diacritic. In Experiment 1, a lexical decision task, two factors were manipulated: the stress pattern of words-antepenultimate (nondominant) and penultimate (dominant)-and the presence/absence of the diacritics, signalling the stress position. Participants were faster to categorise stimuli as words when they bear dominant than nondominant stress. However, the advantage disappeared when the diacritic was used. In Experiment 2, a same-different verification task was used in which participants had to decide if a referent word and a target were same (carota-CAROTA, /ka'rɔta/; tavolo-TAVOLO, /'tavolo/) or different. We compared two conditions requiring a "different" response, in which referent and target with dominant and nondominant stress were congruent (caròta-CAROTA; tàvolo-TAVOLO) or incongruent (càrota-CAROTA; tavòlo-TAVOLO) with the word's stress. For words with dominant stress, "different" responses were faster in the incongruent condition than the congruent condition. This congruency effect was not observed for words with nondominant stress pattern. Overall, the data suggest that stress information is based on lexical phonology, and the stress dominance effect has a lexical base in word recognition.

Letter identity and visual similarity in the processing of diacritic letters

Are letters with a diacritic (e.g., â) recognized as a variant of the base letter (e.g., a), or as a separate letter identity? Two recent masked priming studies, one in French and one in Spanish, investigated this question, concluding that this depends on the language-specific linguistic function served by the diacritic. Experiment 1 tested this linguistic function hypothesis using Japanese kana, in which diacritics signal consonant voicing, and like French and unlike Spanish, provide lexical contrast. Contrary to the hypothesis, Japanese kana yielded the pattern of diacritic priming like Spanish. Specifically, for a target kana with a diacritic (e.g., ガ, /ga/), the kana prime without the diacritic (e.g., カ, /ka/) facilitated recognition almost as much as the identity prime (e.g., ガ-ガ = カ-ガ), whereas for a target kana without a diacritic, the kana prime with the diacritic produced less facilitation than the identity prime (e.g., カ-カ < ガ-カ). We suggest that the pattern of diacritic priming has little to do with linguistic function, and instead it stems from a general property of visual object recognition. Experiment 2 tested this hypothesis using visually similar letters of the Latin alphabet that differ in the presence/absence of a visual feature (e.g., O and Q). The same asymmetry in priming was observed. These findings are consistent with the noisy channel model of letter/word recognition (Norris & Kinoshita, Psychological Review, 119, 517-545, 2012a).

Does a mark make a difference? Visual similarity effects with accented vowels

Visual similarity effects are pervasive in masked priming (e.g., T4BLE→TABLE; obiect→OBJECT; docurnent→DOCUMENT) and can be easily explained in terms of uncertainty regarding letter identity. However, recent research failed to show visual similarity effects for primes containing accented vowels (e.g., féliz-FELIZ behaves as fáliz-FELIZ [happy in Spanish]). This null effect has been taken to suggest that accented and non-accented vowels (e.g., é and e) activate completely distinct representations. However, priming effects are reinstated for non-accented vowels (e.g., facil-FÁCIL < fecil-FÁCIL [easy in Spanish]). Here we tested the hypothesis that the lack of priming effects for primes containing accented vowels is a simple consequence of the saliency of the accent marks. To investigate this issue, we conducted a masked priming lexical decision experiment in which we minimized the saliency of the diacritical marks by using primes containing the letter i (i.e., a letter that contains itself a glyph over the letter). We manipulated prime-target visual similarity and the presence/absence of an accented vowel in the prime (e.g., obieto-OBJETO vs. obaeto-OBJETO; obíeto-OBJETO vs. obáeto-OBJETO [object in Spanish]). Results showed a sizeable visual similarity effect regardless of whether the prime was accented or not. Therefore, these findings suggest that, at least in scripts like Spanish, there is nothing special about the processing of accented vs. unaccented vowels once the saliency of the diacritical marks is reduced.

Transposed letter priming effects and allographic variation in Arabic: Insights from lexical decision and the same-different task

Reading is resilient to distortion of letter order within a word. This is evidenced in the “transposed-letter (TL) priming effect,” the finding that a prime generated by transposing adjacent letters in a word (e.g., jugde) facilitates recognition of the base word (e.g., JUDGE), more than a “substituted-letter” control prime in which the transposed letters are replaced by unrelated letters (e.g., junpe -JUDGE). The TL priming effect is well documented for European languages that are written using the Roman alphabet. Unlike these languages, Arabic has a unique position-dependent allography whereby some letters change shape according to their position within a word. We investigate the TL priming effect using a lexical decision (Experiment 1) and a same–different match task with Arabic words (Experiment 2) and nonwords (Experiment 3). No TL priming effects were found in Experiment 1, suggesting that the lexical-decision task engages lexical access processes that are sensitive to the Semitic nonlinear morphological structure. Experiments 2 and 3 revealed a robust TL priming effect overall. Nonallographic TL primes produced significantly larger facilitation than allographic TL primes, indicating that Arabic readers use allographic variation to resolve the uncertainty in letter order during the early stages of orthographic processing. The implication of these results for current letter position coding models is discussed.

Transposed-letter (TL) priming effects are popularly interpreted as reflecting noisy perception of letter order. The Arabic writing system has a unique allographic feature whereby a letter’s shape and letter spacing depend on its position within a word. We show that TL priming effects for Arabic words and nonwords are modulated by allography in the same–different task. It is important to consider which unique property of the language/writing system produces the cross-language variation, and how it does so.

From complexity to distinctiveness: The effect of expertise on letter perception

Fluent, adult readers of alphabetic languages encounter hundreds of millions of individual letters. What is the impact of such extensive experience on the perception and identification of letters? Recent evidence indicates that expert and naïve observers perceive letters differently. Here, we focus on the relationship between expertise and letter complexity (number of visual features) and distinctiveness (overlap in features with the other letters of the alphabet). Using a same-different letter judgement task, we examined the performance of individuals with high levels of expertise with Roman letters, but with different amounts of experience with the Arabic alphabet. The results reveal a trade-off between letter complexity and distinctiveness, such that while naïve individuals are sensitive only to letter complexity and not distinctiveness, the opposite is true for individuals with high expertise with an alphabet. These findings reveal a learning trajectory in which, with increasing experience, the influence of letter complexity is supplanted by distinctiveness, which requires an understanding of the relationship of each letter to the other possible letter shapes in the alphabet as a whole.

Is nevtral NEUTRAL? Visual similarity effects in the early phases of written-word recognition

For simplicity, contemporary models of written-word recognition and reading have unspecified feature/letter levels-they predict that the visually similar substituted-letter nonword PEQPLE is as effective at activating the word PEOPLE as the visually dissimilar substituted-letter nonword PEYPLE. Previous empirical evidence on the effects of visual similarly across letters during written-word recognition is scarce and nonconclusive. To examine whether visual similarity across letters plays a role early in word processing, we conducted two masked priming lexical decision experiments (stimulus-onset asynchrony = 50 ms). The substituted-letter primes were visually very similar to the target letters (u/v in Experiment 1 and i/j in Experiment 2; e.g., nevtral-NEUTRAL). For comparison purposes, we included an identity prime condition (neutral-NEUTRAL) and a dissimilar-letter prime condition (neztral-NEUTRAL). Results showed that the similar-letter prime condition produced faster word identification times than the dissimilar-letter prime condition. We discuss how models of written-word recognition should be amended to capture visual similarity effects across letters.

Does visual letter similarity modulate masked form priming in young readers of Arabic?

We carried out a masked priming lexical decision experiment to study whether visual letter similarity plays a role during the initial phases of word processing in young readers of Arabic (fifth graders). Arabic is ideally suited to test these effects because most Arabic letters share their basic shape with at least one other letter and differ only in the number/position of diacritical points (e.g., ض - ص ;ظ - ط ;غ - ع ;ث - ت - ن ب ;ذ - د ;خ - ح - ج ;ق - ف ;ش - س ;ز - ر). We created two one-letter-different priming conditions for each target word, in which a letter from the consonantal root was substituted by another letter that did or did not keep the same shape (e.g., خدمة - حدمة vs. خدمة - فدمة). Another goal of the current experiment was to test the presence of masked orthographic priming effects, which are thought to be unreliable in Semitic languages. To that end, we included an unrelated priming condition. We found a sizable masked orthographic priming effect relative to the unrelated condition regardless of visual letter similarity, thereby revealing that young readers are able to quickly process the diacritical points of Arabic letters. Furthermore, the presence of masked orthographic priming effects in Arabic suggests that the word identification stream in Indo-European and Semitic languages is more similar than previously thought.