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.

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

A crucial question in the domain of visual word recognition is whether letter similarity plays a role in the early stages of visual word processing. Here we focused on Arabic because in this language there are various groups of letters that share the same basic shape and only differ in the number/location of diacritical points. We conducted a masked priming lexical decision experiment in which a target word was preceded by: (i) an identity prime; (ii) a prime in which the critical letter was replaced by a letter with the same shape that differed in the number of diacritics (e.g., ); or (iii) a prime in which the critical letter was replaced by a letter with different shape (e.g., ). Results showed a sizable advantage of the identity condition over the two substituted-letter priming conditions (i.e., diacritical information is rapidly processed). Thus, diacritical marks play an essential role in the "feature letter" level of models of visual word recognition in Arabic.

Neural correlates of visual versus abstract letter processing in Roman and Arabic scripts.

In alphabetic orthographies, letter identification is a critical process during the recognition of visually presented words. In the present experiment, we examined whether and when visual form influences letter processing in two very distinct alphabets (Roman and Arabic). Disentangling visual versus abstract letter representations was possible because letters in the Roman alphabet may look visually similar/dissimilar in lowercase and uppercase forms (e.g., c-C vs. r-R) and letters in the Arabic alphabet may look visually similar/dissimilar, depending on their position within a word (e.g., [Formula: see text] - [Formula: see text] vs. [Formula: see text] - [Formula: see text]). We employed a masked priming same-different matching task while ERPs were measured from individuals who had learned the two alphabets at an early age. Results revealed a prime-target relatedness effect dependent on visual form in early components (P/N150) and a more abstract relatedness effect in a later component (P300). Importantly, the pattern of data was remarkably similar in the two alphabets. Thus, these data offer empirical support for a universal (i.e., across alphabets) hierarchical account of letter processing in which the time course of letter processing in different scripts follows a similar trajectory from visual features to visual form independent of abstract representations.

Priming of abstract letter representations may be universal: the case of Arabic.

Recent research on the Roman alphabet has demonstrated that the magnitudes of masked repetition priming are equivalent for letter pairs that have similar visual features across cases (e.g., c-C) and for letter pairs with dissimilar features (e.g., g-G). Here, we examined whether priming of abstract letter representations occurs in an orthographic system, Arabic, in which the letters show an intricate number of contextual forms. Arabic does not have a lowercase/uppercase distinction, but the letters exhibit different forms that depend on their position (initial, medial, final, or isolated) and their connectivity. Importantly, some letters look quite different across positions (e.g., (symbol in text) and (symbol in text), which correspond to the letter 'ayn), whereas others look very similar (e.g. (symbol in text), and (symbol in text), which correspond to the letter fa'). We employed a masked priming same-different task, in which native speakers of Arabic decided whether a target letter was the same as or different from a reference letter presented in a different position (middle vs. isolated). The results showed masked repetition priming effects of the same magnitude for letter pairs with similar and with dissimilar visual features across letter positions. These data support the view that priming of abstract letter representations is a universal phenomenon.

Physical similarity (and not quantity representation) drives perceptual comparison of numbers: evidence from two Indian notations.

Numerical quantity seems to affect the response in any task that involves numbers, even in tasks that do not demand access to quantity (e.g., perceptual tasks). That is, readers seem to activate quantity representations upon the mere presentation of integers. One important piece of evidence in favor of this view comes from the finding of a distance effect in perceptual tasks: When one compares two numbers, response times (RTs) are a function of the numerical distance between them. However, recent studies have suggested that the physical similarity between Arabic numbers is strongly correlated with their numerical distance, and that the former could be a better predictor of RT data in perceptual tasks in which magnitude processing is not required (Cohen, 2009a). The present study explored the Persian and Arabic versions of Indian numbers (Exps. 1 and 2, respectively). Naïve participants (speakers of Spanish) and users of these notations (Pakistanis and Jordanians) participated in a physical same-different matching task. The RTs of users of the Indian notations were regressed on perceptual similarity (estimated from the Spanish participants' RTs) and numerical distance. The results showed that, regardless of the degree of correlation between the perceptual similarity function and the numerical distance function, the critical predictor for RTs was perceptual similarity. Thus, participants do not automatically activate Indian integers' quantity representations, at least not when these numbers are presented in simple perceptual tasks.

Masked priming effects are modulated by expertise in the script.

In a recent study using a masked priming same-different matching task, Garci´a-Orza, Perea, and Munoz (2010) found a transposition priming effect for letter strings, digit strings, and symbol strings, but not for strings of pseudoletters (i.e., EPRI-ERPI produced similar response times to the control pair EDBI-ERPI). They argued that the mechanism responsible for position coding in masked priming is not operative with those "objects" whose identity cannot be attained rapidly. To assess this hypothesis, Experiment 1 examined masked priming effects in Arabic for native speakers of Arabic, whereas participants in Experiments 2 and 3 were lower intermediate learners of Arabic and readers with no knowledge of Arabic, respectively. Results showed a masked priming effect only for readers who are familiar with the Arabic script. Furthermore, transposed-letter priming in native speakers of Arabic only occurred when the order of the root letters was kept intact. In Experiments 3-7, we examined why masked repetition priming is absent for readers who are unfamiliar with the Arabic script. We discuss the implications of these findings for models of visual-word recognition.

The G428A nonsense mutation in FUT2 provides strong but not absolute protection against symptomatic GII.4 Norovirus infection.

In November 2004, 116 individuals in an elderly nursing home in El Grao de Castellón, Spain were symptomatically infected with genogroup II.4 (GII.4) norovirus. The global attack rate was 54.2%. Genotyping of 34 symptomatic individuals regarding the FUT2 gene revealed that one patient was, surprisingly, a non-secretor, hence indicating secretor-independent infection. Lewis genotyping revealed that Lewis-positive and negative individuals were susceptible to symptomatic norovirus infection indicating that Lewis status did not predict susceptibility. Saliva based ELISA assays were used to determine binding of the outbreak virus to saliva samples. Saliva from a secretor-negative individual bound the authentic outbreak GII.4 Valencia/2004/Es virus, but did not in contrast to secretor-positive saliva bind VLP of other strains including the GII.4 Dijon strain. Amino acid comparison of antigenic A and B sites located on the external loops of the P2 domain revealed distinct differences between the Valencia/2004/Es and Dijon strains. All three aa in each antigenic site as well as 10/11 recently identified evolutionary hot spots, were unique in the Valencia/2004/Es strain compared to the Dijon strain. To the best of our knowledge, this is the first example of symptomatic GII.4 norovirus infection of a Le(a+b-) individual homozygous for the G428A nonsense mutation in FUT2. Taken together, our study provides new insights into the host genetic susceptibility to norovirus infections and evolution of the globally dominating GII.4 viruses.

Sequential evolution of genotype GII.4 norovirus variants causing gastroenteritis outbreaks from 2001 to 2006 in Eastern Spain.

Noroviruses are the most common cause of outbreaks of viral gastroenteritis worldwide. Norovirus outbreaks were surveyed in Catalonia and the region of Valencia (Eastern Spain) between January 2001 and December 2006 as part of the European Union funded network "Food-borne viruses in Europe". During this time the etiology and epidemiological features of 194 outbreaks of acute non-bacterial gastroenteritis were investigated and norovirus was identified as causing 169 (87.1%) of them. Molecular epidemiology of viral strains was studied by RT-PCR and sequencing part of the RNA polymerase gene in ORF1 from 153 outbreak strains. The most commonly identified norovirus genotype was GII.4 (71.9% of the characterized outbreak strains), which is also the predominant genotype worldwide. During this survey five genetic variants of GII.4 genotype have been sequentially detected and identified as 1996, 2002, 2004, 2006a, and 2006b variants. The transition from one variant to a new one always took place over a short period of time, and thereafter the replacement of strains circulating previously was observed. These new GII.4 variants may have arisen as a consequence of viral evasion from the host immune responses, although apparently there is a lack of long-term immunity after norovirus infections.