The development of orthographic and phonological representations in relation to linguistic transparency in Greek and English (L2)

The development of orthographic as well as phonological representations as a result of the functions of each language’s level of transparency is the main focus of the present work. Initially, a review of the relevant literature is presented with the most prominent theories behind the development of representations being introduced and critiqued. Furthermore, two experiments were conducted to investigate the relative contributions of orthography and phonology as well as of different size units in word recognition. Ten Greek subjects (n=10) with mean age of approximately 15 years and mean reading age in English of approximately 11 years participated and were tested in reading words and non-words in their native language and in English (L2). The nonsense words utilized either shared orthography and phonology, phonology only, or neither of the two with real words at the level of the rime. Analysis showed that the participants benefitted both from orthographic and phonological facilitation in terms of speed in both their native (transparent) and foreign language (non-transparent). They also showed an accuracy deficit when the cues were not present in the English stimuli but not in the Greek ones. These results are interpreted with respect to the differences that the level of transparency and the maturity of the reading skills can introduce in the development of the mental representations employed in word recognition

Mechanisms of stress assignment in Greek and English skilled reading

Assignment of lexical stress to the appropriate syllable is an integral part of reading polysyllabic words. The attention of reading research and computational modelling of reading has recently shifted from the monosyllabic to the polysyllabic domain, hence making more apparent the need to understand the stress assignment process. The great amount of cross-linguistic variability regarding the type and the amount of information that each language provides to its readers about stress position indicates that the stress assignment mechanism is not a uniform process among different languages. Research on the stress assignment mechanism investigates how diverse sources of information on stress position in each language interact with and shape the process of assigning stress to polysyllabic words. The main focus of this thesis was to enhance theoretical knowledge regarding stress assignment by collecting and analysing data in two languages with quite distinct linguistic characteristics regarding stress, namely, Greek and English. The sources of information on stress position can be generally summarised in lexical contributions by access to the stored position of stress for each word in the mental representations, the explicit indication of stress position by orthographic stress marks, and language-dependent statistical regularities between orthography and/or phonology and stress position. In Greek, stress position is explicitly and consistently marked orthographically by means of a diacritic over the vowel of the stressed syllable but only in lower and not uppercase words. Hence, it provides an ideal platform for investigations with naturalistic manipulations of the availability of this information through manipulation of case. A default metrical bias to stress a specific syllable, the prefinal, has also been observed. With the utilisation of reading aloud and lexical decision experiments, it was investigated: 1) how the different sources of information interact with each other; 2) how the shift in reading strategies has an impact on this mechanism; and 3) within the framework of a computationally implemented theory of reading, what levels of representation stress is encoded at. Experiments with Greek skilled readers in reading aloud showed that the stress assignment mechanism is directly dependent upon shifts of processing strategies in reading with lexical processing encouraging the extraction of stress position information directly from the lexicon. The default bias was also found to be active and dominant in the absence of other sources but also of relatively limited contributions when the other sources are present. Effects of case type of presentation were also disentangled from any potential effects from the availability of the diacritics. Case type was found to have an independent role in reading regardless whether this coincides with the presence of stress marks (in lowercase) or not (in uppercase). Experiments with skilled readers in visual word recognition showed evidence that stress is a multifaceted feature encoded in several levels of representation in the reading system, including as an independent unit processed at the letter level, stored in the phonological representations, and embedded in the orthographic representations of known words. Additionally, statistical analyses of the statistical characteristics of Greek orthography, which eventually led to the development of a new psycholinguistic database (Kyparissiadis, van Heuven, Pitchford & Ledgeway, 2017), showed that, in similarity with other languages such as English, the orthographic patterns in the endings of Greek words can be associated with specific stress positions. It remains to be investigated whether such regularities have a behavioural dimension and inform the stress mechanism as an additional source of information on stress assignment. This has been shown in other languages that present similar regularities. Furthermore, it was shown that the default metrical bias, which has universally been accounted as the result of a statistical preponderance of stress on a specific syllable, does not present a uniform statistical dominance in Greek. The process of adding part-of-speech information to the database elucidated that not all grammatical categories are predominantly stressed on the default position. In contrast to other languages, in which readers have been shown to be sensitive to the shift of statistical regularities within different subsets of the language’s battery, a lexical decision experiment in Greek showed uniform conformance of readers to the default bias even in a subset or words that does not present this statistical dominance. This raises questions regarding the origins of the default bias and warrants further investigations. In English, in conjunction to lexical retrieval, stress assignment is argued to be heavily affected by associations between orthography and the stressed syllable. Investigations on the default metrical bias in English have given rise to inconsistent results. Direct comparison of the contributions of the default mechanism against lexical activations in stress assignment showed no evidence for a default pattern being active in English reading in the presence of lexical information. However, the shifting of stressing strategies induced by a subsequent implicit priming experiment suggests that stress assignment through lexical access can be still affected by sublexical processes. Computational simulations with a leading computational model of reading showed a heavier reliance of the model on lexical contributions rather than orthographic information when these two sources where contrasted against each other. However, the model showed sub-optimal performance when simulating the behavioural results of the first experiment in English reported above. The reasons behind this inefficiency of a model that is able to simulate a wide range of behavioural patterns are considered and discussed. Finally, results of simulations from a preliminary word recognition model in Greek are presented and future directions for these modelling investigations are discussed. Overall, the results of this body of research indicate the stress assignment mechanism is multi-facetted and language-dependent. This has implications for universal models of written word recognition and reading aloud that future research will need to address

GreekLex 2: a comprehensive lexical database with part-of-speech, syllabic, phonological, and stress information

Databases containing lexical properties on any given orthography are crucial for psycholinguistic research. In the last ten years, a number of lexical databases have been developed for Greek. However, these lack important part-of-speech information. Furthermore, the need for alternative procedures for calculating syllabic measurements and stress information, as well as combination of several metrics to investigate linguistic properties of the Greek language are highlighted. To address these issues, we present a new extensive lexical database of Modern Greek (GreekLex 2) with part-of-speech information for each word and accurate syllabification and orthographic information predictive of stress, as well as several measurements of word similarity and phonetic information. The addition of detailed statistical information about Greek part-of-speech, syllabification, and stress neighbourhood allowed novel analyses of stress distribution within different grammatical categories and syllabic lengths to be carried out. Results showed that the statistical preponderance of stress position on the pre-final syllable that is reported for Greek language is dependent upon grammatical category. Additionally, analyses showed that a proportion higher than 90% of the tokens in the database would be stressed correctly solely by relying on stress neighbourhood information. The database and the scripts for orthographic and phonological syllabification as well as phonetic transcription are available at http://www.psychology.nottingham.ac.uk/greeklex/

Mechanisms of stress assignment in Greek and English skilled reading

Assignment of lexical stress to the appropriate syllable is an integral part of reading polysyllabic words. The attention of reading research and computational modelling of reading has recently shifted from the monosyllabic to the polysyllabic domain, hence making more apparent the need to understand the stress assignment process. The great amount of cross-linguistic variability regarding the type and the amount of information that each language provides to its readers about stress position indicates that the stress assignment mechanism is not a uniform process among different languages. Research on the stress assignment mechanism investigates how diverse sources of information on stress position in each language interact with and shape the process of assigning stress to polysyllabic words. The main focus of this thesis was to enhance theoretical knowledge regarding stress assignment by collecting and analysing data in two languages with quite distinct linguistic characteristics regarding stress, namely, Greek and English. The sources of information on stress position can be generally summarised in lexical contributions by access to the stored position of stress for each word in the mental representations, the explicit indication of stress position by orthographic stress marks, and language-dependent statistical regularities between orthography and/or phonology and stress position. In Greek, stress position is explicitly and consistently marked orthographically by means of a diacritic over the vowel of the stressed syllable but only in lower and not uppercase words. Hence, it provides an ideal platform for investigations with naturalistic manipulations of the availability of this information through manipulation of case. A default metrical bias to stress a specific syllable, the prefinal, has also been observed. With the utilisation of reading aloud and lexical decision experiments, it was investigated: 1) how the different sources of information interact with each other; 2) how the shift in reading strategies has an impact on this mechanism; and 3) within the framework of a computationally implemented theory of reading, what levels of representation stress is encoded at. Experiments with Greek skilled readers in reading aloud showed that the stress assignment mechanism is directly dependent upon shifts of processing strategies in reading with lexical processing encouraging the extraction of stress position information directly from the lexicon. The default bias was also found to be active and dominant in the absence of other sources but also of relatively limited contributions when the other sources are present. Effects of case type of presentation were also disentangled from any potential effects from the availability of the diacritics. Case type was found to have an independent role in reading regardless whether this coincides with the presence of stress marks (in lowercase) or not (in uppercase). Experiments with skilled readers in visual word recognition showed evidence that stress is a multifaceted feature encoded in several levels of representation in the reading system, including as an independent unit processed at the letter level, stored in the phonological representations, and embedded in the orthographic representations of known words. Additionally, statistical analyses of the statistical characteristics of Greek orthography, which eventually led to the development of a new psycholinguistic database (Kyparissiadis, van Heuven, Pitchford & Ledgeway, 2017), showed that, in similarity with other languages such as English, the orthographic patterns in the endings of Greek words can be associated with specific stress positions. It remains to be investigated whether such regularities have a behavioural dimension and inform the stress mechanism as an additional source of information on stress assignment. This has been shown in other languages that present similar regularities. Furthermore, it was shown that the default metrical bias, which has universally been accounted as the result of a statistical preponderance of stress on a specific syllable, does not present a uniform statistical dominance in Greek. The process of adding part-of-speech information to the database elucidated that not all grammatical categories are predominantly stressed on the default position. In contrast to other languages, in which readers have been shown to be sensitive to the shift of statistical regularities within different subsets of the language’s battery, a lexical decision experiment in Greek showed uniform conformance of readers to the default bias even in a subset or words that does not present this statistical dominance. This raises questions regarding the origins of the default bias and warrants further investigations. In English, in conjunction to lexical retrieval, stress assignment is argued to be heavily affected by associations between orthography and the stressed syllable. Investigations on the default metrical bias in English have given rise to inconsistent results. Direct comparison of the contributions of the default mechanism against lexical activations in stress assignment showed no evidence for a default pattern being active in English reading in the presence of lexical information. However, the shifting of stressing strategies induced by a subsequent implicit priming experiment suggests that stress assignment through lexical access can be still affected by sublexical processes. Computational simulations with a leading computational model of reading showed a heavier reliance of the model on lexical contributions rather than orthographic information when these two sources where contrasted against each other. However, the model showed sub-optimal performance when simulating the behavioural results of the first experiment in English reported above. The reasons behind this inefficiency of a model that is able to simulate a wide range of behavioural patterns are considered and discussed. Finally, results of simulations from a preliminary word recognition model in Greek are presented and future directions for these modelling investigations are discussed. Overall, the results of this body of research indicate the stress assignment mechanism is multi-facetted and language-dependent. This has implications for universal models of written word recognition and reading aloud that future research will need to address

The development of orthographic and phonological representations in relation to linguistic transparency in Greek and English (L2)

The development of orthographic as well as phonological representations as a result of the functions of each language’s level of transparency is the main focus of the present work. Initially, a review of the relevant literature is presented with the most prominent theories behind the development of representations being introduced and critiqued. Furthermore, two experiments were conducted to investigate the relative contributions of orthography and phonology as well as of different size units in word recognition. Ten Greek subjects (n=10) with mean age of approximately 15 years and mean reading age in English of approximately 11 years participated and were tested in reading words and non-words in their native language and in English (L2). The nonsense words utilized either shared orthography and phonology, phonology only, or neither of the two with real words at the level of the rime. Analysis showed that the participants benefitted both from orthographic and phonological facilitation in terms of speed in both their native (transparent) and foreign language (non-transparent). They also showed an accuracy deficit when the cues were not present in the English stimuli but not in the Greek ones. These results are interpreted with respect to the differences that the level of transparency and the maturity of the reading skills can introduce in the development of the mental representations employed in word recognition

Consonant-type classification.

<p>Consonant types were classified according to the Manner of Articulation, Place of Articulation, and Voicing scales.</p

Orthographic similarity as a function of length.

<p>Distributions of mean OLD20 Levenshtein Distance (based on [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172493#pone.0172493.ref009" target="_blank">9</a>]) and Coltheart’s N orthographic similarity (based on [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172493#pone.0172493.ref008" target="_blank">8</a>]) as a function of word length measured in letters.</p

Distribution of stress position by part-of-speech category.

<p>Counts for disyllables (3A), trisyllables (3B), and all polysyllables (3C). Only adjectives, nouns and verbs were considered for these calculations.</p

Frequency of N (Neighbourhood) counts.

<p>Frequency counts for the clustered OLD20 Levenshtein Distance (based on [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172493#pone.0172493.ref009" target="_blank">9</a>]) values and Coltheart’s N orthographic similarity (based on [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0172493#pone.0172493.ref008" target="_blank">8</a>]) values. OLD20 values are clustered around their closest integer numbers (e.g. a value of 2 represents the counts of all values between 1.5 and 2.49). Coltheart’s N values above 10 are not presented in the graph as they accumulatively represent a proportion smaller than 0.5% of the whole set.</p

Distribution of stress position by number of syllables.

<p>Distribution of stress position by types (2A) and tokens (2B). Syllabic lengths higher than 7 (up to 11) were not presented in the graph as they accumulatively represent a proportion less than 1% (types) and 0.1% (tokens) of the whole set.</p