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Previous research has shown that high phonotactic frequencies
facilitate the production of regularly inflected verbs in English-learning
children with specific language impairment (SLI) but not with typical
development (TD). We asked whether this finding can be replicated
for German, a language with a much more complex inflectional
verb paradigm than English. Using an elicitation task, the production
of inflected nonce verb forms (3 rd person singular with -t suffix)
with either high- or low-frequency subsyllables was tested in
sixteen German-learning children with SLI (ages 4;1–5 ;1), sixteen
TD-children matched for chronological age (CA) and fourteen TD-
children matched for verbal age (VA) (ages 3;0–3 ;11). The findings
revealed that children with SLI, but not CA- or VA-children, showed
differential performance between the two types of verbs, producing
more inflectional errors when the verb forms resulted in low-frequency
subsyllables than when they resulted in high-frequency subsyllables,
replicating the results from English-learning children.
Previous research has shown that high phonotactic frequencies facilitate the production of regularly inflected verbs in English-learning children with specific language impairment (SLI) but not with typical development (TD). We asked whether this finding can be replicated for German, a language with a much more complex inflectional verb paradigm than English. Using an elicitation task, the production of inflected nonce verb forms (3rd person singular with - t suffix) with either high-or low-frequency subsyllables was tested in sixteen German-learning children with SLI (ages 4;1-5;1), sixteen TD-children matched for chronological age (CA) and fourteen TD-children matched for verbal age (VA) (ages 3;0-3;11). The findings revealed that children with SLI, but not CA-or VA-children, showed differential performance between the two types of verbs, producing more inflectional errors when the verb forms resulted in low-frequency subsyllables than when they resulted in high-frequency subsyllables, replicating the results from English-learning children.
This study examines the processing of morphologically complex words focusing on how morphological (in addition to orthographic and semantic) factors affect bilingual word recognition. We report findings from a large experimental study with groups of bilingual (Turkish/German) speakers using the visual masked-priming technique. We found morphologically mediated effects on the response speed and the inter-individual variability within the bilingual participant group. We conclude that the grammar (qua morphological parsing) not only enhances speed of processing in bilingual language processing but also yields more uniform performance and thereby constrains variability within a group of otherwise heterogeneous individuals.
Word forms such as walked or walker are decomposed into their morphological constituents (walk + -ed/-er) during language comprehension. Yet, the efficiency of morphological decomposition seems to vary for different languages and morphological types, as well as for first and second language speakers. The current study reports results from a visual masked priming experiment focusing on different types of derived word forms (specifically prefixed vs. suffixed) in first and second language speakers of German. We compared the present findings with results from previous studies on inflection and compounding and proposed an account of morphological decomposition that captures both the variability and the consistency of morphological decomposition for different morphological types and for first and second language speakers. Open Practices This article has been awarded an Open Materials badge. Study materials are publicly accessible via the Open Science Framework at . Learn more about the Open Practices badges from the Center for Open Science: .
Word forms such as walked or walker are decomposed into their morphological constituents (walk + -ed/-er) during language comprehension. Yet, the efficiency of morphological decomposition seems to vary for different languages and morphological types, as well as for first and second language speakers. The current study reports results from a visual masked priming experiment focusing on different types of derived word forms (specifically prefixed vs. suffixed) in first and second language speakers of German. We compared the present findings with results from previous studies on inflection and compounding and proposed an account of morphological decomposition that captures both the variability and the consistency of morphological decomposition for different morphological types and for first and second language speakers. Open Practices This article has been awarded an Open Materials badge. Study materials are publicly accessible via the Open Science Framework at . Learn more about the Open Practices badges from the Center for Open Science.
Salt marshes filter pollutants, protect coastlines against storm surges, and sequester carbon, yet are under threat from sea level rise and anthropogenic modification. The sustained existence of the salt marsh ecosystem depends on the topographic evolution of marsh platforms. Quantifying marsh platform topography is vital for improving the management of these valuable landscapes. The determination of platform boundaries currently relies on supervised classification methods requiring near-infrared data to detect vegetation, or demands labour-intensive field surveys and digitisation. We propose a novel, unsupervised method to reproducibly isolate salt marsh scarps and platforms from a digital elevation model (DEM), referred to as Topographic Identification of Platforms (TIP). Field observations and numerical models show that salt marshes mature into subhorizontal platforms delineated by subvertical scarps. Based on this premise, we identify scarps as lines of local maxima on a slope raster, then fill landmasses from the scarps upward, thus isolating mature marsh platforms. We test the TIP method using lidar-derived DEMs from six salt marshes in England with varying tidal ranges and geometries, for which topographic platforms were manually isolated from tidal flats. Agreement between manual and unsupervised classification exceeds 94% for DEM resolutions of 1 m, with all but one site maintaining an accuracy superior to 90% for resolutions up to 3 m. For resolutions of 1 m, platforms detected with the TIP method are comparable in surface area to digitised platforms and have similar elevation distributions. We also find that our method allows for the accurate detection of local block failures as small as 3 times the DEM resolution. Detailed inspection reveals that although tidal creeks were digitised as part of the marsh platform, unsupervised classification categorises them as part of the tidal flat, causing an increase in false negatives and overall platform perimeter. This suggests our method may benefit from combination with existing creek detection algorithms. Fallen blocks and high tidal flat portions, associated with potential pioneer zones, can also lead to differences between our method and supervised mapping. Although pioneer zones prove difficult to classify using a topographic method, we suggest that these transition areas should be considered when analysing erosion and accretion processes, particularly in the case of incipient marsh platforms. Ultimately, we have shown that unsupervised classification of marsh platforms from high-resolution topography is possible and sufficient to monitor and analyse topographic evolution.
For many years, psycholinguistic evidence has been predominantly based on findings from native speakers of Indo-European languages, primarily English, thus providing a rather limited perspective into the human language system. In recent years a growing body of experimental research has been devoted to broadening this picture, testing a wide range of speakers and languages, aiming to understanding the factors that lead to variability in linguistic performance. The present dissertation investigates sources of variability within the morphological domain, examining how and to what extent morphological processes and representations are shaped by specific properties of languages and speakers. Firstly, the present work focuses on a less explored language, Hebrew, to investigate how the unique non-concatenative morphological structure of Hebrew, namely a non-linear combination of consonantal roots and vowel patterns to form lexical entries (L-M-D + CiCeC = limed ‘teach’), affects morphological processes and representations in the Hebrew lexicon. Secondly, a less investigated population was tested: late learners of a second language. We directly compare native (L1) and non-native (L2) speakers, specifically highly proficient and immersed late learners of Hebrew. Throughout all publications, we have focused on a morphological phenomenon of inflectional classes (called binyanim; singular: binyan), comparing productive (class Piel, e.g., limed ‘teach’) and unproductive (class Paal, e.g., lamad ‘learn’) verbal inflectional classes. By using this test case, two psycholinguistic aspects of morphology were examined: (i) how morphological structure affects online recognition of complex words, using masked priming (Publications I and II) and cross-modal priming (Publication III) techniques, and (ii) what type of cues are used when extending morpho-phonological patterns to novel complex forms, a process referred to as morphological generalization, using an elicited production task (Publication IV).
The findings obtained in the four manuscripts, either published or under review, provide significant insights into the role of productivity in Hebrew morphological processing and generalization in L1 and L2 speakers. Firstly, the present L1 data revealed a close relationship between productivity of Hebrew verbal classes and recognition process, as revealed in both priming techniques. The consonantal root was accessed only in the productive class (Piel) but not the unproductive class (Paal). Another dissociation between the two classes was revealed in the cross-modal priming, yielding a semantic relatedness effect only for Paal but not Piel primes. These findings are taken to reflect that the Hebrew mental representations display a balance between stored undecomposable unstructured stems (Paal) and decomposed structured stems (Piel), in a similar manner to a typical dual-route architecture, showing that the Hebrew mental lexicon is less unique than previously claimed in psycholinguistic research. The results of the generalization study, however, indicate that there are still substantial differences between inflectional classes of Hebrew and other Indo-European classes, particularly in the type of information they rely on in generalization to novel forms. Hebrew binyan generalization relies more on cues of argument structure and less on phonological cues.
Secondly, clear L1/L2 differences were observed in the sensitivity to abstract morphological and morpho-syntactic information during complex word recognition and generalization. While L1 Hebrew speakers were sensitive to the binyan information during recognition, expressed by the contrast in root priming, L2 speakers showed similar root priming effects for both classes, but only when the primes were presented in an infinitive form. A root priming effect was not obtained for primes in a finite form. These patterns are interpreted as evidence for a reduced sensitivity of L2 speakers to morphological information, such as information about inflectional classes, and evidence for processing costs in recognition of forms carrying complex morpho-syntactic information. Reduced reliance on structural information cues was found in production of novel verbal forms, when the L2 group displayed a weaker effect of argument structure for Piel responses, in comparison to the L1 group. Given the L2 results, we suggest that morphological and morphosyntactic information remains challenging for late bilinguals, even at high proficiency levels.
Do properties of individual languages shape the mechanisms by which they are processed? By virtue of their non-concatenative morphological structure, the recognition of complex words in Semitic languages has been argued to rely strongly on morphological information and on decomposition into root and pattern constituents. Here, we report results from a masked priming experiment in Hebrew in which we contrasted verb forms belonging to two morphological classes, Paal and Piel, which display similar properties, but crucially differ on whether they are extended to novel verbs. Verbs from the open-class Piel elicited familiar root priming effects, but verbs from the closed-class Paal did not. Our findings indicate that, similarly to other (e.g., Indo-European) languages, down-to-the-root decomposition in Hebrew does not apply to stems of non-productive verbal classes. We conclude that the Semitic word processor is less unique than previously thought: Although it operates on morphological units that are combined in a non-linear way, it engages the same universal mechanisms of storage and computation as those seen in other languages.
Do properties of individual languages shape the mechanisms by which they are processed? By virtue of their non-concatenative morphological structure, the recognition of complex words in Semitic languages has been argued to rely strongly on morphological information and on decomposition into root and pattern constituents. Here, we report results from a masked priming experiment in Hebrew in which we contrasted verb forms belonging to two morphological classes, Paal and Piel, which display similar properties, but crucially differ on whether they are extended to novel verbs. Verbs from the open-class Piel elicited familiar root priming effects, but verbs from the closed-class Paal did not. Our findings indicate that, similarly to other (e.g., Indo-European) languages, down-to-the-root decomposition in Hebrew does not apply to stems of non-productive verbal classes. We conclude that the Semitic word processor is less unique than previously thought: Although it operates on morphological units that are combined in a non-linear way, it engages the same universal mechanisms of storage and computation as those seen in other languages.
The aim of this thesis is to achieve a deep understanding of the working mechanism of polymer based solar cells and to improve the device performance. Two types of the polymer based solar cells are studied here: all-polymer solar cells comprising macromolecular donors and acceptors based on poly(p-phenylene vinylene) and hybrid cells comprising a PPV copolymer in combination with a novel small molecule electron acceptor. To understand the interplay between morphology and photovoltaic properties in all-polymer devices, I compared the photocurrent characteristics and excited state properties of bilayer and blend devices with different nano-morphology, which was fine tuned by using solvents with different boiling points. The main conclusion from these complementary measurements was that the performance-limiting step is the field-dependent generation of free charge carriers, while bimolecular recombination and charge extraction do not compromise device performance. These findings imply that the proper design of the donor-acceptor heterojunction is of major importance towards the goal of high photovoltaic efficiencies. Regarding polymer-small molecular hybrid solar cells I combined the hole-transporting polymer M3EH-PPV with a novel Vinazene-based electron acceptor. This molecule can be either deposited from solution or by thermal evaporation, allowing for a large variety of layer architectures to be realized. I then demonstrated that the layer architecture has a large influence on the photovoltaic properties. Solar cells with very high fill factors of up to 57 % and an open circuit voltage of 1V could be achieved by realizing a sharp and well-defined donor-acceptor heterojunction. In the past, fill factors exceeding 50 % have only been observed for polymers in combination with soluble fullerene-derivatives or nanocrystalline inorganic semiconductors as the electron-accepting component. The finding that proper processing of polymer-vinazene devices leads to similar high values is a major step towards the design of efficient polymer-based solar cells.