Sascha Wolfer

An Eye Movement Study on the Role of the Visual Field Defect in Pure Alexia

Pure alexia is a severe impairment of word reading which is usually accompanied by a right-sided visual field defect. Patients with pure alexia exhibit better preserved writing and a considerable word length effect, claimed to result from a serial letter processing strategy. Two experiments compared the eye movements of four patients with pure alexia to controls with simulated visual field defects (sVFD) when reading single words. Besides differences in response times and differential effects of word length on word reading in both groups, fixation durations and the occurrence of a serial, letter-by-letter fixation strategy were investigated. The analyses revealed quantitative and qualitative differences between pure alexic patients and unimpaired individuals reading with sVFD. The patients with pure alexia read words slower and exhibited more fixations. The serial, letter-by-letter fixation strategy was observed only in the patients but not in the controls with sVFD. It is argued that the VFD does not cause pure alexic reading.

The statistical trade-off between word order and word structure – Large-scale evidence for the principle of least effort

Languages employ different strategies to transmit structural and grammatical information. While, for example, grammatical dependency relationships in sentences are mainly conveyed by the ordering of the words for languages like Mandarin Chinese, or Vietnamese, the word ordering is much less restricted for languages such as Inupiatun or Quechua, as these languages (also) use the internal structure of words (e.g. inflectional morphology) to mark grammatical relationships in a sentence. Based on a quantitative analysis of more than 1,500 unique translations of different books of the Bible in almost 1,200 different languages that are spoken as a native language by approximately 6 billion people (more than 80% of the world population), we present large-scale evidence for a statistical trade-off between the amount of information conveyed by the ordering of words and the amount of information conveyed by internal word structure: languages that rely more strongly on word order information tend to rely less on word structure information and vice versa. Or put differently, if less information is carried within the word, more information has to be spread among words in order to communicate successfully. In addition, we find that–despite differences in the way information is expressed–there is also evidence for a trade-off between different books of the biblical canon that recurs with little variation across languages: the more informative the word order of the book, the less informative its word structure and vice versa. We argue that this might suggest that, on the one hand, languages encode information in very different (but efficient) ways. On the other hand, content-related and stylistic features are statistically encoded in very similar ways.

Fast word reading in pure alexia: “fast, yet serial”

Pure alexia is a severe impairment of word reading in which individuals process letters serially with a pronounced length effect. Yet, there is considerable variation in the performance of alexic readers with generally very slow, but also occasionally fast responses, an observation addressed rarely in previous reports. It has been suggested that “fast” responses in pure alexia reflect residual parallel letter processing or that they may even be subserved by an independent reading system. Four experiments assessed fast and slow reading in a participant (DN) with pure alexia. Two behavioral experiments investigated frequency, neighborhood, and length effects in forced fast reading. Two further experiments measured eye movements when DN was forced to read quickly, or could respond faster because words were easier to process. Taken together, there was little support for the proposal that “qualitatively different” mechanisms or reading strategies underlie both types of responses in DN. Instead, fast responses are argued to be generated by the same serial-reading strategy.

Vernetzungsstrukturen digitaler Wörterbücher. Neue Ansätze zur Analyse / Cross-linking structures of digital dictionaries. New approaches for analysis / La structure des liens croisés dans les dictionnaires électroniques

Abstract In this contribution, we present a novel approach for the analysis of cross-reference structures in digital dictionaries on the basis of the complete dictionary database. Using paradigmatic items in the German Wiktionary as an example, we show how analyses based on graph theory can be fruitfully applied in this context, e. g. to gain an overview of paradigmatic references as a whole or to detect closely connected groups of headwords. Furthermore, we connect information about cross-reference structures with corpus frequencies and log file statistics. In this way, we can answer questions such as the following ones: Are frequent words paradigmatically linked more closely than others? Are closely linked headwords or headwords that stand more solitary in the dictionary visited significantly more often?