Universitätspublikationen
Refine
Document Type
- Article (5)
- Working Paper (2)
- Conference Proceeding (1)
- Doctoral Thesis (1)
Language
- English (9) (remove)
Has Fulltext
- yes (9) (remove)
Is part of the Bibliography
- no (9)
Keywords
- Semantics (9) (remove)
Institute
Abstract: The human visual cortex enables visual perception through a cascade of hierarchical computations in cortical regions with distinct functionalities. Here, we introduce an AI-driven approach to discover the functional mapping of the visual cortex. We related human brain responses to scene images measured with functional MRI (fMRI) systematically to a diverse set of deep neural networks (DNNs) optimized to perform different scene perception tasks. We found a structured mapping between DNN tasks and brain regions along the ventral and dorsal visual streams. Low-level visual tasks mapped onto early brain regions, 3-dimensional scene perception tasks mapped onto the dorsal stream, and semantic tasks mapped onto the ventral stream. This mapping was of high fidelity, with more than 60% of the explainable variance in nine key regions being explained. Together, our results provide a novel functional mapping of the human visual cortex and demonstrate the power of the computational approach.
Author Summary: Human visual perception is a complex cognitive feat known to be mediated by distinct cortical regions of the brain. However, the exact function of these regions remains unknown, and thus it remains unclear how those regions together orchestrate visual perception. Here, we apply an AI-driven brain mapping approach to reveal visual brain function. This approach integrates multiple artificial deep neural networks trained on a diverse set of functions with functional recordings of the whole human brain. Our results reveal a systematic tiling of visual cortex by mapping regions to particular functions of the deep networks. Together this constitutes a comprehensive account of the functions of the distinct cortical regions of the brain that mediate human visual perception.
This thesis investigates the acquisition of compositional and lexical semantic properties of adjectives in German-speaking children between the age of two and five years.
According to formal semantic approaches, there are intersective and non-intersective adjectives, subsective and non-subsective adjectives as well as gradable and non-gradable adjectives. These properties concern the compositional mechanisms involved in nominal modification, i.e., the combination of adjectives and nouns. In addition, adjectives differ regarding lexical semantic properties that contribute to the adjectives' meaning. Differences in the adjectives' scale structure have led to the theoretical assumption that gradable adjectives should be distinguished into relative and absolute gradable adjectives. In addition, meaning components such as multidimensionality or subjectivity have led to the distinction between dimensional and evaluative gradable adjectives. These properties have been mostly investigated independently of each other in both theory and acquisition research. I suggest a classification system for adjectives that combines different semantic properties. This system results in six adjective classes constituting a Semantic Complexity Hierarchy. Assuming that these adjective classes differ in semantic complexity, I propose an operationalization of semantic complexity that takes into account the adjectives' length of description, their type complexity, and lexical properties that contribute to the adjectives' meaning.
Regarding the question of how monolingual German-speaking children acquire the semantics of adjectives, I hypothesize that the order of acquisition of adjectives is determined by their semantic complexity. This hypothesis is tested in a spontaneous speech study and a comprehension experiment.
The spontaneous speech study is a longitudinal investigation of the production of adjectives from 2;00 to 2;11 years based on transcripts from a dense data corpus. The results provide evidence that the mean age of acquisition for the adjective classes in the Semantic Complexity Hierarchy follows the order predicted by semantic complexity. The same order was observed for the age at which the number of types for each class increased most. A preliminary analysis of the input indicates that the frequency of parental adjective use is related to the order of acquisition, but it is unlikely that frequency determines the order completely.
The comprehension experiment focuses on two specific adjective classes. I examine children's and adults' interpretation of relative (big, small) and absolute (clean, dirty) gradable dimensional adjectives with a picture-choice task. These two classes are of the same semantic complexity because they are both gradable, but they have different scale structures. As a result, they must be interpreted differently due to lexical semantic properties. I investigate whether children calculate different standards of comparison for relative and absolute gradable adjectives and whether they distinguish between relative and absolute gradable adjectives regarding the relevance of the explicit comparison class. The results indicate that as of age 3, children distinguish between relative and absolute gradable adjectives with regard to the standard of comparison. However, with respect to the relevance of the comparison class, for 3-year-old children, unlike for 4- and 5-year-olds, changes in the noun, i.e., in the explicit comparison class, led to non-adult-like responses regarding both relative and absolute gradable adjectives.
On the basis of the empirical findings, I propose an acquisition path stating that children enter the acquisition process with inherent linguistic knowledge, the Semantic Complexity Hierarchy, and cognitive abilities to categorize their environment. I suggest that initially, children apply the least complex interpretation available in the Semantic Complexity Hierarchy to all adjectives: all adjectives are interpreted as properties of individuals that are not gradable. To access other levels of the Semantic Complexity Hierarchy and to establish more complex adjective classes, positive evidence from the input and conceptual properties of adjectives, e.g., COLOR, MENTAL STATE, PHYSICAL PROPERTY etc., can operate as triggers.
The correspondence between the terminology used for querying and the one used in content objects to be retrieved, is a crucial prerequisite for effective retrieval technology. However, as terminology is evolving over time, a growing gap opens up between older documents in (long-term) archives and the active language used for querying such archives. Thus, technologies for detecting and systematically handling terminology evolution are required to ensure "semantic" accessibility of (Web) archive content on the long run. As a starting point for dealing with terminology evolution this paper formalizes the problem and discusses issues, first ideas and relevant technologies.
Switching between reading tasks leads to phase-transitions in reading times in L1 and L2 readers
(2019)
Reading research uses different tasks to investigate different levels of the reading process, such as word recognition, syntactic parsing, or semantic integration. It seems to be tacitly assumed that the underlying cognitive process that constitute reading are stable across those tasks. However, nothing is known about what happens when readers switch from one reading task to another. The stability assumptions of the reading process suggest that the cognitive system resolves this switching between two tasks quickly. Here, we present an alternative language-game hypothesis (LGH) of reading that begins by treating reading as a softly-assembled process and that assumes, instead of stability, context-sensitive flexibility of the reading process. LGH predicts that switching between two reading tasks leads to longer lasting phase-transition like patterns in the reading process. Using the nonlinear-dynamical tool of recurrence quantification analysis, we test these predictions by examining series of individual word reading times in self-paced reading tasks where native (L1) and second language readers (L2) transition between random word and ordered text reading tasks. We find consistent evidence for phase-transitions in the reading times when readers switch from ordered text to random-word reading, but we find mixed evidence when readers transition from random-word to ordered-text reading. In the latter case, L2 readers show moderately stronger signs for phase-transitions compared to L1 readers, suggesting that familiarity with a language influences whether and how such transitions occur. The results provide evidence for LGH and suggest that the cognitive processes underlying reading are not fully stable across tasks but exhibit soft-assembly in the interaction between task and reader characteristics.
A logical framework consisting of a polymorphic call-by-value functional language and a first-order logic on the values is presented, which is a reconstruction of the logic of the verification system VeriFun. The reconstruction uses contextual semantics to define the logical value of equations. It equates undefinedness and non-termination, which is a standard semantical approach. The main results of this paper are: Meta-theorems about the globality of several classes of theorems in the logic, and proofs of global correctness of transformations and deduction rules. The deduction rules of VeriFun are globally correct if rules depending on termination are appropriately formulated. The reconstruction also gives hints on generalizations of the VeriFun framework: reasoning on nonterminating expressions and functions, mutual recursive functions and abstractions in the data values, and formulas with arbitrary quantifier prefix could be allowed.
We tested the hypothesis that phonosemantic iconicity––i.e., a motivated resonance of sound and meaning––might not only be found on the level of individual words or entire texts, but also in word combinations such that the meaning of a target word is iconically expressed, or highlighted, in the phonetic properties of its immediate verbal context. To this end, we extracted single lines from German poems that all include a word designating high or low dominance, such as large or small, strong or weak, etc. Based on insights from previous studies, we expected to find more vowels with a relatively short distance between the first two formants (low formant dispersion) in the immediate context of words expressing high physical or social dominance than in the context of words expressing low dominance. Our findings support this hypothesis, suggesting that neighboring words can form iconic dyads in which the meaning of one word is sound-iconically reflected in the phonetic properties of adjacent words. The construct of a contiguity-based phono-semantic iconicity opens many venues for future research well beyond lines extracted from poems.
Beauty is the single most frequently and most broadly used aesthetic virtue term. The present study aimed at providing higher conceptual resolution to the broader notion of beauty by comparing it with three closely related aesthetically evaluative concepts which are likewise lexicalized across many languages: elegance, grace(fulness), and sexiness. We administered a variety of questionnaires that targeted perceptual qualia, cognitive and affective evaluations, as well as specific object properties that are associated with beauty, elegance, grace, and sexiness in personal looks, movements, objects of design, and other domains. This allowed us to reveal distinct and highly nuanced profiles of how a beautiful, elegant, graceful, and sexy appearance is subjectively perceived. As aesthetics is all about nuances, the fine-grained conceptual analysis of the four target concepts of our study provides crucial distinctions for future research.
Plants, fungi and algae are important components of global biodiversity and are fundamental to all ecosystems. They are the basis for human well-being, providing food, materials and medicines. Specimens of all three groups of organisms are accommodated in herbaria, where they are commonly referred to as botanical specimens.The large number of specimens in herbaria provides an ample, permanent and continuously improving knowledge base on these organisms and an indispensable source for the analysis of the distribution of species in space and time critical for current and future research relating to global biodiversity. In order to make full use of this resource, a research infrastructure has to be built that grants comprehensive and free access to the information in herbaria and botanical collections in general. This can be achieved through digitization of the botanical objects and associated data.The botanical research community can count on a long-standing tradition of collaboration among institutions and individuals. It agreed on data standards and standard services even before the advent of computerization and information networking, an example being the Index Herbariorum as a global registry of herbaria helping towards the unique identification of specimens cited in the literature.In the spirit of this collaborative history, 51 representatives from 30 institutions advocate to start the digitization of botanical collections with the overall wall-to-wall digitization of the flat objects stored in German herbaria. Germany has 70 herbaria holding almost 23 million specimens according to a national survey carried out in 2019. 87% of these specimens are not yet digitized. Experiences from other countries like France, the Netherlands, Finland, the US and Australia show that herbaria can be comprehensively and cost-efficiently digitized in a relatively short time due to established workflows and protocols for the high-throughput digitization of flat objects.Most of the herbaria are part of a university (34), fewer belong to municipal museums (10) or state museums (8), six herbaria belong to institutions also supported by federal funds such as Leibniz institutes, and four belong to non-governmental organizations. A common data infrastructure must therefore integrate different kinds of institutions.Making full use of the data gained by digitization requires the set-up of a digital infrastructure for storage, archiving, content indexing and networking as well as standardized access for the scientific use of digital objects. A standards-based portfolio of technical components has already been developed and successfully tested by the Biodiversity Informatics Community over the last two decades, comprising among others access protocols, collection databases, portals, tools for semantic enrichment and annotation, international networking, storage and archiving in accordance with international standards. This was achieved through the funding by national and international programs and initiatives, which also paved the road for the German contribution to the Global Biodiversity Information Facility (GBIF).Herbaria constitute a large part of the German botanical collections that also comprise living collections in botanical gardens and seed banks, DNA- and tissue samples, specimens preserved in fluids or on microscope slides and more. Once the herbaria are digitized, these resources can be integrated, adding to the value of the overall research infrastructure. The community has agreed on tasks that are shared between the herbaria, as the German GBIF model already successfully demonstrates.We have compiled nine scientific use cases of immediate societal relevance for an integrated infrastructure of botanical collections. They address accelerated biodiversity discovery and research, biomonitoring and conservation planning, biodiversity modelling, the generation of trait information, automated image recognition by artificial intelligence, automated pathogen detection, contextualization by interlinking objects, enabling provenance research, as well as education, outreach and citizen science.We propose to start this initiative now in order to valorize German botanical collections as a vital part of a worldwide biodiversity data pool.