1,720,987 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Simplicity in perceptual organization
No full textA long-standing debate in perception concerns the question of whether perceptual organization is guided by internal efficiency (the simplicity principle) or by external veridicality (the likelihood principle). This article focuses on the simplicity principle which is a modern information-theoretic version of Occam’s razor, but also compares it to the likelihood principle which reflects classical information theory. Both principles can be modelled by Bayes’ rule which combines quantifications of view-independent and view-dependent factors to predict stimulus interpretations. Whereas the likelihood principle relies on hardly quantifiable frequencies of occurrence of things in the world, the simplicity principle relies on better quantifiable structural complexities of individual things. The simplicity principle is further argued to be sufficiently veridical in everyday perception, and neurally realizable via cognitive architecture enabling transparallel processing. This quantum-like form of representational processing relates to connectionist modelling and complements dynamic-systems ideas about neuronal synchronization.edition: 1ststatus: Publishe
Human visual perceptual organization beats thinking on speed
No full textWhat is the degree to which knowledge influences visual perceptual processes? This question, which is central to the seeing versus thinking debate in cognitive science, is often discussed using examples claimed to be proof of one stance or another. It has, however, also been muddled by the usage of different and unclear definitions of perception. Here, for the well-defined process of perceptual organization, I argue that including speed (or efficiency) into the equation opens a new perspective on the limits of top-down influences of thinking on seeing. While the input of the perceptual organization process may be modifiable and its output enrichable, the process itself seems so fast (or efficient) that thinking hardly has time to intrude and is effective mostly after the fact.sponsorship: I thank Dan Coates, Sander van de Cruys, and Vebjorn Ekroll for their inspiring discussion session, in Vielsalm, on seeing versus thinking. This research was supported by Methusalem grant METH/14/02 awarded to Johan Wagemans (www.gestaltrevision.be). (Methusalem grant|METH/14/02)status: Publishe
Simplicity versus likelihood in visual perception: From surprisals to precisals
No full textThe likelihood principle states that the visual system prefers the most likely interpretation of a stimulus, whereas the simplicity principle states that it prefers the most simple interpretation. This study investigates how close these seemingly very different principles are by combining findings from classical, algorithmic, and structural information theory. It is argued that, in visual perception, the two principles are perhaps very different with respect to the viewpoint-independent aspects of perception but probably very close with respect to the viewpoint-dependent aspects which, moreover, seem decisive in everyday perception. This implies that either principle may have guided the evolution of visual systems and that the simplicity paradigm may provide perception models with the necessary quantitative specifications of the often plausible but also intuitive ideas provided by the likelihood paradigm.status: Publishe
The dynamics of Prägnanz
No full textThere is quite wide-spread agreement about the relevance of pattern Prägnanz (Koffka, 1935) with respect to the human interpretation of visual patterns. There is less agreement about whether pattern Prägnanz is based solely on pattern information (static) or also on the history of the perceiver (dynamic). In Van Leeuwen and Van den Hof (1991), experimental data concerning serial patterns are presented within the framework of the dynamic-network approach initiated by Buffart (1986, 1987). These experimental data are claimed to give evidence against the static-coding approach initiated by Leeuwenberg (1969, 1971). In the present paper, however, I show first that Buffart's theoretical basis is incorrect, and that in fact Leeuwenberg's static-coding approach is the basis for the dynamic-network approach. Second, I show that those experimental data rather give evidence in favor of the static-coding approach, by using those same data for a test of the most recent static-coding model (Van der Helm & Leeuwenberg, 1991; Van der Helm, Van Lier, & Leeuwenberg, 1992). Finally, I propose a reconciliation between the two approaches, in the sense that the dynamic-network model could be shaped in such a way that it yields a simulation, and maybe even an enrichment, of the static-coding model.status: Publishe
Structural coding versus free-energy predictive coding
No full textFocusing on visual perceptual organization, this article contrasts the free-energy (FE) version of predictive coding (a recent Bayesian approach) to structural coding (a long-standing representational approach). Both use free-energy minimization as metaphor for processing in the brain, but their formal elaborations of this metaphor are fundamentally different. FE predictive coding formalizes it by minimization of prediction errors, whereas structural coding formalizes it by minimization of the descriptive complexity of predictions. Here, both sides are evaluated. A conclusion regarding competence is that FE predictive coding uses a powerful modeling technique, but that structural coding has more explanatory power. A conclusion regarding performance is that FE predictive coding-though more detailed in its account of neurophysiological data-provides a less compelling cognitive architecture than that of structural coding, which, for instance, supplies formal support for the computationally powerful role it attributes to neuronal synchronization.status: Publishe
A cognitive architecture account of the visual local advantage phenomenon in autism spectrum disorders
No full textIdeally, a cognitive architecture is a neurally plausible model that unifies mental representations and cognitive processes. Here, I apply such a model to re-evaluate the local advantage phenomenon in autism spectrum disorders (ASD), that is, the better than typical performance on visual tasks in which local stimulus features are to be discerned. The model takes (a) perceptual organization as a predominantly stimulus-driven process yielding hierarchical stimulus organizations, and (b) attention as predominantly scrutinizing the hierarchical structure of established percepts in a task-driven top-down fashion. This accounts for a dominance of wholes over parts and implies that perceived global structures mask incompatible local features. The model also substantiates that impairments in neuronal synchronization - as found in ASD - reduce the emergence of global structures and, thereby, their masking effect on incompatible features. I argue that this explains the local advantage phenomenon and I discuss implications and suggestions for future research.sponsorship: I thank Arpad Csatho, Emanuel Leeuwenberg, Bilge Sayim, Sander Van de Cruys, Ruth Van der Hallen, Gert van der Vloed, and Johan Wagemans for valuable discussions on various aspects of this study. This research was supported by Methusalem grant METH/08/02 awarded to Johan Wagemans (www.gestaltrevision.be). (Methusalem grant|METH/08/02)status: Publishe
Symmetry perception
No full textDetection of (mirror) symmetry—which is abundantly present in the world—is often assumed to be an integral part of the perceptual organization process that is applied to every visual stimulus. On the one hand, as reviewed in this article, the exact role of symmetry in perceptual organization is actually rather elusive due to its interaction with other grouping factors. On the other hand, the detectability of single and multiple symmetry is indeed extraordinary in comparison to that of repetition and Glass patterns. Empirical and theoretical findings pertaining to this detectability are discussed, focusing on converging evidence rather than on details of individual studies, and putting various findings in evolutionary perspectives. Reflecting a seeming opposition between process models and representation models, a specific question is whether symmetry detection relies on crude or precise correspondences between symmetry halves. Both stances find psychophysical support, and this article ends with a unification proposal.edition: 1ststatus: Publishe
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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