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Hvernig skynjum við hópa ólíkra áreita?
No full textIn daily life, people often see groups of similar objects compressed into a single percept. For instance, many people standing together form a crowd, and individual cars moving along the road form traffic. The general impression of traffic speed or crowd mood is perceived without paying much attention to each individual object. Nevertheless, this general impression accurately approximates the whole group. Numerous studies have shown that the visual system can rapidly and accurately represent summary statistics of multiple objects (so-called ensembles) despite observers’ poor ability to recall individual items upon which the ensemble representation was built. These findings raise many questions regarding the mechanisms that encode summary statistics, particularly concerning the contribution of individual items to the ensemble representation. Is the ensemble representation built upon the entire group of items or just a subsample? Do sampled items have equal weight in the encoded summary statistics, or do some items determine the ensemble perception while the rest have a minor impact? These questions are addressed in the three papers of this thesis.
In the first paper, we employed computational modeling and behavioral experiments to investigate sampling and robust averaging, which implies larger weight for central elements and lower weight for statistical outliers. Observers adjusted the mean orientation of ensembles with skewed orientation distributions. In line with previous studies, our observers estimated the mean with a systematic bias away from the ensemble mean toward its mode. The bias magnitude increased with the ensemble distribution skewness. This bias can be interpreted in terms of robust averaging: greater skewness means that the extreme elements of the skewed part of the distribution become more deviant from the mean. The more deviant they are, the less their contribution is. As a result, the perceived mean shifts away from the skewed part of the ensemble distribution toward its mode. This pattern was well predicted by the population coding model that utilizes neuron population coding and pooling mechanisms. We conclude, therefore, that this model can be considered a neurally plausible implementation for exhaustive item sampling and robust averaging in ensemble perception.
In the second and third papers, we investigated the effect of saliency on item contribution to ensemble representation (so-called amplification effect) using explicit and implicit reports. Specifically, we tested whether less salient items contribute at all. Our observers performed a mean orientation adjustment task (explicit report) and a visual search for an odd-oriented line among heterogeneous distractors (implicit report). We varied item saliency via size and measured the accuracy and precision of mean orientation estimation in the explicit report and search time in the implicit report. Using explicit reports, we found a strong orientation estimation bias toward the orientation of the more salient items. Still, the observed bias was smaller than what would be produced by subsampling and averaging the most salient items alone. Moreover, less salient items affected the precision of the reported mean. We conclude, therefore, that saliency modulates item contribution to the ensemble representation but does not absolutely determine item sampling. Conversely, we observed no effect of saliency on implicitly reported statistics, suggesting that explicit and implicit ensemble representations may be implemented by different mechanisms.Í daglegu lífi sjá fólk oft hópa af svipuðum hlutum samþjappaða í heildarskynjun. Til
dæmis mynda mörg einstök áreiti sem mynda hópa, og margir einstakir bílar á ferð eftir
veginum mynda umferð. Almenna tilfinningin fyrir umferðarhraða eða stemningu
mannfjöldans er skynjuð án þess að mikið sé einblínt á hvern einstakan hlut. Þessi
almenna skynjun gefur fremur nákvæma áætlun um einkenni hópsins í heild. Fjöldi
rannsókna hefur sýnt að sjónkerfið getur hratt og nákvæmlega áætlað samantektartölur
margra hluta (svokölluð áreitasöfn), þrátt fyrir að áhorfendum gangi illa að muna eftir
einstökum hlutum sem mynda þessa hópa. Þessar niðurstöður vekja spurningar um þau
ferli sem kóða samantektartölur, sérstaklega hvað varðar framlag einstakra hluta til
skynjunar á áreitasafninu. Byggir safnið á öllum hlutum hópsins eða aðeins á litlu úrtaki
þeirra? Hafa allir hlutir hópsins jafna mikla vigt eða stjórna sumir hlutir skynjun
áreitsafnsins á meðan aðrir hafa minni áhrif? Þessum spurningum er svarað í þremur
greinum þessarar ritgerðar.
Í fyrstu grein notum við líkön og tilraunir til að sýna að hlutir nálægt miðju safnsins hafa
meiri áhrif en tölfræðilegir útlagar. Í samræmi við fyrri rannsóknir áætluðu áhorfendur
okkar meðaltalið með kerfisbundnu fráviki frá meðaltali samansafnsins í átt að algengasta
gildi þess. Frávikið jókst með aukinni skekkju í dreifingu áreitasafnsins. Meiri skekkja
þýðir að öfgahlutir skekkta hluta dreifingarinnar verða meira frábrugðnir meðaltalinu. Því
meira frábrugðnir sem þeir eru, því minna leggja þeir til. Afleiðingin er að skynjaða
meðaltalið færist frá skekkta hlutanum í dreifingu samansafnsins í átt að tíðasta gildinu.
Líkan sem bygggir á kóðun heildarsafna áreita og samvinnu taugafrumna spáði vel fyrir
um þetta.
Í annarri og þriðju grein rannsökuðum við áhrif áberandi áreita á skynjun áreitasafna
(svokölluð mögnunaráhrif). Við prófuðum hvort minna áberandi hlutir legðu eitthvað til
skynjunar áreitasafnanna. Þátttakendur framkvæmdu verkefni þar sem þeir stilltu
meðaltalsstefnu og leituðu eftir frábrugðinni stefnu meðal sundurleitra truflunaráreita. Við
breyttum áberandi hluta með stærð og mældum nákvæmni stefnumats og leitartíma. Við
fundum sterkt frávik í stefnumati í átt að stefnu áberandi hluta þegar þátttakendur svöruðu
beint. Enn fremur var frávikið minna en það sem hefði myndast við úrtak og meðaltal
áberandi hluta eingöngu. Að auki höfðu minna áberandi hlutir áhrif á nákvæmni skráðrar
meðaltalsstefnu. Við ályktum því að áberandi áreiti í áreitasöfnum stýri framlagi hluta til
samansafnsskynjunar, en ákveði ekki algerlega þessi áhrif. Aftur á móti fundum við lítil
áhrif óbeinnar skynjanar á skynjun áreitasafnanna, sem bendir til þess að skýr og óbein
samansafnsskynjun gæti verið útfærð með mismunandi hætti og ólíkum ferlum.This work was supported by grant #228366 from the Icelandic Research Fund and the research fund of the University of Icelan
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
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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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