1,721,010 research outputs found
The Pot/Lid illusion in parallel perspective
No full textOne of us has frequently chosen a pot lid that was too big. Hypothesizing the error was a problem with foreshortening, we depicted a cylinder in parallel perspective, tilted 30°, with the top circle foreshortened to a 2D ellipse. Parallel projection provides foreshortening without convergence. Observers judged which of two 2D ellipses was identical to the one depicting the cylinder’s top. One had the same dimensions as the ellipse depicting the cylinder top, 40 mm wide and 15 mm tall, and the other one was bigger, 41 x 18. The observers chose the bigger ellipse.
An ellipse depicting a cylinder’s top may look bigger because of crosstalk from perceptual information for a circle in perspective. This information for a tilted 3D surface “biases” perception -- merely biasing the 2D ellipse towards the circle. The 2D ellipse’s apparent eccentricity is simply lessened -- it does not go all the way to a perfect circle. With respect to our original errors with real pot lids, if depicting ellipses can be biased towards circles then surely really circular pot lids can be similarly biased towards ellipses, when the lids are viewed highly tilted
L’illusione Pentola/coperchio
No full textIntroduzione
Il nome, illusione pentola/coperchio, è dovuto al fatto che, spesso, quando si sceglie un coperchio per una pentola (tra diversi coperchi di dimensioni differenti in un cassetto) si prende erroneamente quello più grande. Per verificare questo errore abbiamo condotto diversi esperimenti con cilindri ed ellissi di diverse dimensioni e con una pentola e coperchi reali.
Metodo
Presentiamo la versione finale dell’illusione che consiste in un cilindro opaco (30 mm di altezza x 40 mm di larghezza) rappresentato in prospettiva parallela, inclinato di 30°. La proiezione prospettica del cerchio superiore del cilindro risulta un’ellisse di 15 mm di H x 40 mm di L. Il compito di 60 partecipanti era quello di confrontare due ellissi (la prima uguale e la seconda più grande, 18 mm H x 41 mm L) con l’ellisse/cerchio del cilindro.
Nel secondo esperimento abbiamo preso in considerazione una pentola vera e propria (20 cm di altezza x 15 cm di diametro) con 5 coperchi di dimensioni diverse presentati con un’inclinazione di circa 30°. Il compito di 120 partecipanti era quello di scegliere il coperchio che avesse lo stesso diametro della pentola.
Risultati
I risultati mostrano che solo 9 (15%) su 60 partecipanti hanno scelto l’ellisse corretta (p<.001), e solo 27 (22,5%) su 120 partecipanti hanno scelto il coperchio corretto, tutti gli altri hanno scelto i coperchi più grandi (p<.001).
Conclusioni
I risultati ottenuti in entrambi gli esperimenti dimostrano la veridicità dell’illusione. L’ellisse raffigurante la parte superiore di un cilindro potrebbe sembrare più grande a causa di un’interferenza che proviene dalle informazioni percettive di un cerchio in prospettiva. I partecipanti aumentano la dimensione dello stimolo di confronto perché in questo modo diminuiscono l’eccentricità e aumentano l’area di superficie. Inoltre, nel caso dei coperchi, la visione di scorcio potrebbe portare a valutazioni errate dei coperchi circolari reali
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
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