1,720,973 research outputs found
Modulation of perception and brain activity by predictable trajectories of facial expressions
Get PDFPeople track facial expression dynamics with ease to accurately perceive distinct emotions. Although the superior temporal sulcus (STS) appears to possess mechanisms for perceiving changeable facial attributes such as expressions, the nature of the underlying neural computations is not known. Motivated by novel theoretical accounts, we hypothesized that visual and motor areas represent expressions as anticipated motion trajectories. Using magnetoencephalography, we show predictable transitions between fearful and neutral expressions (compared with scrambled and static presentations) heighten activity in visual cortex as quickly as 165 ms poststimulus onset and later (237 ms) engage fusiform gyrus, STS and premotor areas. Consistent with proposed models of biological motion representation, we suggest that visual areas predictively represent coherent facial trajectories. We show that such representations bias emotion perception of subsequent static faces, suggesting that facial movements elicit predictions that bias perception. Our findings reveal critical processes evoked in the perception of dynamic stimuli such as facial expressions, which can endow perception with temporal continuity
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
Functional magnetic resonance imaging data of brain area activity when recognising facial expressions
No full textData resulting from an experiment which used brain scanning or functional magnetic resonance imaging (fMRI) to investigate the brain areas active when recognising facial expressions and to learn about how they are connected and how they communicate with each other.
The dataset consists of volumetric 3D scans of brains, necessarily stored in a special, purpose-made file format. The dataset also contains information necessary for analysing the data, i.e. stimuli and their onsets times. The dataset lastly contains participant ratings of the stimuli collected in a behavioural testing session, following scanning.
Our analyses of these data are reported in papers:
(1) Furl N, Henson RN, Friston KJ, Calder AJ. 2013. Top-down control of visual responses to fear by the amygdala. J Neurosci 33:17435-43.
(2) Furl N, Henson RN, Friston KJ, Calder AJ. 2013. Network Interactions Explain Sensitivity to Dynamic Faces in the Superior Temporal Sulcus. Cereb Cortex. 2015 Sep; 25(9): 2876–2882.
Although a person's facial identity is immutable, faces are dynamic and undergo complex movements which signal critical social cues (viewpoint, eye gaze, speech movements, expressions of emotion and pain). These movements can confuse automated systems, yet humans recognise moving faces robustly.
Our objective is to discover the stimulus information, neural representations and computational mechanisms that the human brain uses when recognising social categories from moving faces. We will use human brain imaging to put an existing theory to the test. This theory proposes that recognition of changeable attributes (eg, expression) and facial identity are each recognised separately by two different brain pathways, each in a different part of the temporal lobe of the brain.
The evidence we provide might indeed support and fill in many gaps in this theory. Nevertheless, we expect instead to instantiate a new alternative theory. By this new theory, some brain areas can recognise both identities and expressions, using unified representations, with one of the two pathways specialised for representing movement. Thus, the successful completion of our project will provide a new theoretical framework sufficient to motivate improved automated visual systems and advance new directions of research on human social perception. </p
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
Face adaptation aftereffects reveal anterior medial temporal cortex role in high level category representation
Get PDFAbstractPrevious studies have shown reductions of the functional magnetic resonance imaging (fMRI) signal in response to repetition of specific visual stimuli. We examined how adaptation affects the neural responses associated with categorization behavior, using face adaptation aftereffects. Adaptation to a given facial category biases categorization towards non-adapted facial categories in response to presentation of ambiguous morphs. We explored a hypothesis, posed by recent psychophysical studies, that these adaptation-induced categorizations are mediated by activity in relatively advanced stages within the occipitotemporal visual processing stream. Replicating these studies, we find that adaptation to a facial expression heightens perception of non-adapted expressions. Using comparable behavioral methods, we also show that adaptation to a specific identity heightens perception of a second identity in morph faces. We show both expression and identity effects to be associated with heightened anterior medial temporal lobe activity, specifically when perceiving the non-adapted category. These regions, incorporating bilateral anterior ventral rhinal cortices, perirhinal cortex and left anterior hippocampus are regions previously implicated in high-level visual perception. These categorization effects were not evident in fusiform or occipital gyri, although activity in these regions was reduced to repeated faces. The findings suggest that adaptation-induced perception is mediated by activity in regions downstream to those showing reductions due to stimulus repetition
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
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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
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