1,721,030 research outputs found
Cognitive load in switching between egocentric and allocentric spatial frames of reference: a pupillometry study
No full textEvery day we combine and switch between body-centered (egocentric) and object-centered (allocentric) spatial representations. Several studies so far have reported a greater difficulty to switch from an allocentric reference frame to an egocentric one than vice-versa. To clarify this effect, the present work measured the cognitive load underlying switching vs. non-switching processes between reference frames through cognitive pupillometry. Participants performed a custom-designed visuo-spatial memory task, while pupil dilation variations were measured with eye-tracking. After memorizing triads of objects, participants provided judgments of relative distance in non-switching (only-egocentric, only-allocentric) and switching (from-ego-to-allo, from-allo-to-ego) conditions. The results showed a larger pupil dilation in switching judgments from-allocentric-to-egocentric reference frames than from-egocentric-to-allocentric ones. Moreover, pupil evoked-responses were also larger in allocentric- than egocentric-based non-switching conditions. Overall, the results showed that, for both non-switching and switching visuo-spatial processes, starting from an allocentric-based representation elicits a higher cognitive load than starting from an egocentric-based one. Thus, the disproportional effort in visuo-spatial switching processes seems to be determined by the first reference frame adopted that, in turn, contaminates also the following one
Allocentric coordinate spatial representations are impaired in aMCI and Alzheimer’s Disease Patients
No full textResearch has reported deficits in egocentric (subject-to-object) and mainly allocentric (object-to-object) spatial representations in the early stages of the Alzheimer’s disease (eAD). To identify early cognitive signs of neurodegenerative conversion, several studies have shown alterations in both reference frames, especially the allocentric ones in amnestic-Mild Cognitive Impairment (aMCI) and eAD patients. However, egocentric and allocentric spatial frames of reference are intrinsically connected with coordinate (metric/variant) and categorical (non-metric/invariant) spatial relations. This raises the question of whether allocentric deficit found to detect the conversion from aMCI to dementia is differently affected when combined with categorical or coordinate spatial relations. Here, we compared eAD and aMCI patients to Normal Controls (NC) on the Ego-Allo/Cat-Coor spatial memory task. Participants memorized triad of objects and then were asked to provide right/left (i.e. categorical) and distance based (i.e. coordinate) judgments according to an egocentric or allocentric reference frame. Results showed a selective deficit of coordinate, but not categorical, allocentric judgments in both aMCI and eAD patients as compared to NC group. These results suggest that a sign of the departure from normal/healthy aging towards the AD may be traced in elderly people’s inability to represent and compared distances among elements in the space
Congenital blindness limits allocentric to egocentric switching ability
No full textMany everyday spatial activities require the cooperation or switching between egocentric (subject-to-object) and allocentric (object-to-object) spatial representations. The literature on blind people has reported that the lack of vision (congenital blindness) may limit the capacity to represent allocentric spatial information. However, research has mainly focused on the selective involvement of egocentric or allocentric representations, not the switching between them. Here we investigated the effect of visual deprivation on the ability to switch between spatial frames of reference. To this aim, congenitally blind (long-term visual deprivation), blindfolded sighted (temporary visual deprivation) and sighted (full visual availability) participants were compared on the EgoâAllo switching task. This task assessed the capacity to verbally judge the relative distances between memorized stimuli in switching (from egocentric-to-allocentric: EgoâAllo; from allocentric-to-egocentric: AlloâEgo) and non-switching (only-egocentric: EgoâEgo; only-allocentric: AlloâAllo) conditions. Results showed a difficulty in congenitally blind participants when switching from allocentric to egocentric representations, not when the first anchor point was egocentric. In line with previous results, a deficit in processing allocentric representations in non-switching conditions also emerged. These findings suggest that the allocentric deficit in congenital blindness may determine a difficulty in simultaneously maintaining and combining different spatial representations. This deficit alters the capacity to switch between reference frames specifically when the first anchor point is external and not body-centered
Feeling Across the Distance: The Interplay of Motor and Empathic Processes with Virtual Humans
No full textImmersive technologies enable increasingly frequent and complex interactions with "Virtual Humans" (VHs), now endowed with anthropomorphic behaviour and appearance. Therefore, it is important to explore the psychological mechanisms underlying social interaction between people and VHs. To this end, we investigated whether motor simulation mechanisms influence localization of stimuli at near (peripersonal) or far (extrapersonal) distances from a VH and whether empathic traits correlate with the task. In an immersive virtual reality environment, participants had to determine the position (right/left) of an object relative to VHs who could have their arms blocked (motor interference) or free (full motor availability) and could appear near or far from participants. Furthermore, we assessed the participants’ empathic traits using the Interpersonal Reactivity Index (IRI). We hypothesized that motor interference should slow down the localization of objects in peripersonal space, i.e., a space of action and defence. An association between empathic traits and spatial performance was expected, especially in extrapersonal space. The results confirmed these hypotheses, showing a deep engagement with the VHs based on motor simulation in peripersonal space and associated to the empathic tendency to identify with a fictitious character in extrapersonal space
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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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