1,721,022 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
Mood-dependent changes in cognitive control
No full textThe symptomatology of depression includes affective and cognitive features. As such,
depression has been associated both with maladaptive concern over emotional material, and
also with general impairments in attentional control. In the current thesis, I investigated the
potential influence of such depression-related dysfunctional emotional processing on a range
of cognitive control abilities, using experimental paradigms containing either neutral or
affective stimuli. In contrast to the hypothesis that depressive symptoms are associated with
generally compromised cognitive control, depression-related impairments were not found on
a range of ‘classic' measures of cognitive control, including error-processing (pre-error
speeding, posterror slowing and error-related ERPs), overriding response conflict (colour-word Stroop interference, conflict adaptation) or more sustained control processes (cued-RT
performance, preparatory ERPs, and maintaining long-term speed-accuracy tradeoffs).
Interestingly, however, differences between groups with low and elevated levels of depressive
symptoms emerged during the performance of emotionally valenced tasks. First, an elevated
depressive symptom group showed a reduced ability to resolve emotional conflict arising
between competing affective representations. When compared with spared performance on
the classic Stroop task, this result suggests that depressive symptoms are associated with a
specific impairment in the ability to regulate emotional distraction. Secondly, an ERP related
to advanced preparation in cued-RT tasks (the CNV), but not those associated with early
perceptual processing (P1, N170), was selectively modulated by negative, but not positive,
task-irrelevant emotional distractors presented during the cue-target interval. This pattern of
ERP results supports a late processing locus of affective attentional bias in depression.
Together, the current results propose that control processes which facilitate the regulation of
emotional material (i.e. over emotional sources of distraction) might be selectively affected
by increased depressive symptoms, suggesting that future work should consider affective
variables when investigating executive control processes in depression
The effects of conflict strength and ageing on cognitive control
Get PDFElectronic redacted version excludes material for which permission has not been granted by the rights holderIn this thesis, I investigated effects of conflict strength and ageing on cognitive control. Conflict strength was manipulated in the Eriksen flanker task using two different approaches: 1. independent variation of flanker and target contrast; 2. manipulation of stimulus onset asynchrony (SOA). Reducing flanker contrast relative to target contrast decreased conflict strength, as shown by a reduction in compatibility effects, when contrast conditions were presented in a randomized fashion but not when they were presented block-wise. An SOA of 100 ms did lead to increased compatibility effects compared to SOAs of 0 ms and 200 ms. Effects of conflict appear to be reflected in the N2 component of the ERP. Although priming played a crucial role in the emergence of the sequential adjustment effect, conflict strength also influenced this effect to a certain degree, supporting the claim that sequential adjustments represent an adaptation of cognitive control. Post-error slowing and error-related ERP components, on the other hand, were not affected by the conflict manipulations, suggesting that errors cannot be explained in terms of conflict processing. Effects of ageing on cognitive control were investigated in a group of middle-aged participants. Although physiological indicators of conflict and error processing were compromised in this age group and overall response times were increased, compatibility, sequential adjustment, and post-error slowing effects were of comparable size as in young adults. These findings suggest that participants could successfully compensate for age-related physiological changes at this early stage of ageing. In conclusion, the research presented in this thesis provided important information to extend our knowledge of factors influencing cognitive control processes
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
Investigating the link between intrusive memories and cognitive control
Get PDFIntrusive memories are memories for negative autobiographical events that come to
mind without being deliberately recalled (Hackmann, Ehlers, Speckens, & Clark,
2004). Previous research has demonstrated that intrusive memories, and negative
reactions to intrusive memories, are an important feature of depression (Starr &
Moulds, 2006; Williams & Moulds, 2008b) and contribute to the maintenance of
depression longitudinally (Newby & Moulds, 2011c). It has also been established that
intrusive memory experience is related to individual differences in cognitive control,
specifically in proactive interference resolution (Verwoerd, Wessel, & de Jong, 2009;
Verwoerd, Wessel, de Jong, Nieuwenhuis, & Huntjens, 2011). The present thesis
aimed to extend upon these existing findings, using the Dual Mechanism of Control
theory, which distinguishes between proactive and reactive modes of control (Braver,
Gray, & Burgess, 2007). Furthermore, in view of some recent ambiguity of the
defining feature of an intrusive memory, as compared to a negative involuntary
memory more generally (Kvavilashvili, 2014; Moulds & Krans, 2015), another goal
of the thesis was to incorporate a wider focus of involuntary memories, rather than
focusing only on traditionally studied intrusive memories. Participants from the
student population and local community were tested. Overall, results provide some
evidence for a negative involuntary memory related deficit in proactive control, on
both a classic and an emotional version of the AX-Continuous Performance Task
(AX-CPT). Conversely, there was no link between intrusive or involuntary memory
experience and reactive control. A brief mindfulness and self-compassion based
intervention, designed to reduce negative reactions to intrusive memories, was also
tested. The intervention was successful in reducing intrusive-memory distress, and
recommendations for the future development of the intervention are presented
Effectiveness of seller reputation as a solution to online lemon markets
No full textLemon markets, markets of asymmetric information in favour of sellers, cause selective market participation and exploitation of market conditions, known as adverse selection and moral hazard. To prevent both in online lemon markets that emerged with the Sharing Economy, connecting fragmented individuals to share, exchange, or sell underutilised assets, seller reputation mechanisms have been installed to signal trust.
Their impact is corroborated by the reputation effect: commercial outcome increases with seller reputation. However, the underlying assumption of rational market participants, small, heterogeneous effect sizes, and few, unclear findings on marketplace design- and product-related moderation of the reputation effect question: Is seller reputation an effective solution to the problems associated with online lemon markets?
In a twofold approach, seller reputation is studied through an observational study analysing eBay data and experimental studies using consumer behaviour in virtual marketplaces – to better understand the reputation effect, commercial effects of marketplace design and product attributes, and their moderation of the reputation effect.
On eBay, the reputation effect holds with substantial commercial impact, despite limited seller distinction given ceiling effects in reputation system design. Sniping, incentivised by marketplace design generally reduces commercial outcome. Product attributes, sealed packaging and private photos, increase commercial outcome, and reduce the reputation effect. The reputation effect is experimentally confirmed and its product-related moderation supported. On eBay, photo frequency increases commercial outcome across seller cues and prior photo exposure is experimentally linked to it, partly via trust – in line with mere exposure, a preference for familiar stimuli.
Findings suggest that seller reputation systems, though constrained by design deficiencies, effectively address problems associated with online lemon markets. While product attributes appear to complement seller reputation as trust-building signalling mechanisms, prior exposure to them may constitute an independent mechanism; jointly contributing to explain differences in observed commercial outcome
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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