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Do your actions help me remember better? Effects of pointing movements performed by self and others on visuo-spatial working memory: evidence from behavioral, eye-tracking and event-related potential data
Full text linkThe current dissertation investigates how pointing movements performed towards to-be-
remembered target locations together with a task-partner influence visuo-spatial working
memory (VSWM). Previous studies have shown that, under specific conditions, spatial arrays that have been pointed to during encoding are better recognized than passively viewed ones. The first experiment described here was aimed at replicating these results. Participants were presented with two spatial arrays, one of which was encoded through mere visual observation (the no-move array), while the other was encoded through observation accompanied by pointing movements towards target locations (the move array). The encoding was followed by a recognition test in which participants had to decide whether a probe array was equal or different from one of the arrays presented during the study phase. Results replicated the memory advantage of pointed-to arrays as compared to merely observed ones. Since a number of studies suggest that perceiving an action and executing it are functionally equivalent and activate common representational structures, we proceeded to investigate whether pointing movements performed by a task-partner could have similar effects. No memory advantage was found when participants passively observed the pointing movements performed by the task-partner. A joint condition of the task was thus tested where the participant and the task-partner took turns in performing the pointing movements towards the target locations in the move array (recognition
was always performed by the participants). Results showed that in this joint-action condition the pointing movements performed by the task-partner benefited individual’s visuo-spatial working memory to the same extent as self-performed pointing movements. Further experiments were conducted to investigate the processes underlying the encoding of no-move and move arrays, either jointly pointed by the participant and the task-partner or pointed only by the task-partner. In two eye-tracking experiments, the eye movement patterns for the two types of arrays were recorded. The analysis of eye movements yielded results that are in line with the behavioral findings and showed that fixations to move arrays were higher in number and longer in duration than the fixations to no-move arrays but only when the participant and the task-partner alternate in making the pointing movements. No difference in eye movement patterns was found for the move and no-move arrays when the participant merely observed pointing movements performed by the task-partner. We propose that, in the joint-action condition, self and others’ actions are
coded at the same representational level and their functional equivalency is reflected in a similar pattern of eye fixations. Behavioral experiments investigating the effects of a number of other factors on visuo-spatial working memory are also reported, including the partner’s involvement in the task or the animacy of the task-partner. Findings show that: a) in the joint-action condition, the infrequent execution of pointing movements by the participants (about 16%) is sufficient to successfully produce a social context which leads to the co-representation of partner’s actions; and b) a memory advantage occurs when the turn-taking task-partner is replaced by a moving cartoon hand, but only in the joint-action condition (there is no advantage when the movements were only carried out by the cartoon hand). The latter finding indicates that the mere presence of the cartoon hand is not sufficient to trigger the memory advantage. Altogether, the results suggest that the social context between the participant and the task-partner modulates the task co-representation process. Finally, event related potential (ERP) data were recorded in order to investigate the encoding processes involved in processing self and other’s pointing movements in
the joint-action condition. In summary, the current dissertation investigates, from behavioral and physiological points of view, the question of how performing an action together with a partner influences individual’s encoding processes and suggests future directions for research investigating the influence of jointly performed tasks on individual’s memory
You and the hand: investigating the effects of other-performed pointing movements on visuo-spatial memory
No full textPrevious studies have shown that self-performed pointing movements at encoding facilitate performance in a visuo-spatial recognition task. In the present study we investigated whether other-performed movements can produce similar effects and if the effect is limited to a human co-actor. Participants observed and were instructed to remember two consecutive arrays of three or four items, one encoded only by visual observation, the other by visual observation accompanied by pointing movements. In three experiments, pointing movements were performed either solely by the experimenter (Exp. 1), or by the participant alternating with the experimenter (Exp. 2) or with an animated hand (Exp. 3). We found that pointing movements performed by the experimenter facilitated array recognition only when they were alternated with self-performed movements. The same results hold when the human co-actor was replaced by an animated hand in Exp. 3. The results suggest that observing others performing the movement leads to active motor simulation only when it is associated to the self- execution of the same movement
Task irrelevant external cues can influence language selection in voluntary object naming: evidence from Hindi-English bilinguals
Full text linkWe examined if external cues such as other agents’ actions can influence the choice of language
during voluntary and cued object naming in bilinguals in three experiments. Hindi–
English bilinguals first saw a cartoon waving at a color patch. They were then asked to either
name a picture in the language of their choice (voluntary block) or to name in the instructed
language (cued block). The colors waved at by the cartoon were also the colors used as language
cues (Hindi or English). We compared the influence of the cartoon’s choice of color
on naming when speakers had to indicate their choice explicitly before naming (Experiment
1) as opposed to when they named directly on seeing the pictures (Experiment 2 and 3).
Results showed that participants chose the language indicated by the cartoon greater number
of times (Experiment 1 and 3). Speakers also switched significantly to the language
primed by the cartoon greater number of times (Experiment 1 and 2). These results suggest
that choices leading to voluntary action, as in the case of object naming can be influenced
significantly by external non-linguistic cues. Importantly, these symbolic influences can work
even when other agents are merely indicating their choices and are not interlocutors in bilingual
communicatio
Synthesis of Al and Ag nanoparticles through ultra-sonic dissociation of thermal evaporation deposited thin films for promising clinical applications as polymer nanocomposite
Full text linkNanoparticles (NPs) having well-defined shape, size and clean surface serve as ideal model system to investigate surface/interfacial reactions. Ag and Al NPs are receiving great interest due to their wide applications in bio-medical field, aerospace and space technology as combustible additives in propellants and hydrogen generation. Hence, in this study, we have synthesized Ag and Al NPs using an innovative approach of ultra-sonic dissociation of thin films. Phase and particle size distributions of the Ag and Al NPs have been determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thin film dissociation/dissolution mechanism, hence conversion into NPs has been characterized by SEM- scanning electron microscope. EDXA & ICPMS have been performed for chemical analysis of NPs. Optical properties have been characterized by UV-Vis and PL spectroscopy. These NPs have also been investigated for their anti-bacterial activity against Escherichia coli bacteria. To the best of our knowledge, this is the first time when NPs has been synthesized by ultra-sonic dissociation of thin films. As an application, these NPs were used further for synthesis of nanocomposite polymer membranes, which show excellent activity against bio film formation
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
Is it necessary to measure all brain regions for the assessment of PAF?
Full text linkFrom decades of research, electroencephalography (EEG) has been proved as a potential non-invasive medical
technique to measure the electrophysiological activities of brain. Alpha is one of the most prominent frequency
bands of EEG because of its applications in cognitive enhancement and biofeedback methods. 300 participants
were included in the present study to investigate the relationships between their cognitive performance and Peak
Alpha Frequency (PAF). Brain activity was recorded from all significant brain regions in 250 participants and
only from occipital region in 50 participants. The aim of the present study was to ensure the brain region which
is the most dominant one to measure PAF/ IAF. Power Spectrum Density (PSD) method was used for EEG
signal analysis. Interrelationship among PAF, IAF and PAF of six individual electrode positions was also
explored. Findings reveled that parieto- occipital electrode points are sufficient to assess one’s peak alpha
frequency
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