Spelling suggestions: "subject:"isi"" "subject:"aisi""
171 |
Choice-supportive misremembering: A robust phenomenon?Lind, Martina January 2019 (has links)
Although the literature on choice-supportive memory – remembering the items of chosen options as more preferential and those of non-chosen options as less preferential than they actually were – is scarce and scattered, it has widely been accepted as a solid phenomenon that could lead to biased future decisions. In the published studies to date, different types of such misremembering have been observed using rather dissimilar methods, with the large majority testing memory solely with source recognition. The characteristics of the material to be remembered have not been particularly varied and the effect of different delay levels has not been properly investigated. Thus, at the onset of this project, there was a lack of insight into the nature and robustness of the phenomenon and no systematic review of the relevant literature had been done to provide an integrative assessment of its status. The objectives and scope of the current project are the following: (1) to conduct a systematic literature review on the phenomenon of choice-supportive misremembering; (2) to propose a new comprehensive taxonomy of the different types of memory distortions after choice, and (3) to investigate the empirical support for the proposed taxonomy and explore the conditions necessary for the choice-supportive misremembering effect. The first experiment involved four choice scenarios and had a typical design for studies in the decision-making literature (information presented in tables with a low number of attributes and only the value of each one differing between the two options). Memory was tested with free and cued recall only, and the delay between the choice and the memory tests was manipulated on three levels (2 minutes, 20 minutes, and 2 days). The results fully supported the proposed taxonomy, but also highlighted the absence of choice-supportive misremembering despite the high statistical power of the tests. In the second experiment, the scenarios and options were more complex and verbose, with a higher number of items. Four different scenarios were used and presented in two different formats (‘narrative’ vs list) as well as in an alignable and an unalignable version. The narrative versions presented the items of the two options in blocks of text (Option A above Option B), whereas the list versions displayed each item on a separate line (Option A adjacent to Option B). In the alignable version, the items presented had corresponding items on the same dimension in both options, while there was no such correspondence in the unalignable version. This time, memory was tested with free and cued recall in addition to a source recognition test that has hitherto been more typical for studies on choice-supportive misremembering. In common with the first study, this second experiment provided full support for the proposed taxonomy, but it also demonstrated the existence of the choice-supportive misremembering effect regardless of the manipulated variables. Considered in unity, the results of the two experiments suggest that the type of stimuli used is a decisive factor and confirm that the phenomenon does not occur with the kind of materials typically used in the decision-making literature. Indeed, when participants are more likely to compare the options item by item rather than rely on gist-based processing, they do not seem to exhibit choice-supportive memory effects. This observation and the findings from the literature review and the two experiments are discussed in light of the various theories that have been proposed to explain misremembering. Finally, suggestions on how to further expand the knowledge through new research studies on specific populations are put forward.
|
172 |
Cognition of Parenting: The effect of biological factors and cognitive processes and their interaction on adult responsiveness to baby signalsRigo, Paola January 2013 (has links)
In the last decade, neurobiological studies have focused efforts on investigating the biological substrates (i.e., cerebral structures, neurotransmitters, and hormones) underlying parental attuned behavior to salient infant stimuli (i.e., infant cries), that plays an important role in child affective, social, and cognitive development (Venuti, 2007; Bornstein, 2002). Both human and animal studies have primarily focused on the neurobiology of mothers and have shown that subcortical and cortical cerebral structures such as the prefrontal cortex, thalamocingulate network, hypothalamus, amygdala, and substantia nigra are important in maternal motivation and attuned behaviors (Barrett & Fleming, 2010; Swain, Lorberbaum, Kose, & Strathearn,2007). However, there is a lack of literature concerning gender differences and only a few studies have investigated the sensitivity of response to infant stimuli in non-parent adults (Caria, de Falco, Venuti, Lee, Esposito, Rigo, Birbaumer & Bornstein, 2012; Glocker, Langleben, Ruparel, Loughead, Gur & Sachser, 2009; Parsons, Young, Kumari, Stein & Kringelbach, 2011; Montoya, Landi, Kober, Worhunsky, Rutherford, Mencl, Mayes & Potenza, 2012).
In this research project we focused our investigations on mechanisms in human adults (parents and non-parents) involved in parental care, and in specific: (a) on neural mechanisms underlie BOLD response to infant vocalizations, crying in particular; (b) on brain changes (grey matter volume) occurring during the early postpartum period in new fathers.
Using functional magnetic resonance imaging (fMRI), in the first study (second chapter) we looked at gender differences in resting-state brain activation associated with the cry condition at the default mode network (DMN) level in a sample of healthy adults (parents and nonparents). The design was balanced by parental status and gender. The DMN is preferentially activated when individuals are not involved in externally oriented tasks, namely during the mind wandering and it is deactivated during external goal-oriented activities.
In the second longitudinal study (third chapter) we investigated in new fathers the GM volumes change amongst 2-4 weeks and 3-4 months postpartum in brain areas responsible for parental behaviors over time during the early postpartum period. Anatomical changes and their relationships with parenting behaviors have never been examined in human fathers despite the importance of paternal care for child development.
In the third study (fourth chapter) we investigated, using fMRI and behavioral (Response Time RT) techniques, how the pattern of cerebral activation when listening to infant cry modulates concomitant behavioral tasks, which could require or not require the attention toward the cry stimuli, and thus affecting parental responsiveness.
|
173 |
Hemispheric Specialization Tied to Lateralized Motor Preference in Human and Non-Human PrimatesQuaresmini, Caterina January 2011 (has links)
In literature there are large discrepancies about methods to assess cerebral lateralization in both human and nonhuman primate populations. This study aimed to allow valid comparisons across different primate species by employing a quantitative Multidimensional Method. A comprehensive range of interactions with both social and non-social targets were considered to verify which aspects might elicit the manifestation of lateralized behaviours underpinned by asymmetrical neuronal functions. Spontaneous activities were observed in two groups of zoo great apes, chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla gorilla), and a group of 3-4 year-old typical pre-school children. Results demonstrated a strong consistency in both human and non-human species for a right-hand/left hemisphere dominance during contact with inanimate targets (i.e. objects and environmental items), suggesting a
evolutionary hemispheric specialization influenced by object animacy. Additionally, both great ape species significantly preferred to keep conspecifics closer than 3 metres to their left during manual activities, suggesting a right hemisphere specialization for emotion processing. Only the silverback gorilla (alpha male) manifested the opposite pattern, potentially related to his hierarchical role within the gorilla society. No side preference was found in typical children however, their young age may indicate that they are still undergoing hemispheric development for emotion processing. This study supports an evolutionary origin of hemispheric specialization underling manipulative and social asymmetric behaviours that occurred prior to the split of humans from great apes.
|
174 |
Implementing evidence-based treatments for developmental dyslexia: a comparison between different approachesPasqualotto, Angela January 2019 (has links)
Developmental Dyslexia (DD) is one of the most common neurodevelopmental disorders across cultures. Children affected by DD struggle to read fluently and/or correctly, despite normal intelligence, the absence of other psychological or neurological symptoms, and standard reading education. Not only does this condition affect academic achievement, but it is also associated with a number of other negative consequences across the lifespan, such as an enhanced risk of psychological distress and mental health problems. Despite considerable efforts to identify the underlying cause of dyslexia, agreement on a single interpretation has not yet been reached. DD is commonly described as a languagerelated disorder, with compromised phonological abilities being considered as the core deficit. Nonetheless, a growing body of evidence supports multifactorial models: reading is a complex cognitive process, involving not only phonological skills, but also auditory sensory processes, visual-spatial abilities, attention and memory. In this regard, various studies have documented a relationship between dyslexia and deficits in the Executive Functions (hereafter EFs), which can be defined as a cluster of general-purpose control mechanisms that modulate various cognitive sub-processes. However, the relationship between cognitive correlates and reading impairments is still a controversial issue. The present project aims to analyse the fundamental characteristics and the efficacy of different rehabilitation methods for Developmental Dyslexia. Although the neurocognitive causes of DD are still hotly debated, researchers agree that the main challenge is the remediation, that is, how to improve children’s reading fluency and accuracy. The most common approach has been to devise sophisticated remediation programs that train sub-skills of reading, especially phonological skills and auditory perception. Despite the promising results, the improvements in these sub-skills do not automatically transfer in better reading abilities in all subjects (especially regarding reading fluency), thus giving rise to the issue related to "non-responders" or "poor responders". Since the present data gives firm indications of the need to individualize intervention based on neuropsychological testing, the aim of this project is to investigate the efficacy of new types of treatment based on a multifactorial, probabilistic, model of the disorder. Consequently, this project consisted of two parts: specifically, in the first study, we compared phonological-based treatment with computerized cognitive training of the executive functions (e.g., attention, working memory, planning, inhibition). The results of this study clearly pointed out an advantage both in terms of improvements in EFs and literacy skills for the group who undertook the Integrated training, i.e., the group that underwent 12 hours of Cognitive training prior to 12 hours of Phonological-based treatment. Next, the second study aimed to explore the efficacy of a video game Skies of Manawak purposefully designed to train several EFs. Indeed, it has been showed that the existing treatments are not sufficiently captivating and motivating and, thus, we developed a tool ex novo in order to obtain overall improvement and higher chances of transfer to untrained tasks. Our goal was to investigate whether playing this video game may enhance EFs following intervention, and whether these improvements transfer to important literacy skills in typically developing (Study 2 – Part A) and dyslexic children (Study 2 – Part B). All children underwent 12 hours of training, distributed over 6 weeks, either on Skies of Manawak or on a control computerized activity (Scratch). Assessments upon training completion indicated greater improvements in executive functioning and reading efficiency after Skies of Manawak than after the control training in both studies. Interestingly, the advantage in reading skills was maintained in a follow-up test 6 months later and seemed to generalize to academic performance (i.e., Italian marks). Overall findings highlighted promising effects of the training programs on children’s cognition, making way for future studies investigating the underlying brain mechanisms and the factors leading to treatment success.
|
175 |
Decoding Auditory Motion Direction And Location In hMT+/V5 And Planum Temporale Of Sighted And Blind IndividualsBattal, Ceren January 2018 (has links)
The research presented in this thesis addresses the neural mechanisms of auditory motion processing and the impact of early visual deprivation on motion-responsive brain regions, by using functional magnetic resonance imaging. Visual motion, and in particular direction selectivity, is one of the most investigated aspects of mammalian brain function. In comparison, little is known about how the brain processes moving sounds. More precisely, we have a poor understanding of how the human brain codes for the direction of auditory motion and how this process differs from auditory sound-source localization.
In the first study, we characterized the neural representations of auditory motion within the Planum Temporale (PT), and how motion direction and sound source location are represented within this auditory motion responsive region. We further explore if the distribution of orientation responsive neurons (topographic representations) within the PT shares similar organizational features to what is observed within the visual motion area MT/V5. The spatial representations would, therefore, be more systematic for axis of motion/space, rather than for within-axis direction/location. Despite the shared representations between auditory spatial conditions, we show that motion directions and sound source locations generate highly distinct patterns of activity.
The second study focused on the impact of early visual deprivation on auditory motion processing. Studying visual deprivation-induced plasticity sheds light on how sensory experience alters the functional organization of motion processing areas, and exploits intrinsic computational bias implemented in cortical regions. In addition to enhanced auditory motion responses within the hMT+/V5, we demonstrate that this region maintains direction selectivity tuning, but enhances its modality preference to auditory input in case of early blindness. Crucially, the enhanced computational role of hMT+/V5 is followed by a reduced role of PT for processing both motion direction and sound source location. These results suggest that early blindness triggers interplay between visual and auditory motion areas, and their computational roles could be re-distributed for effective processing of auditory spatial tasks.
Overall, our findings suggest (1) auditory motion-specific processing in the typically developed auditory cortex, and (2) interplay between cross- and intra-modal plasticity to compute auditory motion and space in early blind individuals.
|
176 |
Constructing multiple objects across space and timeMuschter, Evelyn January 2018 (has links)
For us to interact with our environment we must have an understanding of the location and properties of the objects within it over time. Incoming stimuli from different sensory modalities continuously provide information. In order to create a coherent percept, it is necessary to combine these sensory signals in the brain into a single representation of an object or event. Temporal integration, the process of combining information over time is one important prerequisite for it. Likewise, multisensory integration, the process of combining information from different sensory modalities to generate a coherent percept is of great importance. Furthermore, as our environment is not static but dynamic it is necessary to combine sensory information over time and space. Despite, the ever-increasing neuroscientific results, much about the underlying brain mechanisms remains unknown. This thesis describes an effort of understanding how sensory information are integrated in the brain and what effects attention has on how we integrate multiple objects in space and time.
Chapter 1 introduces the reader to the existing literature on neural oscillations, specifically alpha band frequency, which is hypothesized to play a critical role in temporal processing and attention. This is followed by a review of the literature on temporal integration and the theoretical background of multisensory integration. The following chapters will report the three studies conducted: Chapter 2 describes the first study, a MEG study that investigates the role of alpha oscillations in temporal integration. Chapter 3 reports the second MEG study, which focuses the role of attention to modality in multisensory integration. Chapter 4 presents the third study, a behavioral oscillations study, which focuses on the role of neural oscillations in selective attention in a dynamic scene. Finally, Chapter 5 summarizes all the findings from this research.
|
177 |
Attentional Mechanisms in Natural ScenesBattistoni, Elisa January 2018 (has links)
The visual analysis of the world around us is an incredibly complex neural process that allows humans to function appropriately within the environment. When one considers the intricacy of both the visual input and the (currently known) neural mechanisms necessary for its analysis, it is difficult not to remain enchanted by the fact that, even though the signal that hits the retina has a tremendous amount of simple visual features and that is ever changing, ambiguous and incomplete, we experience the world around us in a very easy, stable and straightforward manner. So much effort has been put into the study of vision, and despite the enormous scientific advances and important findings, many questions still need answers.
During my years spent as Ph.D. student, I investigated some questions related to top-down attentional mechanisms in real-world visual search. Specifically, Chapter 2 and 3 address the processing stage of preparation, by investigating the characteristics of attentional templates when preparing to search for objects in scenes; Chapter 4 addresses the stage of guidance and selection, by investigating the temporal course of spatial attention guidance; and finally, Chapter 5 addresses the identification phase, by investigating the temporal dynamics of size-constancy mechanisms in real-world scenes.
To anticipate some results, we proposed that attentional templates in real-world visual search tasks are based on category-diagnostic features and code the expected target size/distance. In the context of the attentional guidance and selection stage, we demonstrate that attention spatially focuses on targets around 240ms, following category-based attentional modulations appearing at 180ms after scene onset. Finally, we propose that size constancy mechanisms appear before 200ms post-scene. This is in line with the expectation that a coarse identification of an object, including its size, should be computed before spatially focusing attention onto the target. Together these studies improve our understanding of top-down attentional processes engaged in real-world visual search, and raise some questions which future research could address.
|
178 |
The effects of counterfactual comparison on learning and reasoningTimberlake, Benjamin January 2019 (has links)
How humans make choices in uncertain and competitive situations is a key determinant of viability and successful living. Improving those choices requires sometimes encountering undesirable outcomes and avoiding them, eventually even anticipating them in novel situations. Learning depends on making choices, encountering errors and updating evaluations of options. Various models extended from the reinforcement learning framework compared to human behavior describe in part how individuals heterogeneously make choices. To peer into the components of these mechanisms, strategic games that emulate real-world situations provide measurable and manageable environments in which to examine slight differences in choice behavior among different people. Such differences may be endogenous to participants (e.g. age or learning disposition) while others derive from external events (e.g. emotional induction or brain stimulation). We contrasted such behavior in three situations involving learning or competition, leveraging differences in age, emotional induction and brain stimulation. We aimed to describe the variations in choice behavior across these differences and investigated, when possible, how prior conditions generated a transfer of learning from one domain to another. The work here builds on recent investigations of neural mechanisms underlying choice behavior during strategic or competitive interaction.
|
179 |
Network Level Representation of Conceptual ContentAglinskas, Aidas January 2019 (has links)
Our ability to store knowledge and represent the world within our minds has spanned multiple disciplines (philosophy, psychology, neuroscience). Currently, theories of human conceptual knowledge suggest that human representation of the world is widely distributed across the brain. Regions involved in sensory/motor simulation as well as amodal systems contribute to our flexible ability to manipulate knowledge. A detailed account of how the overall human semantic system works at a network level is still lacking. To begin our investigation into how knowledge is distributed across brain networks, we will first consider a specific kind of knowledge - person related knowledge. Chapter 2 will look at the behavioural indicators of person-knowledge organisation. We will ask participants to judge explicit/subjective similarity between different person-knowledge domains: social, physical, biographical, episodic and nominal knowledge. This will allow us to investigate whether these processes are independent or related to each other. We will then compare these judgements to implicit similarity measures to see whether correlated patterns of responses or reaction are informative about cognitive similarity. Chapter 3 will look at how the brains core/extended system for face perception coordinates across the aforementioned person-knowledge domains. We will investigate the representational similarity of different person-knowledge domains in individual regions, and crucially - across the network as a whole. This will allow us to address whether cognitions are localised in individual regions or distributed across the whole network. Chapter 4 will investigate the stability of network organisation when going across modalities. Extended system for face perception has been shown to be recruited during familiar name reading. We will ask whether network-level patterns of activation during person-knowledge remain stable across input modalities. Chapter 5 will generalize the network-level approach to investigate broader semantic categories. We will interrogate how diverse regions activated during semantic processing, interact during processing of naturally occurring conceptual categories. We will use a corpus derived semantic distance model and compare it to individual region activity to that of the network overall. We will ask whether information about conceptual distance between categories is contained within individual regions or arises as a product of coordinated effort across the network.
Combined, evidence presented in this thesis speak to the distributed nature of cognitive representation. Different kinds of person-knowledge and object categories are highly linked and rely on overlapping neural substrates. We demonstrate that instead of being specialised for particular tasks, brain areas involved in meaning extraction tend to be involved in most kinds of conceptual processing. Individually regions have slight cognitive tunings and can be geared towards specific cognitions. Differences in person- knowledge and object categories emerge as a product of the coordinated interplay between multiple brain regions.
|
180 |
\"Constantes de acoplamento a partir das regras de soma da QCD\" / The coupling constants in QCD sum rulesSilva, Rômulo Rodrigues da 29 June 2005 (has links)
Usamos as regras de soma da QCD para obter a massa dos pentaquarks \" \'teta\' POT.+\"(1540) e \"\'ksi\' POT.--\" (1862), a largura de decaimento da \"\'teta\' POT.+\" e a constante de acoplamento e fator de forma presentes no vertice J/ \'psi\' \"DD POT.*\". No estudo dos pentaquarks, usamos dois tipos de campos interpolantes contendo dois diquarks altamente correlacionados. Obtemos as massas consistentes com os dados experimentais, porém esta regra de soma têm uma grande contribuição do contínuo e a OPE não é muito boa. Obtivemos uma largura de decaimento compatível com os valores experimentais desde que sejam subtraídos diagramas que representam a \" \'teta\' POT.+\" como um estado ligado K - n. No estudo do vértice vertice J/ \'psi\' \"DD POT.*\" calculamos o fator de forma e a constante de acoplamento, considerando três casos: D off-shell, \"D POT.*\" off-shell e J/ \'psi\' off-shell. A constante de acoplamento é a mesma nesses três casos, porém o fator de forma depende da escolha da partícula off-shell, onde para a J/ \'psi\' off-shell o fator de forma é bem mais duro que o fator de forma obtido para os outros casos. Também comparamos os nossos resultados com outros métodos: o modelo de quark méson constituintes e o modelo de quarks relativísticos constituintes / We use the QCD sum rules to obtain the masses of the pentaquarks _+(1540) and _−−(1862), _+ decay width and the coupling constant and the form factor for the J/ DD* vertex.In the study of the pentaquarks, we use two kinds of interpolating fields, containing two highly correlated diquarks. We get the masses in a good agreement with the experimental value, but this sum rule has a large continuuum contribution and the OPE convergence is not so good. We get the decay width compatible with the experimental value, since we subtract the diagrams that represent _+ as a K − n bound state. In the study of J/ DD* vertex, we calculate the form factor and the coupling constant considering three cases: D off-shell, D* off-shell and J/ off-shell. The coupling constant is the same in those three cases, however the form factor depends on the choice of the particle off-shell, where for the J/ off-shell the form factor is much harder than the form factor obtained for the other cases. We also compare our results with other methods: the constituent quark meson model and the relativistic constituent quark model.
|
Page generated in 0.0604 seconds