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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Influences of context on object detection and identification in natural scenes

LaPointe, Mitchell R. P. January 2016 (has links)
The way we perceive complex visual scenes has been an area of much research and debate. Many studies have found that the context of a scene is used to guide attention to important and relevant areas of a scene. Other studies, however, have found that objects that are incongruent with the scene context capture attention. These contradictory findings have been found both within and across tasks. The purpose of the present research was to reconcile these contradictory results. Two processes were identified as underlying complex scene perception: object detection and object identification. Further, the current research demonstrates the relative weighting of these processes differs according to task demands; some tasks weight object detection more heavily, whereas other tasks weight object identification more heavily. Moreover, it was demonstrated that the weighting of these processes can be manipulated within a task in such a way as to produce either congruency benefits or costs. Finally, in circumstances in which processing is weighted in favour of object detection, it was demonstrated that eye gaze, and presumably overt attention, is captured by semantically incongruent objects early into scene perception. The current research helps our understanding of complex scene perception by reconciling contradictory findings reported in previous studies. In particular, two processes were identified: object identification, which relies on a congruent context, and object detection, which relies on an incongruent context. In this way, past experience may promote efficient scene perception by promoting the use of regularities in the environment (e.g., congruent context), but also leaving the attention system sensitive to areas of the scene that contradict the expectations set by the context (e.g., incongruent objects). / Thesis / Doctor of Philosophy (PhD) / The way that we perceive and create mental representations of our visual world has been an area of debate in cognitive psychology. The research attempting to address these issues has reported contradictory findings. For example, some studies have shown that the context of a scene is important for efficient perception of that scene and its parts. Other studies, however, have shown that the context of a scene can undermine efficient perception of scenes. The current research identifies two distinct processes that underlie complex scene perception. One process appears to benefit from a congruent context, whereas the other appears to benefit from an incongruent context. Further, the weighting of these two processes can produce context congruency benefits in some experimental situations and congruency costs in others. Finally, it appears as though when processing is weighted towards congruency costs, attention is attracted to incongruent objects early into scene processing.
52

Lecture listening skills : their nature and relation to achievement /

Rogers, George Walter January 1959 (has links)
No description available.
53

Perceptual difficulty effects on memory: The benefit of incongruency for subsequent retention

Davis, Hanae January 2020 (has links)
This thesis examined the intersection between processing difficulties at encoding and subsequent retention. A number of reported effects describe the finding of better memory performance for items that were difficult to process in an earlier study phase compared to items that were easy to process—a finding broadly captured by the desirable difficulty principle (Bjork, 1994; Bjork & Bjork, 2011). The Introduction provides an overview of several of these effects, as well as an evaluation of theoretical frameworks that may help us understand the cognitive processes that may be shared across them. The empirical work focuses specifically on one memory effect—better recognition for targets formerly presented on incongruent as opposed to congruent trials in a selective attention task. The effects reviewed in the Introduction, including the one studied in the three empirical chapters, all involve difficulty in processing target information in a relatively simple perceptual identification task. The work covered in this thesis demonstrates that manipulations of perceptual features reliably benefit subsequent memory when the difficulty directs additional processing toward higher-order features. Furthermore, the memory test must appropriately tap into these conceptual feature representations at retrieval. The implications of these findings is discussed in the context of the desirable difficulty literature, as well as the attention and memory literatures more broadly. / Dissertation / Doctor of Philosophy (PhD) / The way we pay attention to information influences how well we remember it later. Although this link seems intuitive, research on this topic has led to a complex literature with mixed results and several different theoretical perspectives. Specifically, several memory effects have been reported that describe better memory performance for items that were difficult to process during learning compared to items that were easy to process. The theoretical goals of this thesis were to review several of these memory effects and to offer a more unified conceptual understanding of their underlying cognitive processes. The empirical goal of this thesis was to examine one such memory effect and place the findings in the context of the conceptual frameworks discussed.
54

Identification of Anxiety Endophenotypes Using Multidimensional Measures of Attention

Strege, Marlene Vernette 19 January 2017 (has links)
The relationship between attention bias and anxiety has been robustly supported across paradigms and disorders; however, most published studies have ignored the known multidimensional nature of attention, and instead proceeded in measuring attention bias as a unitary construct, resulting in a lack of clarity regarding which attentional mechanisms contribute to specific manifestations of anxiety. In the current study we addressed this by collecting response latency data on three basic attentional processes, (1) attentional orienting, (2) attentional disengagement, and (3) attentional control to evaluate their relationship to specific anxiety symptoms. In a final sample of 149 college undergraduates, who either completed the computer tasks in-lab (N = 28) or online (N = 121), we used an unsupervised clustering approach (k-means clustering) to assign individual cases to clusters, depending upon their performance on measures of attention. We used a supervised machine learning approach (random forest), to cross-validate the unsupervised classification results. Anxiety symptoms were then set as predictors, predicting cluster membership using multinomial logistic regression. With the unsupervised k-means clustering approach, we found four clusters in the data. The random forest algorithm suggested variable prediction accuracy, dependent upon cluster size. Anxiety symptoms were unrelated to attention cluster membership. Study results were limited, which may be influenced by potential data collection and analytic factors. / Master of Science
55

The Effects Of The Allocation Of Attention Congruent With Lateralized Cognitive Tasks On EEG Coherence Measurements

Hill, Cynthia DeLeon 05 1900 (has links)
The single task condition of the Urbanczyk and Kennelly (1991) study was conducted while recording a continuous electroencephalographic (EEG) record. Attention was allocated by instructed lateral head orienting and eye gaze either congruently or incongruently with lateralized cognitive tasks. Thirty university subjects retained a digit span or a spatial location span for a 20 second retention interval. EEG data were extracted from the 20 second retention intervals and interhemispheric coherence was calculated for homologous sites in the temporal, parietal and occipital regions of the brain. There was a main effect for group, with congruent orienting producing greater coherence values than incongruent orienting. This effect of attention on alpha coherence values was found in the low alpha (8-10 Hz) frequency band. This provides evidence that the lower alpha frequency band is reflective of manipulations of attention. The higher coherence measures for the congruent orienting group indicates that homologous regions of the two hemispheres are more coupled into a single system when lateralized attention activates the same hemisphere performing the cognitive task. In the higher alpha frequency band (11-13 Hz) group, sex, site and task interacted. This provides evidence that the higher alpha band is more affected by cognitive processing of the specific task undertaken. An interhemispheric brain system, affected by the lateral orientation of attention, may underlie psychometric intelligence's general “g” ability (Spearman, 1927.)
56

Measuring attention: An evaluation of the Search and Cancellation of Ascending Numbers (SCAN) and the short form of the Test of Attentional and Interpersonal Style (TAIS)

Greher, Michael R. 05 1900 (has links)
This study found a relationship between the Search and Cancellation of Ascending Numbers (SCAN), Digit Span, and Visual Search and Attention Test (VSAT). Data suggest the measures represent a common construct interpreted to be attention. An auditory distracter condition of the SCAN did not distract participants, while the measure exhibited ample alternate forms reliability. The study also found that the Test of Attentional and Interpersonal Style (TAIS) short form poorly predicted performance on the Digit Span, VSAT, and SCAN. Although the TAIS exhibited good internal consistency, the items likely measure the subjective perception of attention. Furthermore, discriminant and convergent validity of the TAIS were found to be poor.
57

Concentration construct refinement and scale development /

Krawietz, Sabine Anna. January 2007 (has links)
Thesis (M.A.)--University of West Florida, 2007. / Title from title page of source document. Document formatted into pages; contains 73 pages. Includes bibliographical references.
58

Selective attention control facilitates learning from task-relevant competing information during childhood and adulthood

January 2021 (has links)
archives@tulane.edu / Learning environments are complex, dynamic settings that contain multiple sources of information that compete for our attention resources. Researchers and practitioners argue that selective attention control is critical for effective learning, as selective attention allows individuals to stay focused on primary task goals and ignore task-irrelevant competing information. However, research with older adults has shown that increased attention to competing information can also benefit learning when this competing information is relevant to ongoing learning tasks. We examined the extent to which individual differences in selective attention skills influenced individuals’ learning from task-relevant competing information. Across three experiments we examined these effects at multiple developmental time points in the context of an experimental learning task and in computer-based learning environments. In Experiment 1, 4- to 8-year-old children completed a selective attention task that included competing information that was relevant for an ongoing learning and memory task. Children with better selective attention skills showed enhanced learning from the task-relevant competing information when they could efficiently complete the attention task and visually sample the relevant information. Experiment 2 examined 3- to 5-year-old children’s learning from science video lessons that varied in the amount of lesson-relevant vs. -irrelevant competing information available. Children with better selective attention skills preferentially attended to lesson-relevant competing information when both relevant and irrelevant information was present during the lessons, which promoted enhanced learning of lesson content. Finally, Experiment 3 examined the impact of multiple competing visual features (i.e., instructor videos, visual cues) on young adults’ learning from pre-recorded video lessons. Adults’ learning depended on both their selective attention skills and their perception about the relevance of these visuals for their learning. Individuals with better selective attention showed enhanced learning from lessons that included multiple competing visual features considered task-relevant by the learner. Attention control is typically equated with the ability to focus on primary target information while ignoring competing information. However, the current results suggest that selective attention control also involves the ability to efficiently shift across multiple relevant inputs in the environment, allowing for effective learning from both target material and task-relevant competing information. / 1 / Jill L King
59

Does Infants' Socially-guided Attention Uniquely Predict Language Development?

Wu, Qiong 24 January 2014 (has links)
The purpose of this study was to examine whether infants' social attention, as well as their joint attention behaviors uniquely predicted emerging language abilities. This longitudinal study examined attention regulation skills, joint attention behaviors, infants' expressive/receptive language (current), emerging communication abilities at 16- and 17-month-old (time 1); expressive/receptive language (subsequent) at 18- 19-month-old (time 2). Infants' sustained attention was measured by their attention control to a central stimulus in the presence of a distracter competing for their attention. Dynamic human face (upright, inverted) and abstract display with their matched voice tracks were used to separately measure infants' attention regulation to different types of events. Infants' sustained attention was estimated by their latencies away from central stimuli to distracters, as well as their fixation duration and gaze count on central events and distracters. It was found that infants' latency away from the abstract figure toward the distracter was the only variable that significantly negatively predicted current expressive vocabulary. Initiating joint attention was observed to significantly predict infants' abilities in current receptive vocabulary. The emerging language communication ability predicted expressive vocabulary at two times. In addition, infants' fixation and count to the upright speaker's face and eyes contributed significant amount of variance in initiating joint attestation. The fixation and gaze count on the distracter in the upright condition significantly predicted infants' emerging language skills. / Ph. D.
60

Studies of Visual Attention

Bora, Archana 17 June 2009 (has links)
Aim The experiment proposed to study the effect of sustained visual attention in an effective visual field of 40 degrees, in cued and uncued conditions with different set-sizes. Methods The participants had a normal contrast and visual acuity with normal ocular/general health. The experiments were performed both for central (0 - 20degrees) and peripheral (>20 – 50 degrees) visual fields. The targets were presented with valid and invalid cued conditions in different set-sizes of 500, 1000 and 2000. The targets were Gabor gratings oriented at 90 or 180deg subtending a minimum angle of resolution (MAR) ranging from 1.5-10minarc at 25cm. The spatial frequency of the Gabor ranged from 1- 29cycles/degrees and contrast from 20-100%. The observer had to identify the Gabor with horizontal grating and register the response. The accuracy and the reaction times for the targets were evaluated. Results The central targets had lower reaction times and high accuracy compared to the peripheral targets. There was a significantly increasing eccentricity effect as the targets were displayed much peripherally. It was less with presentation of valid sustained cues but it was not eliminated. The diminishing contrast of the target had a significant increase in reaction times and reduced accuracy. The effect of increasing number of items in the display didn’t show any significant increase in reaction time, i.e. there was no “set-size effect” seen both central and peripheral targets. The valid cues improved the performance with lower reaction times, compared to the neutral cued conditions, in each of the different experiments and resulted in an improved accuracy in both the central and peripheral visual field. Conclusion Visual attention is affected by contrast, target size and spatial gratings. Reaction time is high and accuracy less for low contrast targets, high spatial frequency and larger set-size, except for set-size 2000 in the central field where it was seen that the reaction times were reduced. The effect is consistent in both central and peripheral visual fields. The set-size also has an effect on the reaction times and on accuracy. The effects are more pronounced in the peripheral visual field.

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