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attentional control of spatial perception
Title
The attentional control of spatial perception.
Creator
Balz, Gunther William, Florida Atlantic University, Hock, Howard S.
Abstract/Description
When perceivers examine a visual scene, they can control the extent to which their attention is either narrowly focused or spread over a larger spatial area. The experiments reported in this dissertation explore the consequences of narrow vs. broad attention for simple spatial discriminations as well as more complex cooperative interactions that are the basis for the self-organization of coherent motion patterns. Subjects' attentional spread (narrow or broad) is manipulated by means of a...
Show moreWhen perceivers examine a visual scene, they can control the extent to which their attention is either narrowly focused or spread over a larger spatial area. The experiments reported in this dissertation explore the consequences of narrow vs. broad attention for simple spatial discriminations as well as more complex cooperative interactions that are the basis for the self-organization of coherent motion patterns. Subjects' attentional spread (narrow or broad) is manipulated by means of a primary, luminance detection task. In conjunction with the luminance detection task is a secondary, spatial discrimination or detection task, which differs in the four reported experiments. In Experiment 1, the discrimination of misalignment of two visual elements is enhanced by narrowly focused attention. In Experiment 2, discrimination of horizontal spatial separation of two visual elements is improved for small inter-element distances by narrow attention and for relatively large inter-element distances by broad attention. Experiment 3 shows that the inter-element distance among counterphase-presented visual elements for which unidirectional and oscillatory motion patterns are observed with equal frequency depends on subjects' attentional spread. Narrow attention favors the oscillatory pattern and broad attention favors the unidirectional pattern. Experiment 4 shows that attentional spread has a minimal effect on the detection of motion, and, additionally that attentional effects on simple spatial judgments (Experiments 1 and 2) are too small to account for the large shift in the equi-probable boundary of reported unidirectional and oscillatory motion patterns found in Experiment 3. Therefore, it is concluded in conjunction with Hock and Balz's (1994) differential gradient model, that attentional spread influences the self-organization of unidirectional and oscillatory motion patterns through its effects on the relative strength of facilitating and inhibiting interactions among directionally selective motion detectors.
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Date Issued
1994
PURL
http://purl.flvc.org/fcla/dt/12392
Subject Headings
Attention, Selectivity (Psychology), Visual perception, Space perception
Format
Document (PDF)
effects of standard and deviant tones on event-related brain potentials and reaction-times to visual stimuli
Title
The effects of standard and deviant tones on event-related brain potentials and reaction-times to visual stimuli.
Creator
Fernandez, Mercedes, Florida Atlantic University, Nash, Allan J.
Abstract/Description
This research investigated whether choice reaction time (RT) measures and the P300 component of the event-related brain potential (ERP) could be employed to index the attentional resources associated with performing two near-simultaneous tasks. Specifically, this study investigated the effects of auditory tones on the ERPs and RTs associated with a visual stimulus when the stimuli in both modalities were presented in close temporal proximity. The hypothesis that the ERPs and RTs elicited by...
Show moreThis research investigated whether choice reaction time (RT) measures and the P300 component of the event-related brain potential (ERP) could be employed to index the attentional resources associated with performing two near-simultaneous tasks. Specifically, this study investigated the effects of auditory tones on the ERPs and RTs associated with a visual stimulus when the stimuli in both modalities were presented in close temporal proximity. The hypothesis that the ERPs and RTs elicited by the deviant visual stimulus would index the processing demands associated with the auditory modality was confirmed. In general, greater P300 amplitude associated with one task indicates diminished P300 and poorer performance on a second task. The results indicate that P300 may be a sensitive indicator of shared processing resources when two tasks are performed near simultaneously.
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Date Issued
1995
PURL
http://purl.flvc.org/fcla/dt/15122
Subject Headings
Selectivity (Psychology), Evoked potentials (Electrophysiology), Visual perception, Signal detection (Psychology)
Format
Document (PDF)
Cyclical Variations in Object and Spatial-based Attention
Title
Cyclical Variations in Object and Spatial-based Attention.
Creator
Ray, Subhosit, Sheremata, Summer, Florida Atlantic University, Department of Psychology, Charles E. Schmidt College of Science
Abstract/Description
Spatial-based attention is shown to vary in strength over short intervals of time. Whether object-based selection also has similar temporal variability is not known. Egly, Driver and Rafal (1994) demonstrated using 2-rectangle displays how both spatial and object-based selection engages in processing of a visual scene. In Experiment-1 using the 2-rectangle paradigm we measured temporal variability of target detection by presenting targets at a variable SOA. In Experiment-2, we used 4-squares...
Show moreSpatial-based attention is shown to vary in strength over short intervals of time. Whether object-based selection also has similar temporal variability is not known. Egly, Driver and Rafal (1994) demonstrated using 2-rectangle displays how both spatial and object-based selection engages in processing of a visual scene. In Experiment-1 using the 2-rectangle paradigm we measured temporal variability of target detection by presenting targets at a variable SOA. In Experiment-2, we used 4-squares to preclude any object-based selection and measured temporal variability in target detection at similar locations as in Experiment-1. We found target detection to be periodic in delta and theta hertz rhythm in both Experiment-1 and Experiment-2 upon comparing corresponding cue-valid and same-object locations. Similar spectral profiles across experiments indicate a split-spotlight of spatial attention that rhythmically monitors cue-valid and other invalid locations. Future experiments are needed to determine whether object-based selection is periodic in nature.
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Date Issued
2020
PURL
http://purl.flvc.org/fau/fd/FA00013563
Subject Headings
Attention, Visual Perception, Space perception, Selective attention, Selectivity (Psychology), Visual system
Format
Document (PDF)
THE INFLUENCE OF CONTEXT AND PERCEPTUAL LOAD ON OBJECT RECOGNITION
Title
THE INFLUENCE OF CONTEXT AND PERCEPTUAL LOAD ON OBJECT RECOGNITION.
Creator
Islam, Mohammed, Barenholtz, Elan, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Psychology
Abstract/Description
Forster and Lavie (2008) and Lavie, Lin, Zokaei and Thoma (2009) have demonstrated that meaningful stimuli, such as objects, are ignored under conditions of high perceptual load but not low. However, objects are seldom presented without context in the real world. Given that context can reduce the threshold for object recognition (Barenholtz, 2013), is it possible for context to reduce the processing load of objects such that they can be processed under high load? In the first experiment, I...
Show moreForster and Lavie (2008) and Lavie, Lin, Zokaei and Thoma (2009) have demonstrated that meaningful stimuli, such as objects, are ignored under conditions of high perceptual load but not low. However, objects are seldom presented without context in the real world. Given that context can reduce the threshold for object recognition (Barenholtz, 2013), is it possible for context to reduce the processing load of objects such that they can be processed under high load? In the first experiment, I attempted to obtain similar findings of the aforementioned studies by replicating their paradigm with photographs of real-world objects. The findings of the experiment suggested that objects can cause distractor interference under high load conditions, but not low load conditions. These findings are opposite of what the perceptual literature suggests (e.g., Lavie, 1995). However, these findings are aligned with a two-stage dilution model of attention in which information is first processed in parallel and then selectively (Wilson, Muroi, and MacLeod, 2011). Experiment 2 assessed if this effect was specific to semantic objects by introducing meaningless, abstract objects. The results suggest that the dilution effect was not due to the semantic features of objects. The third experiment assessed the influence of context on objects under load. The results of the experiment found an elimination of all interference effects in both the high and low load conditions. Comparisons between scene-object congruency revealed no influence of semantic information from scenes. It appears that the presentation of a visual stimuli prior to the flanker task diluted attention such that the distractor effects previously observed in the high load condition were minimized. Thus, it does not appear that context reduced the threshold for object recognition under load. All three experiments have demonstrated strong evidence for the dilution approach of attention over perceptual load models.
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Date Issued
2019
PURL
http://purl.flvc.org/fau/fd/FA00013319
Subject Headings
Perception--Research, Selective attention, Form perception, Context effects (Psychology)
Format
Document (PDF)
The effect of competition on men’s sexual behavior
Title
The effect of competition on men’s sexual behavior.
Creator
Gorelik, Gregory, Bjorklund, David F., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Psychology
Abstract/Description
Evidence in humans suggests that men are especially competitive with other men over resources and, if successful, are valued as attractive mating prospects by women. Previous studies also show that men experience an increase in testosterone following a win and a decrease in testosterone following a loss. If an increase in testosterone following a victory is an evolved physiological response aimed at readying a man for an increase in mating opportunities, then experimentally manipulating...
Show moreEvidence in humans suggests that men are especially competitive with other men over resources and, if successful, are valued as attractive mating prospects by women. Previous studies also show that men experience an increase in testosterone following a win and a decrease in testosterone following a loss. If an increase in testosterone following a victory is an evolved physiological response aimed at readying a man for an increase in mating opportunities, then experimentally manipulating competitive outcomes should differentially affect men’s sex-drive. One-hundred thirteen men were randomly assigned to experience a win, a loss, or no competitive feedback. Participants’ sex-drive was gauged by their responses to photographs of women of differential attractiveness. Results showed that only single men exhibited a higher sex-drive in the winning condition, followed by the control and losing conditions, respectively. Limitations and practical applications to decreasing instances of rape and sexual coercion are discussed.
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Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00004198
Subject Headings
Mate selection -- Psychological aspects, Psychoneuroendocrinology, Sports -- Physiological aspects, Sports -- Psychological aspects, Testosterone -- Physiology
Format
Document (PDF)
Large-Scale Cortical Functional Connectivity Underlying Visuospatial Attention
Title
Large-Scale Cortical Functional Connectivity Underlying Visuospatial Attention.
Creator
Meehan, Timothy Patrick, Bressler, Steven L., Florida Atlantic University, Charles E. Schmidt College of Science, Center for Complex Systems and Brain Sciences
Abstract/Description
The endogenous, or voluntary, control of visuospatial attention relies upon interactions within a frontoparietal dorsal attention network (DAN) and this network’s top-down influence on visual occipital cortex (VOC). While these interactions have been shown to occur during attention tasks, they are also known to occur to some extent at rest, but the degree to which task-related interactions reflect either modulation or reorganization of such ongoing intrinsic interactions is poorly understood....
Show moreThe endogenous, or voluntary, control of visuospatial attention relies upon interactions within a frontoparietal dorsal attention network (DAN) and this network’s top-down influence on visual occipital cortex (VOC). While these interactions have been shown to occur during attention tasks, they are also known to occur to some extent at rest, but the degree to which task-related interactions reflect either modulation or reorganization of such ongoing intrinsic interactions is poorly understood. In addition, it is known that in spatial neglect—a syndrome following unilateral brain lesions in which patients fail to attend to the contralesional side of space—symptom severity covaries with disruptions to intrinsic interhemispheric interactions between left and right homologous regions of the DAN; however, similar covariance with disruptions to intrahemispheric interactions within the DAN, and between the DAN and VOC, has not been demonstrated. These issues are addressed herein via the measurement of both undirected and directed functional connectivity (UFC, DFC) within the DAN and between the DAN and VOC. UFC and DFC were derived from correlations of, and multivariate vector autoregressive modeling of, fMRI BOLD time-series, respectively. Time-series were recorded from individuals performing an anticipatory visuospatial attention task and individuals at rest, as well as from stroke patients either with or without neglect and age-matched healthy controls. With regard to the first issue, the results show that relative to rest, top-down DAN-to-VOC influence and within-DAN coupling are elevated during task performance, but also that intrinsic connectivity patterns are largely preserved during the task. With regard to the second issue, results show that interhemispheric imbalances of intrahemispheric UFC and DFC both within the DAN and between the DAN and VOC strongly correlate with neglect severity, and may co-occur with functional decoupling of the hemispheres. This work thus demonstrates that the intrinsic functional integrity of the DAN and its relationship to VOC is crucial for the endogenous control of visuospatial attention during tasks, and that the compromise of this integrity due to stroke likely plays a role in producing spatial neglect.
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Date Issued
2016
PURL
http://purl.flvc.org/fau/fd/FA00004613
Subject Headings
Cognitive neuroscience., Sensorimotor integration., Space perception., Selectivity (Psychology), Recognition (Psychology), Brain mapping.
Format
Document (PDF)
Visual wavelength discrimination by the loggerhead turtle, Caretta caretta
Title
Visual wavelength discrimination by the loggerhead turtle, Caretta caretta.
Creator
Young, Morgan, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Little is known about the visual capabilities of marine turtles. The ability to discriminate between colors has not been adequately demonstrated on the basis of behavioral criteria. I used a three-part methodology to determine if color discrimination occurred. FIrst, I exposed naèive, light-adapted hatchlings to either a blue, green or yellow light. I manipulated light intensity to obtain a behavioral phototaxis threshold to each color, which provided a range of intensities we knew turtles...
Show moreLittle is known about the visual capabilities of marine turtles. The ability to discriminate between colors has not been adequately demonstrated on the basis of behavioral criteria. I used a three-part methodology to determine if color discrimination occurred. FIrst, I exposed naèive, light-adapted hatchlings to either a blue, green or yellow light. I manipulated light intensity to obtain a behavioral phototaxis threshold to each color, which provided a range of intensities we knew turtles could detect. Second, I used food to train older turtles to swim toward one light color, and then to discriminate between the rewarded light and another light color ; lights were presented at intensities equally above the phototaxis threshold. Lastly, I varied light intensity so that brightness could not be used as a discrimination cue. Six turtles completed this task and showed a clear ability to select a rewarded over a non-rewarded color, regardless of stimulus intensity. Turtles most rapidly learned to associate shorter wavelengths (blue) with food. My results clearly show loggerheads have color vision. Further investigation is required to determine how marine turtles exploit this capability.
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Date Issued
2012
PURL
http://purl.flvc.org/FAU/3352879
Subject Headings
Color vision, Visual discrimination, VIsual perception, Selectivity (Psychology), Photoreceptors, Loggerhead turtle, Orientation, Sea turtles, Orientation, Animal navigation
Format
Document (PDF)