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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)
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)