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Title page for ETD etd-09132017-215522


Type of Document Dissertation
Author Park, Young Eun
URN etd-09132017-215522
Title The Role of Stimulus Form in Visual Working Memory for Orientation
Degree PhD
Department Psychology
Advisory Committee
Advisor Name Title
Frank Tong Committee Chair
Geoffrey F. Woodman Committee Member
Joo-Hyun Song Committee Member
Randolph Blake Committee Member
Keywords
  • perceptual organization
  • visual working memory
  • visual short-term memory
  • working memory capacity
  • orientation perception
  • Gestalt
  • perceptual grouping
Date of Defense 2017-08-30
Availability restricted
Abstract
Visual working memory refers to our ability to actively maintain and manipulate visual information about stimuli that are no longer in view. A prominent theory proposes that there is a fundamental limit on the number of visual objects that can be actively held in mind. An underlying assumption is that these capacity limits are invariant to the specific visual properties of the stimulus to be encoded. This longstanding assumption is critically evaluated in three studies presented in this dissertation, which investigate the impact of the physical appearance of stimuli on the information capacity of visual working memory. The first study provides evidence that visual working memory capacity is greatly enhanced for line orientation compared to grating orientation because multiple line orientations can be perceptually grouped into higher-order patterns. The second study demonstrates that visual working memory capacity for line orientation continually increases as more items are presented in the memory array, resulting in a progressively larger advantage in memory performance for line orientation over grating orientation with increasing set size. I show that the observed changes in information capacity across different set sizes, as well as across stimulus types, can be well accounted for by a novel model that incorporates visual grouping into the existing discrete-slots model of visual working memory. In the final study, I find that working memory performance varies systematically across randomly generated line and grating displays. To determine whether this variability in performance across displays arises from perceptual organization processes, I develop a model that quantifies multiple perceptual grouping cues in each display and predicts display-specific memory performance based on the combined strengths of these grouping mechanisms. This Gestalt-inspired model can successfully predict human performance, accounting for a major proportion of variance in working memory performance across displays. Together, these findings highlight the crucial role of stimulus factors and perceptual grouping mechanisms in determining the storage efficiency of visual working memory. By combining behavioral experiments and computational modeling, the present work provides novel insights into the nature of capacity limits in visual working memory.
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