Date of Award

Winter 12-15-2019

Author's School

Graduate School of Arts and Sciences

Author's Department


Degree Name

Doctor of Philosophy (PhD)

Degree Type



I have previously identified a novel perceptual manipulation that enhances learning of some complex natural categories, and the current dissertation aims to uncover its mechanism. Specifically, learning of categories of tropical fish was enhanced when learned through small pictures (about 2º) compared to large pictures (about 19º). Through analyzing the previous results and extant theories in various domains, I identified two potential mechanisms through which this small-picture-size advantage manifested. The perceptual precedence hypothesis postulates that the processing of local dimensions is prioritized in large pictures and the processing of global dimensions is prioritized in small pictures. Therefore, small picture size should enhance category learning only when a global dimension is diagnostic (e.g., the exterior shape in the tropical fish categories). The increased effort hypothesis postulates that because small pictures are harder to process than large pictures, it creates a metacognitive sense of disfluency, and that perceptual disfluency engages learners in a more effortful and analytical processing of the stimuli. Thus, this theory predicts that small picture size should enhance category learning whether the diagnostic dimension is local or global. Two experiments directly pitted these unique predictions by the two theories against each other; participants studied category structure with either a global diagnostic dimension or local diagnostic dimensions. These experiments not only replicated the small-picture-size advantage, but also showed a large-picture-size advantage when local dimensions were diagnostic. The findings supported the perceptual precedence hypothesis and suggested that the picture-size effect is category-structure-specific rather than category-structure-general. The effects of the size manipulation on learners’ metacognition is also discussed.


English (en)

Chair and Committee

Mark A. McDaniel

Committee Members

Richard A. Abrams, Julie M. Bugg, Jeffery M. Zacks, Andrew C. Butler,


Permanent URL: https://doi.org/10.7936/qak4-bb24

Included in

Psychology Commons