Author

Daniel Hipp

Date of Award

2015

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

Gerhardstein, Peter

Second Advisor

Inhoff, Albrecht

Third Advisor

Kurtz, Kenneth J.; Yin, Lijun

Abstract

Visual perception depends fundamentally on statistical regularities in the environment to make sense of the world. One such regularity is the orientation anisotropy typical of natural scenes; most natural scenes contain slightly more horizontal and vertical information than oblique information. This property is likely a primary cause of the “oblique effect” in visual perception, in which subjects experience greater perceptual fluently with horizontally and vertically oriented content than oblique. However, recent changes in the visual environment, including the “carpentered” content in urban scenes and the framed, caricatured content in digital screen media presentations, may have altered the level of orientation anisotropy typical in natural scenes. Over a series of three experiments, the current work aims to evaluate whether “digital” visual experience, or visual experience with framed digital content, has the potential to alter the magnitude of the oblique effect in visual perception. Experiment 1 established a novel eye tracking method developed to index the visual oblique effect quickly and reliably using no overt responding other than eye movements. Results indicated that canonical (horizontal and vertical) contours embedded in visual noise were detected more accurately and quickly than oblique contours. For Experiment 2, the orientation anisotropy of natural, urban, and digital scenes was analyzed, in order to compare the magnitude of this anisotropic pattern across each image type. Results indicate that urban scenes contain exaggerated orientation anisotropy relative to natural scenes, and digital scenes possess this pattern to an even greater extent. Building off these two results, Experiment 3 adopts the eye tracking method of Experiment 1 as a pre- post-test measure of the oblique effect. Participants were eye tracked in the contour detection task several times before and after either a “training” session, in which they played Minecraft (Mojang, 2011) for four hours uninterrupted in a darkened room, or a “control” session, in which they simply did not interact with screens for four hours. It was predicted, based on the results of Experiment 2, that several hours of exposure to the caricatured orientation statistics of the digital stimulus would suffice to alter the magnitude of participants’ oblique effect, as indexed by the difference in the post-test relative to the pre-test. While no accuracy differences were observed in this primary manipulation, detection speed for canonical contours did alter significantly in the Minecraft subjects relative to controls. These results indicate that the oblique effect is quite robust at the level of visual contours and is measurable using eye tracking, that digital scenes contain caricatured orientation anisotropy relative to other types of scenes, and that exposure to naturalistic but caricatured scene statistics for only a few hours can alter certain aspects of visual perception.

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