Date of Award

Summer 2018

Degree Type


Degree Name

Doctor of Philosophy (PhD)



Committee Chair

Alen Hajnal

Committee Chair Department


Committee Member 2

Donald Sacco

Committee Member 2 Department


Committee Member 3

Richard Mohn

Committee Member 3 Department

Educational Research and Administration

Committee Member 4

Gabor Legradi


Perceiving distance is at the heart of everyday actions like reaching for a cup of coffee. This action may depend on the biomechanical restrictions of the actor (arm-length), the physical distance of the cup, and environmental variables such as surface luminance and texture. Four experiments were conducted to investigate the roles of two environmental variables (surface luminance and surface texture discontinuities) and two movement variables (average magnitude head displacement and the multifractal structure of head motion) in the perception of object reachability in virtual reality. Results suggest that surface texture discontinuities and overall surface luminance affect reaching judgments in different contexts, with exploration patterns modulating each effect. Luminance was a stronger factor than discontinuity, and average magnitude head displacement modulated the effects of the environmental variables more than multifractality. In complex stimulus conditions, dynamic parameters (e.g., movement) predicted perceptual responses above and beyond static parameters alone. In addition, the temporality of environmental variables appears to influence the modeling of the perceptual response based on the conjecture that discontinuity is necessarily explored over time and space, whereas homogeneous luminance does not have to be. In the context of reaching tasks in virtual reality, more movement appears to generate richer optic structure helping to reveal the effects of surface texture variables in judging object reachability.