Date of Award

Summer 8-2021

Document Type


Degree Name

Doctor of Philosophy (PhD)

First Advisor

Tilman Sheets


ABSTRACT Radicals are characteristics that impact psychometric properties, such as item difficulty in tests. Within the mental-rotation test literature, occlusion and structure have been shown to contribute to item difficulty but require further study to be used within the context of automatic item generation (AIG). This study investigated whether high or low occlusion functions as a meaningful radical for Shepard-Metzler Mental Rotation Test (SMMRT) items. Thirty-two items containing computer-generated images of 3D block figures were administered to a sample of 180 participants on MTurk. After cleaning and removing careless responders from the sample, the data for 70 participants were analyzed using a 2 X 3 factorial ANOVA. Support for the hypotheses was not found; however, interesting responding patterns are observed due to high and low levels of stack occlusion. This pattern is further investigated in the discussion. The possible reasons for the response pattern are discussed, along with general recommendations and study limitations. Directions for future research are also provided.