Sources of Difficulty in Imagining Cross Sections of 3D Objects

A novel 30-item multiple choice psychometric test was developed to measure individual differences in a spatial visualization task that involves identifying the cross section that results from the intersection of a cutting plane and a geometric solid. An initial study with 59 participants established the internal reliability and external validity of the test. Items in the test varied in complexity of the geometric solid and orientation of the cutting plane. Cutting plane affected performance such that people made more errors when the cutting plane was oblique to the main axes of the object than when it was orthogonal. Effects of cutting plane also interacted with the type of geometric structure. Low-spatial participants had consistently poorer performance. Analyses of their errors suggested that sources of difficulty in this task included failure to shift mental perspective from the current viewpoint to imagine the cutting plane from another orientation and failure to decompose the complex solids into geometric primitives.