Initial validation of a test of spatial knowledge in anatomy

The authors have developed HERCULES, a computer-based test designed to assess the spatial, non-verbal components of knowledge in anatomy. The test consists of two tasks, each requiring subjects to estimate the vertical level in the body of a set of color, cross-sectional images. In Task 1, subjects make the estimate based on a limited number of clues, where each clue is an anatomical structure that appears in the cross-section. In Task 2, subjects estimate the level based on a view of the cross-section with all structures shown. A validation study of this test using six images for each task was performed with preclinical medical students, fourth year medical students, and experienced teachers of anatomy as subjects. Results indicate that the exercise is at an appropriate level of difficulty and that a somewhat longer test than used in this study would be adequately reliable for use in actual assessment. The test appears to discriminate the expert faculty from more novice students and thus exhibits an aspect of validity that is very important in assessment exercises of this type.