The literature suggests a "concrete" to "abstract" hierarchy in concept acquisition. However, typical tests do not reflect this hierarchy. Studies have been reported in which an "abstract" option for an item was included in with a "concrete" option and with distractors. This procedure assumes that "abstract" and "concrete" behavior is on a common dimension. This study tests this assumption. Two tests were built: in one, each item had a "concrete" right answer with two distractors; in the other an "abstract" right answer appeared with two distractors. These tests were factor analyzed with subtests from the Iowa Tests of Basic Skills and the Cognitive Abilities Tests. The two experimental tests loaded on the first factor, suggesting a common dimension. (Author/GDC)