Abstract
This study examined the understanding of marked relational terms and the negative term (“not”) in the “Considering Two Things Task” (with the series of height) and in the “Considering Two Dimensions Task” (with the matrix of the series of height and thickness). Subjects were 7-, 8-, and 9-year-olds. In the Considering Two Things Task, when a single marked term or negative term was used, the task was not difficult. But when marked terms and/or negative terms were combined, the task became difficult. Decentration hypothesis was supported rather than reversability hypothesis. In Considering the Two Dimensions Task, the difficulty increased as the number of marked terms or the negative terms increased. Considering two dimensions of a thing (if not considering all elements) was easier than considering a single dimension of two things. Considering two things or two dimensions in the series task was more difficult than in the classification task. Markedness, negation, considering two dimensions and considering two things were supposed to need perceptual decentration.
