This article reviews two aspects of human learning: (1) people draw inferences that appear to rely on hierarchical conceptual representations; (2) some categories are much easier to learn than others given the same number of exemplars, and some categories remain difficult despite extensive training. Both of these results are difficult to reconcile…

In this special section, 6 articles address the provocative question of how to determine the boundary between difference and deficiency, for children who differ from the mainstream in some way--language, hearing, cultural background, socioeconomic status, or social understanding. Our commentary considers these articles in light of current models…

Extends dynamic model of cognitive growth proposed by van Geert in three directions: (1) added a term to consider exposure to material to be learned; (2) developed method to apply model to cross-sectional studies; and (3) developed procedure to scale cognitive abilities tests with items of varying difficulty. Tests model with 2- to 15-year-olds'…

The authors argue that imitation is a flexible and adaptive learning mechanism in that children do not always reproduce all of the details they can from a demonstration. Instead, they vary their replications depending on their interpretation of the situation. Specifically, the authors propose that when children do not understand the overall reason…

Potential benefits of using item response theory in test construction are evaluated, based on the experience and evidence accumulated during 9 years of using a three-parameter model in the construction of major achievement batteries. Specific benefits covered include obtaining sample-free item calibrations and item-free person measurement,…

This paper argues that no single measurement strategy serves all purposes and that applying methods and techniques which allow a variety of data elements to be retrieved and juxtaposed may be an investment in the future. Item response theory, Rasch model, and latent trait theory are all approaches to a single conceptual topic. An abbreviated look…