The LAS is an assessment system for scoring verbal performances. It is grounded in the theoretical traditions of James Mark Baldwin and Jean Piaget. Although it owes a great deal to these early theorists, it has been directly informed by two more recent developmental models—Fischer's Dynamic Skill Theory and Commons' Model of Hierarchical Complexity.

The LAS is a general developmental scoring system. Its scoring criteria are domain independent, referring to logical structure and hierarchical order of abstraction rather than particular conceptual content. In a sense, the Lectical analyst "looks through" the content of a given performance in order to identify its underlying structure. It can be employed to score any verbal performance. In fact, the system and its precursors have been used to score a wide range of behaviors, including logico-mathematical reasoning, social and moral reasoning, evaluative reasoning, and primate behavior.

Publications are available on the DTS website.

Use of this web site is free and open to anyone. However, it is illegal to claim to be a LAS analyst without certification from The Developmental Testing Service, LLC. It is similarly illegal to claim that data were scored with the LAS unless they were scored by a certified LAS analyst. We protect the LAS as a means of standardizing Lectical™ assessments. If you would like us to keep you informed about the LAS, our research, and our assessments, sign up here:

This manual is composed of several sections. We suggest you start by reading the pages on origins and vocabulary under the scoring tab in the main menu. If you are unfamiliar with hierarchical complexity theory, you may also find it useful to read some of the papers in the references lists. Two papers in particular (both in the"our work" file under the references tab)—The shape of development and Developing conceptions of authority and contract—provide a good introduction to our construct and its use as part of a broader methodology.Once you have familiarized yourself with the origins of our work and have brushed up on the vocabulary, go on to the method section. Here you will find information about how we score texts and how we use the LAS to address questions about the relation between developmental level and particular conceptual content. A few examples showing how conceptions develop over time are included in this section, but many more can be found under the examples tab. The instruments and research pages provide summary information about diverse applications of the LAS to primary and applied research.

Mind, Brain, and Education (MBE) is a growing field in psychology that integrates research and thought in cognitive psychology, brain science, and education. In the research section, we present results from a project in which we examined how students learn skills for thinking about the relation among mind, brain, and education. To learn more about this important new field, go to the IBMES web site or the MBE site at Harvard.