2 - A Model of Mental Functioning

Summary

The first important step in the search for effective methods for assessing variations in some supposed quality or characteristic is to formulate a systematic conception of the nature of that entity. In the case of dynamic assessment, we are trying to assess variations in ability – specifically, ability to perceive, think, learn, and solve problems in logical ways. In other words, we are asking how to assess mental functioning; therefore, a model of mental functioning is necessary. Without such a model, attempts at assessment would be unsystematic, even chaotic, inconsistent, and ultimately extremely difficult. In this chapter, we present a model that represents our systematic view of the nature and development of human ability.

There are essentially two ways in which one can view the nature of mental functioning. The first is to ask questions such as, “What is ability, what are its components, origins, and correlates?” In other words, one can try to define the nature of the latent variable, that special quality of human ability that is unobservable and by any direct means immeasurable, whose existence must be inferred from its presumed effects on and relationships to other, more observable variables. In the assessment of individual differences in intelligence, for example, the latent variable is intelligence, whereas the score on an intelligence test, often transformed into IQ, is the manifest variable, the observable and measurable datum on the basis of which we make inferences about the latent variable.