THEORIES OF PERSONALITY

Theories of personality

Theories of personality

Introduction

Much of research examining the acquisition of motor behaviors in infancy and childhood has focused on the “development” of action systems. These action systems include such complex behaviors as walking ([Thelen & Cooke? 1987 and Thelen & Ulrich? 1991])? reaching ( [Savelsbergh et al.? 1997]; [Thelen & Smith? 1994])? and grasping (Newell? Scully? Tennebaum? & Hardiman? 1989; [Van Hof et al.? 2002]).

The focus in motor development research has traditionally been on trying to understand the “process of development?” with emphasis on careful description of the emergence of a particular behavior.1 These careful descriptions were often quite elaborate consisting of many “developmental” stages with particular behaviors viewed as “maturing” at particular ages in young children ( [Gesell? 1929 and McGraw? 1943. McGraw? M. B. (1943). The neuromuscular maturation of the human infant. New York? NY: Columbia University Press.McGraw? 1943]).

For the most part? the behaviors of focus were classified as “phylogenetic” and fundamental to the survival of the species. These age-based descriptions lead to the creation of “motor milestones” that can be found in any developmental textbook (see [Thelen and Adolph? 1992]? for a discussion of Gesell's role in the creation of these milestones). [Von Hofsten? 1993] has suggested that “age norms are important for helping us to form expectations about age-specific performance” (p. 110)? but the focus on age norms can be problematic.

The focus on age-specific changes implies that the emergence of the motor milestones is driven by maturational changes common to all members of the species. Description of motor milestones as relatively stable and predictable has served to reinforce this assumption. Indeed? the whole idea that performance might be age specific assumes a level of consistency across children; one that it is hard to imagine could be accounted for by anything other than a similar maturational process driving change in all children. We argue that this traditional perspective has treated “development” as equivalent to maturation? which makes the reification of age-based norms seem reasonable. In our view they are not. Rather one of the central arguments of our approach is that we need to move away from age-based norms and their implicit maturational assumptions.

[Von Hofsten? 1993] has suggested a number of additional limitations in using age norms. First? norms are highly dependent on the population that provides the norming sample. Even a cursory examination of the motor development literature and of the “norming” samples used in many standardized tests suggest that these norms are most applicable to infants and children of predominantly white? middle-class families in the United States. As [Thelen and Adolph? 1992] discuss? Gesell used highly restrictive sampling in the creation of his developmental norms and more alarmingly these norms still serve as the basis for a number of standard assessment tools. Restrictive norming samples severely limit the usefulness of an assessment tool for children who vary from the norm because these are by definition likely to be outside the “norm” and thus look “delayed” in some aspect of ...