Necessary But Not Sufficent: The Respective Roles of Single and Multiple Influences on Individual Development [Hardcover]

Theodore D. Wachs (Author)

Book Description

Publication Date: December 1999

In this provocative book, Wachs challenges fellow developmentalists and researchers to reconsider simple approaches, arguing that they are unproductive and poor predictors of outcome. Instead, he proposes a view of development in which variability is thought of as the action of linked influences over time, from domains as diverse as evolution, genetics, neurology, nutrition, and the child's immediate and wider environment. The book musters an impressive array of evidence from a variety of disciplines to demonstrate that, while influences from a particular domain may be necessary to cause a particular outcome, they are rarely sufficient, in and of themselves. Countering the arguments of those who protest that it is neither realistic nor cost-effective to design research based on multiple influences, Wachs argues that this can and must be done, and suggests ways of doing so.

Product Details

• Hardcover: 439 pages
• Publisher: American Psychological Association (APA); 1 edition (December 1999)
• Language: English
• ISBN-10: 1557986118
• ISBN-13: 978-1557986115
• Product Dimensions: 10.1 x 7.2 x 1.4 inches
• Shipping Weight: 2.8 pounds
• Average Customer Review: 5.0 out of 5 stars  See all reviews (2 customer reviews)
• Amazon Best Sellers Rank: #1,587,729 in Books (See Top 100 in Books)

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4 of 4 people found the following review helpful:

5.0 out of 5 stars A "Necessary But Not Sufficient" Review, July 24, 2001

By 

"sdrichie" (Oxford, MS United States) - See all my reviews

This review is from: Necessary But Not Sufficent: The Respective Roles of Single and Multiple Influences on Individual Development (Hardcover)

To begin, one of the most striking elements of this book is the disregard of inappropriate parsimony in developmental psychology, an area of research that has traditionally involved an attempt to "boil down" the pertinent influences that affect human development. Wachs, on the other hand, serves his readers a delectable plate full of relevant research findings that point to a much more sophisticated web of relations between a myriad of variables shown to be related to some component of human development. Although such an approach to explaining human development seems a bit overwhelming at first, in addition to the over seventy pages of references he has reviewed to author this book, Wachs' exhaustive review of single and multiple developmental influences is both informative and thought provoking. Wachs divides the book into chapters that each outline a specific area believed to have an impact on development. For example, in chapter two Wachs discusses the influences of both evolution and ecology. Much of the reviewed research suggests that evolutionary influences, such as our own selection processes, may serve as "blueprints" which can be "actualized" by more immediate influences (p. 27). In addition, Wachs outlines the affects of ecological influences on human development and finds such results as the correlation between children living in cold climates, where parents may tightly wrap them in warm clothing, and the restriction of their motor activity and influences on their personality development. In chapter three he acknowledges the necessary influence of genetic, neural, and hormonal factors through a review of a great amount of relevant research. He explains that although genes code for particular characteristics and functions, they have only an indirect impact on human development, as they are associated with the conditions of external factors, such as the proximal and distal environmental influences summarized in chapters six and seven. In these chapters Wachs reviews the influence of external conditions, namely proximal and distal factors, on human development. Some proximal factors having an indirect impact on human development are caregiver beliefs, parental rearing styles, and environmental chaos, which is a comprised of many environmental conditions, such as high levels of noise, lack of both temporal and physical structure in the home, and unpredictability in the child's environment. In comparison, distal influences are associated with more long-standing factors, such as characteristics of culture, social class, and parental work situation. An important point to address here, a point about which Wachs continually warns the reader, is that although such evolutionary, ecological, proximal, and distal factors are necessary influences on human development, none, in and of themselves, sufficiently explain the individual variability in human development. In other interesting chapters Wachs outlines many more factors related to human development. For example, in chapter four he explains the impact of nutritional supplementation on the development of malnourished children. Perhaps even more impressive than the exhaustive reviews of the multiple influential factors associated with human development is Wachs' systematic approach to explaining how these factors actually related to and affect one another in regard to the developing human. These linkages are depicted in chapter eight, and Wachs uses the term "midlevel processes" to refer to those processes common to the developmental influences outlined in chapters two through seven. For instance, multiple influential factors can be functionally related, which refers to the impact on development by the combination of independent influences. Functional linkages can produce developmental variability in different ways, such as through "additive coaction," influence of summed independent factors, or through "interaction," differential reaction of people with differing attributes to similar factors (p. 186). In addition to functional linkages, Wachs explains the impact of structural linkages, which hold that developmental influences "neither act nor occur in isolation" (p. 191). These types of linkages explain occurrences such as the covariance among the multiple developmental influences, for which it is important to account when studying the relationships between developmental processes. For instance, research has shown that there is covariance between "child oppositional behavior at school, greater peer rejection, less on-task classroom behavior, and poorer learning" (p. 196). Through this example it is evident that the influences vary with one another to produce the developmental outcomes under study and that it is not simply the influence of a single factor that produces a certain developmental outcome. Essentially, Wachs attempts to persuade his readers to endorse this systematic approach when studying the influences of the factors related to human development, requiring the acknowledgement of covariates, summations, differential reactivities, and more. More specifically, in a three-level model Wachs outlines how a person functions within an intricate system throughout the course of their lives, and he denotes several properties of the individual that are similar to properties of general systems. For example, he explains that individuals grow and differentiate over time, much like systems. He adds that people, like systems, have an organized way of functioning that is due to influences of both the external environment and the person's own self-regulating strategies. Although more similarities are illustrated, Wachs incorporates an even more engaging component of the systematic approach to explaining the developmental processes of a human. This component is related to the stabilizing affects of particular influences as dominant themes within a person's life begin to develop. Wachs calls these dominant characteristics in a person's life "stabilized central attractors," which are "densely linked to other multiple elements or influences characterizing an individual and toward which the individual's developmental trajectory converges" (p. 290). Even through this complicated systematic explanation it is clear that many factors are necessarily related to human development, but are not sufficient influences in and of themselves. In summation, in reading this book I found that it is this complexity that is most interesting and gives the systematic approach to understanding the multiple influences on human development an interesting edge in the arena of human development as studied in the field of developmental psychology.

2 of 2 people found the following review helpful:

5.0 out of 5 stars Amazing scholarship, November 6, 2006

By 

Karen Franklin "Forensic Psychologist" (El Cerrito, CA, USA) - See all my reviews
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This review is from: Necessary But Not Sufficent: The Respective Roles of Single and Multiple Influences on Individual Development (Hardcover)

I was amazed by Theodore Wachs' knowledge base and scholarship. He surveys a vast and complex landscape to explain just about everything we know about what makes people turn out the way they do. Psychologists such as myself are often called upon to explain why a person ended up in a particular situation, and Wachs' book helps me to answer this question within the limits of today's scientific knowledge while avoiding the temptation to oversimplify by attributing outcome to one or two obvious causes. Wachs explores influences on development ranging from evolutionary and genetic to environmental (both proximal and distal). Even more difficult, he provides a model for integrating multiple influences on human outcome. An amazing and well thought out treatise!