Developmental Psychology: An Evolutionary Perspective

By M.D. Rutherford

This textbook introduces the field of developmental psychology from an evolutionary and adaptationist perspective. This perspective allows us to make sense of the interaction between the developing child and the environment in which the child is developing. It allows us to ask why the human mind is designed the way it is, what functions psychological processes serve, and how our human psychology was adaptive in the environment in which our ancestors evolved. A second advantage to an evolutionary framing is pedagogical. This book has a strong thesis: That nature and nurture work together by design during development. This thesis is supported in every content chapter—from perceptual development to language development to gender development—giving students a strong framework with which to link the empirical reports. M.D. Rutherford is Canada Research Chair in Social Perceptual Development and Professor in the Department of Psychology, Neuroscience and Behaviour at McMaster University.

• Language: English
• Publisher: Lulu Publishing Services
• Release date: Sep 16, 2016
• ISBN: 9781483456218

Book preview

Developmental

Psychology

An Evolutionary Perspective

M.D. Rutherford

Copyright © 2016 M.D. Rutherford

All rights reserved. No part of this book may be reproduced, stored, or transmitted by any means—whether auditory, graphic, mechanical, or electronic—without written permission of both publisher and author, except in the case of brief excerpts used in critical articles and reviews. Unauthorized reproduction of any part of this work is illegal and is punishable by law.

The information, ideas, and suggestions in this book are not intended as a substitute for professional advice. Before following any suggestions contained in this book, you should consult your personal physician or mental health professional. Neither the author nor the publisher shall be liable or responsible for any loss or damage allegedly arising as a consequence of your use or application of any information or suggestions in this book.

ISBN: 978-1-4834-5623-2 (sc)

ISBN: 978-1-4834-5622-5 (hc)

ISBN: 978-1-4834-5621-8 (e)

Library of Congress Control Number: 2016913979

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Lulu Publishing Services rev. date: 09/02/2016

Contents

1. What Is Developmental Psychology?

What Is Developmental Psychology?

What Is Development?

Why Study the Developmental Psychology of Children?

The Early History of Developmental Psychology

An Evolutionary Perspective on Development

Current Issues in Developmental Psychology

Organizing Themes

2. Theories and Methods in Developmental Psychology

Piaget’s Theory of Cognitive Development

Associationism and Social Learning Theory

Systems Theories

Evolutionary Psychology

Methods of Developmental Psychology

Within- and Between-Subjects Design

Techniques for Developmental Research

3. Foundations of Development

A Modern Understanding of Evolution

Darwin’s Problem: Blending Inheritance

Mendelian Inheritance

Chromosomes, Genes, and Alleles

Evolutionary Processes

What Does DNA Do Anyway?

Interactionism: The Bidirectional Influences of Developmental Resources

Genetic Effects Are Not Just One-to-One

Meiosis, Conception, and Pregnancy

Birth

Brain Development

Early Motor Development

4. Heritability and IQ

Understanding Nature and Nurture; Understanding Causality

Heritability

The Heritability Statistic

Intelligence

IQ as a Case Study of Heritability

What Heritability Is Not

Norm of Reaction

5. Perceptual Development

The Function of Perception: Adaptive Behavior

Early Competencies and Interests

Prenatal Perceptual Development

Postnatal Perceptual Development

Constancies

The Nobel Prize-Winning Work of Hubel and Wiesel: Experience-Expectant Development

Visual Deprivation and Development in Humans

Associationist Accounts of Visual Development

What Would Developmental Systems Theorists Say?

Face Perception

Sleeper Effects

6. Concepts, Categories, and Essences

What Are Categories and Concepts?

Instinct Blind to Concepts

Universality of Children’s Concepts

The Function of Categories and Concepts

Function Matters in Early Concept Formation

The Classic View of Categories

A Prototype and Family Resemblance View

What Would Piaget Say about Children’s Categorization?

Concept Development

Essences and Essentialism

Basic Levels and Hierarchical Categorization

Neuropsychological Perspective on Concepts

What Would Evolutionary Psychologists Say about Children’s Categorization?

What Would Associationists Say about Children’s Categorization?

7. Language Development

Language Is Part of Our Psychology

What Would Systems Theorists Say about Language Acquisition?

Language as a Case Study in Evolutionary Psychology

Noam Chomsky and the Language Acquisition Device

What would Piaget say about Language Acquisition?

Infant Speech Perception

Proto-Babbling and Babbling

Word Learning

Social influences on Children’s Language Acquisition

Learning Grammar

What Would Associationists Say about Language Acquisition?

Critical Periods for Language Learning

Children Generate Language

Language Is Species-Specific

Can a Gene Cause the Development of Grammar?

8. Knowledge Acquisition

The Acquisition of Knowledge

Prepared Learning

Core Knowledge

Areas of Core Knowledge

A Cross-Species Comparison

9. Social Development

Social Contact as a Need

The Social Brain Hypothesis

The Big Brain and Long Childhood

What Would Piaget Say about Social Cognitive Development?

What Would Associationists Say?

Human-Specific Social Cognition

Early Social Cognitive Development

Play

Animacy and Intentionality Perception

Early Perception of Social Categories

Theory of Mind

Autism: What If There Were No Theory of Mind?

10. Emotional Development

Facultative Adaptations

Learning about One’s Own Context

Psychological Adaptations for Culture

Defining Emotion

Emotional Development

Temperament

Personality

Attachment

Deprivation

The Sense of Self Concept and Self Esteem

11. Family and Other Relationships

Protracted Social Development

Humans as Cooperative Breeders

Parenting Styles

The Hadza, the !Kung, and Ecologically Dependent Parenting Strategies

Families as Systems

Peers as the Agents of Socialization

Birth Order

12. Sex and Gender

Why Look at Gender?

Gender Roles in the EEA

Adaptive Sex Differences

The Development of Sex and Gender

Understanding Gender

Puberty

Views of Gender Development

The Reimer Twins: A Natural Test of the Socialization Theory of Gender

Intersex

The Transgender Experience

Life History Theory

Relative Life Expectancy

Cultural Differences in Mating and Parenting

13. Moral and Prosocial Development

Morality and Prosocial Behavior

Traditional Views on Moral Development

Twentieth Century Views on Moral Development

Turiel’s Social Domain Theory

The Function of Morality

What Would Evolutionary Psychologists Say?

Getting Altruism off the Ground

Early Moral Development

The Development of Social Exchange Reasoning

The Development of Sexual Morals

Teaching Morals

Moral Intuition or Rational Moral Decision-Making?

Do Other Species Have a Moral Psychology?

CHAPTER

1

What Is Developmental Psychology?

Opening Vignette: 7 Up! to 56 Up

In the fall of 1962, Canadian journalist Paul Almond went to Britain to make films. He noticed that although England’s Labour Government had claimed to have created a classless society, social class in England was actually a good predictor of a child’s opportunities and eventual outcome. In a unique use of film, Almond and collaborator Michael Apted created a longitudinal series, following a group of children at regular intervals over a long period of time in order to test the hypothesis that class influences were so strong, at least in England, that a child’s outcome could be determined at birth.

The film 7 Up! introduces fourteen 7-year-olds, selected to represent a range of classes. Three boys came from the wealthy suburb of Kensington, another attended a prestigious boarding school, and one girl came from a wealthy background and was filmed at her boarding school. Some children came from a working-class neighbourhood in London, and one child came from London’s East End, known for overcrowded, underprivileged living conditions and high crime rates. Two boys came from a charity-based boarding school, another from a small farm in Yorkshire, and two more were from middle-class suburban schools near Liverpool.

A new film was produced every 7 years, 56 Up having been released in 2012. The films show the development of these children, including their career paths, marital status, and parenting styles. As the series’ creators suspected, the films show quite a lot of class stability, but there were some surprising exceptions. Two of three boys from a wealthy pre-preparatory school ended up in a prestigious preparatory school and attended Cambridge or Oxford. In contrast, a middle-class child who appeared happy and hopeful at age 7 was homeless and unemployed by age 21 but had found some stability in housing and employment by the time 49 Up was filmed. One boy from the East End moved into a more middle-class lifestyle and currently owns two homes.

By reading about the numerous influences on a child’s development and the way these influences work together to create a developing person, you, like the creators of the Up series, will discover that examining data from real developing children can answer your questions but may also yield some surprises.

Chapter Outline

What is Developmental Psychology?

What is Development?

Why Study the Developmental Psychology of Children?

The Early History of Developmental Psychology

Recent Modern Developmental Psychology

An Evolutionary Perspective on Development

Current Issues in Developmental Psychology

Organizing Themes

Learning Objectives, Outcomes

The purposes of this chapter are to introduce you to developmental psychology and to prepare you to read about research in the field of developmental psychology, starting with a description of the discipline and its history.

You will read about the classic nature vs. nurture question, dating back to the earliest writings about human development, and how our contemporary understanding of human psychology as a product of evolution by natural selection gives us a solid starting point for thinking about nature and nurture working together rather than independently.

You will be introduced to the current issues in developmental psychology. To some extent, these issues can be understood as debates, motivated by a central disagreement. Understanding these disagreements may help you understand the arguments and theories you will encounter in developmental psychology.

You will read the five organizing themes that are central to this book. If you understand these themes early in this book, you will more easily understand the ideas in this book, because these five organizing themes recur over and over throughout.

You will learn how natural selection works and how our psychological processes have resulted from evolution by natural selection. When thinking about what natural selection has designed modern humans to do (from seeing to speaking to parenting), one needs to think of the environment in which the relevant selection pressures acted, the environment of evolutionary adaptedness

(EEA

).

What Is Developmental Psychology?

Development refers to changes across the lifespan. Developmental psychology is the scientific study of changes in psychology and behavior often from the prenatal period to early, but sometimes middle and late, adulthood. Development is a biological process, and will include both normative changes that result in development that is similar across individuals and idiosyncratic changes in which individuals respond to their environment by developing in ways that are adaptive in specific circumstances. Developmental psychology is a division of the study of development that focuses on psychology, and includes all types of psychological development: emotional, social, cognitive, linguistic, moral, perceptual, and conceptual, to name some examples. Developmental psychologists use the scientific method to answer questions about the development of people and sometimes animals. This method involves a consensus about how data is collected, how it is analyzed, and what conclusions are warranted based on the results. Because developmental psychology is a science, the ideas and beliefs within this field change over time as a result of empirical evidence. Scientific research advances our understanding of infants’ and children’s psychological development.

developmental psychology

The scientific study of recurrent psychological changes across the human lifespan, focussing on development from the prenatal period to early, but sometimes middle and late, adulthood.

In the field of developmental psychology, the scientific method can be used for description that is, reporting at what age children typically show particular skills and understandings. This method can also be used for explanation, that is, testing current beliefs (called hypotheses) that predict how changes in a given variable will affect another variable. Hypotheses are educated guesses that can and should be tested. Following the tradition of the scientific method, hypotheses can be wrong, regardless of how widely believed, dearly held, or politically convenient they might be. If the experiments that are designed to test a hypothesis reject that hypothesis, the hypothesis needs to be modified or abandoned.

1.1 Press Pause

Hypotheses are educated guesses that can and should be tested.

Figure11TheScientificMethod.jpg

Figure 1.1 The Scientific Method

The scientific method involves a consensus about how data is collected, how it is analyzed, and what conclusions are warranted based on the results. This figure illustrates the steps involved.

Furthermore, because developmental psychology is a science, what we believe to be true about developmental psychology needs to be consistent with what we know from other branches of science. For example, a hypothesis that is inconsistent with what we know about cell development or genetics cannot be true unless what we know about cell development or genetics is incorrect. Our developmental hypothesis needs to be consistent with what we know about genetics, developmental biology, evolution, biochemistry, and all other branches of science.

Developmental psychology encompasses more than just genetics. It includes a wide range of psychological processes, including motor development, perceptual development, conceptual development, cognitive development, social and emotional development, language development, gender and sexual development, and moral development, to name a few other areas of interest.

What Is Development?

All species go through a process of development, a process of species-typical maturation that involves growth, increasing complexity and, in many species, specialization of functional systems. Development is a scientific field of inquiry not just in psychology and not just in humans, but throughout the field of biology.

Development is, counterintuitively, an inevitable result of the fact that there are accidental deaths. Let’s see how this works. If there were no accidental deaths, then every species would be long-lived, and increasingly so. Accidental deaths result from unanticipated weather or climactic events, injury resulting from activity, or any number of unforeseen catastrophes. Because accidental death does happen, and happens in every species, opportunities for new individuals are created. The death of an individual creates an available niche, and mechanisms for bringing new individuals into the world evolve. Those mechanisms for bringing new individuals into the world are what we call development. For some species, including humans, this means the creation of sex cells and sexual reproduction; in other species, a spore contains the genetic information that is necessary for the next generation.

gamete

One of two sex cells, egg or sperm, that fuse together during fertilization.

adaptation

A trait that is designed and preserved by the process of natural selection because that trait confers a reproductive advantage in the environment in which it evolved.

Intuitively and scientifically development begins when the genome of a new individual is complete. In sexually reproducing organisms, this is marked by conception: the union of two gametes (sex cells) called the egg and the sperm. From there, cellular specialization, systems development, and increasing complexity and functionality unfold through sequential periods of functional specialization that continue into adulthood.

Although the beginning of development is marked by the union of the complete genome, the developing child was designed by natural selection to make use of the resources that were likely available to our ancestors including physical, nutritional, social, and linguistic resources. The developing child was also designed by natural selection to solve age-specific problems, so develops adaptations at the age when the benefit of the adaptation exceeds the cost.

Note the use of the word designed in the previous paragraph. It is common for psychologists and biologists to use this term to describe the process of evolution by natural selection as it creates complex adaptations, that is, traits that are designed and preserved by the process of natural selection because they confer a reproductive advantage in an organism’s current environment. Saying that an organ or mechanism is designed for a certain function does not imply that there was a designer or intention that led to its formation. Natural selection creates results that appear to be designed by an intentional designer, but the intention is illusory. Calling adaptations designed is just shorthand and should be understood as such.

1.2 Press Pause

Development happens in all species because all individuals die, creating a niche for new individuals.

Why Study the Developmental Psychology of Children?

One reason for studying psychological development in children is that it gives us insight into our universal human nature. By studying children in different cultures, or in different socio-economic environments within the same city we can learn which traits are human universals, robust across species-typical environments. We can learn how factors in these environments interact with the developing child to bring about lasting changes, and we can learn how deviations from the environments, whether intentional or accidental, will affect development.

species-typical environment

The environment that provides the features that the genome needs or expects in order to develop typically.

A second reason for studying the developmental psychology of children is that doing so may shed light on adult psychological processes, which may be complex and otherwise difficult to study. For example, studies of language development may shed light on the rules underlying adult language production. Such studies may reveal errors that show that children over-apply a particular rule. If adults make such errors only infrequently, then the rule itself may remain invisible in an adult language study. In addition, observing the development of these processes may yield clues as to components and developmental precursors. For example, does a child have to understand mental representations before they can understand and produce pretend play? A longitudinal study can shed light on this question (Rutherford, Young, Hepburn, & Rogers, 2007).

A third motivation for studying child development is the possibility that, whether as parents, educators, or policy makers, people want to know how their interactions with children affect their development. Does it matter whether a parent speaks to a pre-verbal child? What rewards and punishments should an adult offer to help a child internalize morality? What visual experiences are important to visual development? How should we allocate finite resources toward enriching a school or community? Real-world, practical applications result from reading and research in the area of developmental psychology.

The Early History of Developmental Psychology

Discussions and debates on child development long predate any experimental research in the area. Some of the earliest known writings on child development were those of Aristotle and Plato in the 4th century

B.C.E.

Both Plato and Aristotle believed that children, especially boys, were naturally unruly and aggressive, so discipline and self-control were important parts of childhood education, and both philosophers were interested in asking whether a child’s development could be attributed to inborn factors (nature) or environmental factors (nurture). Aristotle’s writings showed an early recognition of individual differences: Why did one child grow up with a particular set of interests and skills and another child with a different set? He suggested that the ideal education can only be developed if tailored to each individual child.

nativist

One who views development as being driven primarily or exclusively by internal forces. The information needed for development is assumed to exist within the developing child. Often this information is thought to be preserved in the genes

Plato, thought to be the classic nativist, believed that children were born with innate knowledge. Indeed, according to Plato, young children did not need to learn but only had to recollect information that was available. For example, in the first year of its life a baby would recognize an animal as an animal, having that concept innately and not needing any specific teaching or experience in order to understand it.

20319.png

Figure 1.2 Plato and Aristotle

Plato (left) believed that children were born with innate knowledge and that they did not need to learn, but only had to recollect information that was already available from within. Aristotle (right) believed the mind of a newborn baby was a blank slate on which knowledge would be written by experience. These two juxtaposing views are the historical roots of the nature vs. nurture debate.

empiricist

One who believes that all knowledge depends upon direct experience or empirical observation. The newborn’s mind is a blank slate and requires exposure to information in order to gain knowledge.

Even though he was a student of Plato, Aristotle became the classic empiricist, asserting that the mind of a newborn was a blank slate on which knowledge would be written by experience. Everything that a developing child needed to know was available to him in the real world and could be understood simply via empirical observation, according to this perspective. These two juxtaposing views are the historical roots of the nature vs. nurture debate.

1.3 Press Pause

The seeds of the nature vs. nurture debate can be seen in the writings of Plato and Aristotle, from the 4th century B.C.E. Plato is the classic nativist, and Aristotle is the classic empiricist.

THE ENLIGHTENMENT AND CHILD DEVELOPMENT

Early European philosophers were still wrestling with the question of human knowledge acquisition in the 17th and 18th centuries. To a large extent, the empiricist tradition was lauded on the British Isles, and the nativist view, also called rationalism, was supported on the European continent. English philosopher John Locke (1632–1704) was an empiricist like Aristotle and viewed the newborn’s mind as a blank slate or, in Latin, a tabula rasa. Locke rejected the suggestion that infants had any innate knowledge or concepts. He held the extreme view that all knowledge was a result of experience and that the mind simply accepted the knowledge that was imparted by virtue of sensory inputs. Nurture was all-important, parental and societal influences shaped the development of the child, and all knowledge as well as all reason came from experience, according to Locke. Experience was the only avenue to knowledge. Even one’s character was open for shaping: Locke believed that because the child’s mind was a blank slate, the parent could potentially mould and form the child to be whatever type of person the parent desired through means such as reward and punishment, example, and explicit instruction. A child, conversely, could do little to influence his or her own development. Locke discouraged corporal punishment in school, since it might, consequently, have led to a child’s aversion to formal learning. Locke’s empiricist beliefs served as the foundation for 20th-century behaviorists, described below.

According to empiricism, if a person was a talented artist or inventor, his or her childhood environment was to be credited. Similarly, if one grew up to be a criminal, it was due entirely to a poor upbringing. Also important to Locke’s legacy was his belief that all children were created equal. This is a logical implication of the idea that each child’s mind is a blank slate, and the perspective became an important philosophy to American colonists as they developed their new government. That all people are seen as equal in the eyes of North American law can be traced to John Locke.

French philosopher Jean-Jacques Rousseau (1712–1778) is credited with having carried on the nativist tradition. Rousseau opposed the idea that children’s minds were blank slates; instead he thought children had conceptual understandings and knowledge (including concepts of justice and fairness) that unfolded through maturation. Children would, by their own activities and explorations, be largely responsible for their own development. Adult tutoring would only interfere with the child’s natural development, Rousseau believed, although he did acknowledge the role of the environment and the child’s interaction with the environment in the process of maturation.

Rousseau thought that children, noble savages as he referred to them, should therefore be given as much freedom as possible in service of their education. Until the age of 12, when the child reached the age of reason and could choose and discriminate among information sources, they should be left to explore on their own. He illuminated his views on childhood in a novel called Émile (1762), which tells the story of the development of a child from infancy to adolescence. Ultimately, he used the novel as a mechanism for conveying his own child-rearing advice, emphasizing the effects of free exploration over formal instruction.

Because developmental psychology is a science, there came a point when conjecture was no longer productive, and early disagreements about the development of children and the acquisition of knowledge and expertise created a controversy that could only be resolved via empirical research.

1.4 Press Pause

The empirical study of child development started in earnest in the late 19th and early 20th centuries. Around this time, universities began supporting research programs in developmental psychology, and academic journals about the discipline were emerging. Developmental psychology was becoming a genuine and respectable field of scientific inquiry.

EARLY MODERN DEVELOPMENTAL PSYCHOLOGY

Charles Darwin

baby biography

An intensive study first developed by Charles Darwin that describes the activities of an individual baby, typically the scientist’s own child or a close relative.

It may surprise you to know that early modern work in child development was spurred on by none other than Charles Darwin and his theory of evolution by natural selection. In response to his work, contemporary scientists recognized the importance of understanding child development as a window into the nature of the human species. In 1877, Darwin published an article entitled A Biographical Sketch of the Infant, which was a description of his infant son’s development. The method Darwin developed for this intensive study came to be known as the baby biography. One of his observations was the similarity of early prenatal development across the species that he was able to explore. The prediction that followed, that human children would develop in the same way that other young animals develop, turned out to be an inaccurate simplification but prompted some of the first careful observations of human development and children’s behavioral development nonetheless.

Figure13Darwin.jpg

Figure 1.3 Charles Darwin

In 1877, Charles Darwin published A Biographical Sketch of the Infant, the first baby biography. One of Darwin’s observations was the similarity of early prenatal development across the species that he was able to explore.

G. Stanley Hall

G. Stanley Hall (1844–1924) is considered the founder of developmental psychology, having begun the first psychology laboratory in the United States at Johns Hopkins University in the 1880s and being among the first to use a scientific approach to child development. Hall was an early developmental psychologist who was also interested in evolutionary theory. He read and was influenced by the work of Charles Darwin and was inspired by Darwin’s theory of natural selection.

Hall was primarily interested in studying child development and educational psychology. He thought that children should be educated according to their emerging needs and abilities and that these could be illuminated by considering human evolutionary history. He advocated the scientific reconstruction of the evolutionary history of the human mind, human behavior, and human culture and espoused the theory of recapitulation: the idea that developmental changes parallel the species’ changes through evolutionary time.

normative approach

The study of development in which norms or averages are computed over a large population and individual development is compared to these norms.

Hall emphasized the maturational process that characterized child development. He believed that children developed following an inherent plan that would unfold more or less automatically given the proper circumstances (Hall, 1904). Hall conducted the first large systematic study of development in North America and is perhaps most well known for having started the normative approach in which he worked to define the norms of development. He measured the development of large numbers of children, computed averages that represented typical development, and then identified children whose development fell outside of this normal range.

The theoretical ideas that drove Hall’s work, and his belief that development recapitulates evolution, are no longer held in high regard, but his impact on the field is unmistakable. He trained the first generation of developmental psychologists in the methods of research, established scientific journals that served to report research findings in the field, and founded the American Psychological Association, which is still in operation today.

James Mark Baldwin

James Mark Baldwin (1861–1934) was one of the founders of the Department of Psychology at what is now Princeton University. In 1889, he established a laboratory of experimental psychology at the University of Toronto, the first such laboratory in the British Empire. His appointment was controversial, as nativist leanings prevailed in Toronto at the time. He later became a founding member of the American Psychological Association, co-founded the very influential journal Psychological Review and was the founding editor of the still very important Psychological Bulletin. Like Darwin and Hall, he was an adherent of the theory of evolution by natural selection, and believed that the theory could shed light on the study of child development.

Baldwin was one of the first to use experimental methods to examine development in the light of Darwinian thinking. His seminal work Mental Development in the Child and the Race: Methods and Processes (Baldwin, 1895), was the first to report experimental data in the field of developmental psychology.

Baldwin made several important contributions to the early thinking of developmental psychology. First, he proposed a step-wise theory of psychological development. He thought that improvements in thinking occurred in broad and sudden steps, rather than continuously and gradually. This idea was developed more fully by Jean Piaget, as his stage theory (described in the next few pages).

Baldwin tried to extend the theory of evolution by natural selection into the field of developmental psychology, and is today best remembered for the idea that has become known as the Baldwin effect. In describing this effect, Baldwin recognized that a developing organism was designed to respond to the environment during a lifetime, for example by tanning in response to exposure to the sun, growing greater muscle mass in response to exercise, or any type of learning. However, Baldwin also pointed out that this sort of plasticity, including learning, is costly: it involves the development of learning mechanism, the metabolic costs of learning, and a cost of ignorance before the learning is achieved. Baldwin suggested that if some members of a population have achieved the optimal endpoint (they have learned), then there is an evolutionary pressure on others to get to that endpoint. There is now competition to achieve the endpoint more quickly. This evolutionary pressure might, given the correct cost-benefit profile, lead to the evolution of an organism that develops the end state, rather than developing the plasticity or the learning mechanism (Baldwin, 1896). Examples might be bird song (Simpson, 1953) and human language (Pinker & Bloom, 1990).

Arnold Gesell

Arnold Gesell (1880–1961) was a student of G. Stanley Hall. Gesell started the Yale Clinic of Child Development in 1911 and spent the next 50 years there doing research on the normative development of typical children. Like Hall, Gesell’s view of development was that it followed a maturational process, an unfolding of normal biological processes. Gesell believed that for typical healthy children, development would follow a predictable pattern that was the same for each child. Thus, he was very interested in the normative approach and spent much of his career documenting and describing the norms of development.

Using the normative approach, Gesell found a great deal of uniformity in the development of the hundreds of children that he studied. Following his methods, one was able to tell whether or not an individual child was developing normally in areas such as motor, social, and personality development. Gesell was the first person to see value in making this information available to parents so that they could know what milestones to expect with their baby’s age.

1.5 Press Pause

G. Stanley Hall and his student Arnold Gesell started the normative approach. Gesell watched the development of many, many children and documented the age at which skills normally develop.

John B. Watson

John B. Watson (1878–1958) is often called the Father of Behaviorism after the sub-field of psychology that he described, named, and popularized. Of the developmental psychologists who made the field a science, he was the first to follow Locke’s assertion that what drives behavior and shapes development is a person’s learning based on experience. Watson was an empiricist in the extreme, as he believed that variation between individuals was not at all due to any endogenous differences between people but was entirely due to differences in how they were reared. Indeed, he is popularly known for having said

Figure14JohnBWatson.JPG

Figure 1.4 John B. Watson

John B. Watson, the Father of Behaviorism, followed Locke’s tradition. Watson was an empiricist and believed that variation between individuals was not due to any inherent differences between people but was entirely due to how they were reared.

Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I’ll guarantee to take any one at random and train him to become any type of specialist I might select—doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors. (Watson, 1930, p. 82)

In essence, Watson and other behaviorists believed that a person’s (or animal’s) behavior could be entirely controlled via reward and punishment training. The central belief of behaviorism was that behavior is a result of conditioning processes: A person or animal had been conditioned to associate two events (classical conditioning) or a behavior and an outcome (operant conditioning). In chapter 2 we will look at this view in more detail. Watson dismissed the idea that studying cognition or thought was possible or even that it might be scientifically interesting, thinking instead that psychologists should focus only on measurable behavior.

Watson is also famous for his Little Albert experiments, conducted in 1920 at Johns Hopkins University (Watson & Raynor, 1920). In order to demonstrate the classical conditioning of fear, Watson trained an 11-month-old boy Albert (who prior to the experiments showed a typical range of emotions) to fear white rats. It followed, according to Watson, that parents should be able to control children’s behavior by controlling the stimulus and response pairings that the child encounters.

Although behaviorism has lost its former popularity, and the extreme views of empiricism are rejected by contemporary developmental psychologists, Watson did make some lasting and valuable contributions to developmental research. He insisted on objective methods, which made the study of development more rigorous and more interpretable. The rigidity of his experimental design is still important to developmental psychologists today.

Jean Piaget

Jean Piaget (1896–1980) was enormously influential to developmental psychology. It would be impossible to overstate his influence on the field of cognitive development, and therefore his views and research are presented throughout this book, including a broad review in Chapter 2.

Piaget was a Swiss psychologist who worked in and essentially created the field of cognitive development. He was interested in science even as a child, and his early work on animal behavior may have had an influence on his thinking about child development. After earning a

P

h.

D

. in Switzerland, he moved to Paris and was hired to administer intelligence tests to school-aged children. This was his entré into developmental psychology. He noticed not just quantitative differences in responses due to age (older children responded correctly to more questions), but he also noticed qualitative differences (children at different ages saw and understood things differently).

After two years of work in France, Piaget returned to Switzerland and began his own cognitive development studies. He was more interested in examining how children think and how knowledge changes during development than in what children did and did not know. He called this study of knowledge development genetic epistemology.

genetic epistemology

Genetic epistemology, according to Piaget, describes the process of cognitive development from birth through late adolescence.

Piaget’s theory of cognitive development

Piaget described children’s development through stages, which predicted that children attained a certain set of cognitive skills at a certain stage.

clinical method

A research method involving a semi-structured interview. The researcher approaches the interview with a planned set of questions but may have followed up on or probed areas of interest depending upon the child’s responses.

Piaget’s theory of cognitive development was a stage theory: When children attained a certain stage of cognitive development, they were limited to the skills characterized by that stage until they reached the next stage, at which point a whole new set of cognitive skills were available to them. Piaget’s theory is described in much more detail in chapter 2.

In a field that was still new and in need of scientific methods, Piaget was methodologically innovative. Unlike previous developmental psychologists who observed children while trying not to interfere with their behavior, Piaget actually presented children with challenging tasks (e.g., having them sort items into groups) and asked them questions and then had them explain their answers. Thus, Piaget created the clinical method. The clinical method was a research method involving a pre-planned, semi-structured interview in which the researcher may have followed up on or probed areas of interest depending upon the child’s responses. Again, Piaget was more interested in how children think than whether their answers were right or wrong. The clinical method is still in use today.

Piaget’s work did not become influential in North America until the 1960s, both because behaviorism had such a stronghold on the thinking of North American psychologists and because Piaget’s concepts and terms were unfamiliar to them.

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Piaget was the most influential figure in the emerging field of cognitive development.

Lev Vygotsky

Lev Vygotsky (1896–1934) was an early Russian developmental psychologist and a contemporary of Piaget. Unlike Piaget, who had a background in science, Vygotsky’s background was linguistics, literature, and law. Because of his emphasis on social development and the importance of the social context on development, he is described as a social constructivist.

Figure15Vygotsky.jpg

Figure 1.4 Lev Vygotsky

Lev Vygotsky was an influential Russian developmental psychologist. Working in the collectivist Soviet Union, Vygotsky emphasized the influence of culture on a child’s development.

Vygotsky worked in the new Soviet Union, just after Marxism had replaced the czarist system of government. During that historical period, there was a tremendous emphasis on culture, collectivism, and socialism. In this context, Vygotsky developed his theory of social development, which emphasized the influence of culture as well as the influence of other people on a child’s development, knowledge, and thinking.

Vygotsky described and studied the relationship between language development and thought. In contrast to Piaget, Vygotsky stressed the cultural context of a child’s development and the effect that culture could have as the child moved through the stages of cognitive development. Vygotsky was interested in the transmission of cultural values, beliefs, attitudes, and skills to the next generation. He focused on co-operative dialogues between children and their elders as a means of cultural transmission. He thought cultural influence was so strong that it could disrupt the order of the stages, whereas Piaget did not believe that a child could go through the stages in anything but the canonical order.

dialectical process

A process of shared problem-solving.

zone of proximal development

The tasks a child can complete with and without adult support.

Vygotsky thought that much of the child’s cognitive development resulted from the dialectical process, a process of shared problem-solving. In this process, an adult and a child repeatedly work through a problem or task together. At first, the adult takes the lead, performing, modelling, and instructing. Over time the child takes more and more responsibility for executing the task. Eventually, the child internalizes the knowledge and the way of thinking modelled by the adult. The concept of the zone of proximal development, one of Vygotsky’s lasting contributions, was thought to be the child’s growing edge, or next step in development, and describes the tasks a child can complete with and without adult support.

Vygotsky died before ever knowing what an impact he would have on the English-speaking world. His work was not translated into English until the 1960s, after which point it became part of the scientific exploration of child development and subjected to scientific study. Not only did he not live to see his work considered by Western psychologists, but he was also unread in his home country, where his work was banned.

RECENT MODERN DEVELOPMENTAL PSYCHOLOGY

Over the course of the 20th and now 21st century, developmental psychology and theoretical perspectives of developmental psychology have become more complicated and more nuanced, with researchers focusing their careers on sub-areas of the field. In the context of this complexity, the field is no longer characterized by individual thinkers who take the entire field in new directions. That said, there are several people who have contributed substantially to sub-areas of developmental psychology. Here, you’ll read about four such people: Erik Erikson, who laid foundations in the area of personality development, Uri Bronfenbrenner, who created ecological systems theory, Jerome Kagan who started the research area looking at infant temperament, and Walter Mischel who contributed to our understanding of personality development by emphasizing the importance of the situation or context.

Erik Erikson

Erik Erikson was born in Germany to a Danish mother and was raised in Germany by his Jewish mother and step-father. He finished high-school, but never completed university. He did train with Sigmund Freud’s daughter Anna Freud, working with children’ of affluent parents who were undergoing psychoanalysis. With her encouragement, he studied psychoanalysis in Vienna. As Hitler rose to power and burned Sigmund Freud’s works, Erikson converted to Christianity and moved his family to the United States, and subsequently changed his surname to Erikson. Erikson famously described 8 stages of psychosocial development, which characterizes healthy or ideal development from infancy through adulthood. The theory emphasizes the challenges that one will face at each stage, and describes ideal or failed completion of these challenges. Outcomes are always described dichotomously, e.g. as trust v. mistrust or intimacy v. isolation. If a challenge is not surmounted successfully, it is expected to arise again, even if the individual has moved on to a different stage. If successful, the virtue achieved (e.g. competence, love, or wisdom) is carried throughout the rest of one’s life. You will still see Erikson cited as a foundational contributor in discussions about personality psychology or childhood psychoanalysis.

Urie Bronfenbrenner

Urie Bronfenbrenner was born in Moscow, Russia in 1917, but moved with his family to the United States when he was six years old. He earned his doctoral in developmental psychology from the University of Michigan in 1942. Bronfenbrenner created the ecological systems theory of child development. This theory is described in much more detail in Chapter 2, but briefly, it emphasized that the child was growing up in a social system. The child’s development could not be understood without looking at the contexts in which development took place. These contexts included the family, the school, the neighborhood and its institutions, religions, the economy in which the parents earned a living, and various levels of government that created laws and policies that impacted the child. Bronfenbrenner described not just how these contexts affected the child directly, but how the various levels affected one another, as when laws or religious attitudes regarding divorce allow or prevent the child’s parents from dissolving their marriage, for example. In addition to Bronfenbrenner’s systems model, and in some respect as a result of it, he became interested in governmental policies and programs. In the mid 1960’s Bronfenbrenner was invited to join a US Federal panel that was working on the problem of child poverty, and the delivery of equal educational opportunities across the socio-economic spectrum. The work of this panel led to the formation of the Head Start program in the United States which involved the family and the community in efforts to intervene on the effects of child poverty.

Jerome Kagan

Jerome Kagan, born 1929, is an American psychologist. He grew up in New Jersey and got his doctorate from Yale University. The bulk of his research was conducted at Harvard University. He pioneered the field of child temperament. This work is described in greater detail in 11. Briefly, he was interested in personality traits, and the extent to which traits were consistent across the lifespan. He discovered that he could describe children as being more or less reactive, and that high or low reactivity in infancy led to the same level of reactivity in adulthood. Later he used brain imaging to discover parts of the brain that were associated with high reactivity. Relatedly, he became interested in the effects of daycare when the US federal government called for federally funded daycare. Kagan was very interested in development in the second year of life, and wanted to know whether daycare was adequate to development. He and his colleagues discovered that if an infant was in a high-quality daycare facility, there were no measureable negative when those children were compared to others who were raised in their homes by their mothers.

Walter Mischel

Walter Mischel was born in Vienna, Austria in 1930. He and his family were Jewish, and they moved to the United States when Mischel was 8 years old and Hitler’s Nazis occupied Vienna. Mischel’s training was in social psychology, and he has served the field as the president of the Associate for Psychological Science and the American Psychological Association and as editor of Psychological Review. His primary research contribution was to the field of personality psychology, which he essentially upended in 1968. The field had been founded on the premise that personality was a characteristic of an individual and could be observed as that individual moved from situation to situation. Mischel pointed out that that assumption just wasn’t true: even extroverts are quiet in a room full of high-status strangers. Mischel argued that although personality has measureable consequences with respect to behavior, the situation was actually the stronger factor in determining how a person would act and react.

An Evolutionary Perspective on Development

Children develop as a result of an intricate interaction between the environment and the developing child, and they do so as a result of developmental demands that recurred in the environment in which our ancestors evolved. You likely noticed that several of the earliest scientists studying developmental psychology, including Charles Darwin, G. Stanley Hall, and James Mark Baldwin, approached the field from the perspective of evolution by natural selection. Here we will consider developmental psychology through the lens of evolutionary psychology.

evolutionary psychology

An approach to the study of psychology that holds that being well informed about the process of evolution as well as the circumstances in which our ancestors lived during our evolutionary history will aid us in understanding the function and design of the human mind.

Evolutionary psychology is a productive perspective to consider and understand when working in the field of developmental psychology for a couple of reasons:

It promotes research that is consistent with what is known about evolution by natural selection.

It provides guidance in terms of hypothesis testing.

First, it behooves developmental psychologists to have an understanding of evolutionary psychology because proposals in the field of development need to be consistent with what is known about evolution. One example of a potential inconsistency is the idea that the infant’s mind is flexibly teachable without constraint and without biological imperatives, the blank slate idea. If simple learning mechanisms such as classical and operant conditioning were all a child had, anyone could teach the child to do anything, even if the learned behavior violated the child’s biological interests. This contradicts evolutionary theory, and the idea that psychological processes promote survival and reproduction.

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Theories about developmental psychology need to be consistent with other scientific knowledge, including natural selection.

A second way in which evolutionary theory contributes to developmental psychology is by providing guidance in terms of hypothesis testing. The complexity of a system (here, the developing child) determines the potential number of hypotheses that could possibly be tested. Human behavior, human development, and the human brain are very complex, so the number and scope of hypotheses that could be tested is unimaginable. There are clearly practical limits to testing as well, limits such as money, available participants, laboratory space, research assistants, writing time, and the scientist’s life span. Evolutionary theory, thankfully, narrows the hypothesis space significantly; one does not need to test hypotheses that are known to be inconsistent with evolutionary theory.

In general, an evolutionary perspective is important to the field of psychology, especially developmental psychology, because it frames our inquiry. It allows us to ask why the human mind is designed the way it is, what functions various psychological processes serve (e.g., face recognition, attachment, or depth perception), and how our unique human psychology was adaptive in the environment in which our ancestors evolved. The functional perspective that the evolutionary framework provides allows us to make sense of the interaction between a developing organism and its environment.

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An evolutionary perspective allows us to make sense of the interaction between a developing organism and its environment.

In order to understand how a psychological process works, we need to know what it was designed to do: its function. What adaptive problem in our ancestors’ hunter–gatherer environment was it solving? Vision? Language? Social cognition? Moral development? How is the mind designed so that a child can come to understand his or her physical, linguistic, and social world? With what learning mechanisms must the child be endowed? What parts of the environment inform these learning mechanisms? Evolutionary psychology lends a coherent framework for answering these questions.

Current Issues in Developmental Psychology

While reading this book and learning about developmental psychology, it may be useful to keep in mind some of the current issues that are discussed in the field. These are cases in which there may be two approaches or perspectives, continuity and discontinuity, plasticity and stability, and normative development or individual differences. However, they are not necessarily debates, because each perspective may be a valid perspective, depending upon which developing trait one is examining. Let’s look at these three issues.

CONTINUITY AND DISCONTINUITY

One current and continuing issue is the field of child development is the issue of continuity and discontinuity. If the development of a particular trait can be described in terms of continuity, this would mean that changes across time are quantitative. An older child is bigger, stronger, faster and smarter than a younger child. The older child seems smarter because she knows more words, has a greater memory span, and remembers more life experiences. These differences can all be described in quantitative terms.

continuity

Development that can be best described in quantitative terms, such as when a child gets bigger, stronger, faster or has a larger vocabulary.

discontinuity

Development that is best described in qualitative terms, such as cognitive changes characterized by a different kind of thinking or physiological and morphological changes that take place at puberty. The caterpillar changing into a butterfly is an illustrative example.

In contrast, some aspects of child development might be characterized by discontinuity. In this case, changes aren’t just quantitative but are also qualitative. The older child is smarter not just because she has more experiences, but also because she can use logical inference to apply knowledge to new situations, or can reason about abstract or hypothetical situations which the younger child cannot. The differences cannot be described quantitatively, as in she has more of a kind of knowledge or capacity, because the differences are more fundamental. She actually has a different kind of intelligence than her younger self.

To clarify, the example of the caterpillar and the butterfly is often offered. The butterfly is not just a bigger or even a more complex caterpillar, it is qualitatively different from the caterpillar. When an infant is born it changes from a being that lives in an aquatic environment to a being that breathes air, and from a being that gets its nutrition via its umbilical cord to a being that must eat and digest its own food. These are qualitative, not just quantitative differences. In addition, changes that take place during puberty, including reproductive capacity, cannot be explained just in quantitative terms.

Figure16ContinuityandDiscontinuity.jpg

Figure 1.6 Continuity and Discontinuity

The caterpillar and the butterfly are the same individual at different points in development. The developmental differences cannot be described just in quantitative terms (it is longer, e.g.). There are qualitative differences between the caterpillar and the butterfly. This illustrates discontinuity.

For developmental psychologists, the idea of discontinuity is exemplified by the theories of Jean Piaget. Piaget was a devoted stage theorist: he believed that as children developed, they moved from one stage into another and that such a move meant a fundamentally different way of understanding and thinking about the world. Piaget believed that children younger than 8 months of age do not have object permanence. When a toy they are playing with becomes occluded, they no longer know it is there. In contrast, after 8 months of age, an infant continues to have a representation of hidden objects, according to Piaget. The difference is qualitative, not quantitative, since it is a fundamental shift that cannot just be described as the child knowing more of something or having more of some cognitive capacity. Piaget also saw fundamental cognitive changes around puberty. Before the age of 12 or so, children were unable to reason about abstract objects, but were limited to reasoning about concrete objects that they could actually interact with. This changed fundamentally around the age of 12, according to Piaget, after which time children could apply reason to hypothetical situations.

false-belief task

An experimental task designed to test whether a child can perceive a character’s false belief and use that false belief to predict the character’s behavior.

the scale error

A phenomenon in which two-year-old children will try to interact with miniature toys as if they were not miniature.

Two more contemporary examples of discontinuity are the mastery of the false-belief task and the scale error. At the age of three years, most children cannot understand that another person could have a false belief, for example, that a marble is in a box when it is actually in the basket, nor that such a false belief could be used to predict and explain behavior: the misinformed person will search for the marble in the box when they should be looking in the basket. Most kids understand this by four years of age (Wimmer & Perner, 1983), a relatively fast qualitative change. The scale error is a phenomenon in which two-year-old children will try to interact with miniature toys as if they were not miniature. They will try to slide down a five-inch slide, or get into a car no bigger than their foot. Half a year later, they wouldn’t think of trying this (DeLoache, Uttal, & Rosengren, 2004). Again, this is an example of discontinuity, not a gradual change over time.

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Some aspects of child development are continuous and can be described in quantitative terms. Some aspects of child development are discontinuous and can only require a qualitative description.

PLASTICITY AND STABILITY

Another continuing issue in developmental psychology is describing the extent to which a trait or process is plastic, meaning designed to change in a functional way, or stable, meaning unlikely to change constructively. Plasticity in developmental psychology usually refers to functional change that happens by design as a result of factors in the environment or the child’s behavior, and also includes the reallocation of neural resources that takes place following injury. In contrast, stability refers to traits and characteristics that don’t change across the lifespan, or at least don’t change after some early point in development.

plasticity

Functional change that happens by design as a result of factors in the environment or the reallocation of neural resources that takes place following injury.

stability

describes traits that do not show plasticity. These traits are not expected to change, at least after some early point in development.

At issue are the questions of 1) whether various traits remain stable across the lifespan, or change across the lifespan and 2) among those traits that change over time, do they change in response to specific environmental cues or as a result of a maturational process? Don’t make the mistake of thinking that there will be one answer that applies to all development. Instead, the question can be asked for each trait that one wishes to consider: shyness, intelligence, gender identity, etc. For each trait of interest, the answer will be understood only as a result of empirical inquiry. For example, research suggests that attachment, once established in early childhood, is stable (Sroufe, Egeland, & Kreutzer, 1990), as is temperament, a child’s tendency to be irritable or react emotionally can change over time, specifically in response to warmth and acceptance on the part of their caregivers (Thomas & Chess, 1977).

You should expect that some traits would show greater plasticity while other traits should show stability. The circumstances in which people lived in our evolutionary history varied in unpredictable ways, so some traits will function better given some information about what kind of environment the child is living in. For example, in our evolutionary history, societies varied with respect to whether a father remained with his children and contributed resources as they grew up, and you’ll read in chapter 9 that the presence or absence of a father can affect a child emotional development, behavior, and even physiology. These traits show plasticity by design. Other traits are more stable, and are so by design. Some factors were more consistent across the environments of our ancestors, and thus didn’t affect the development of traits that were important to people across various environments. For example, the array of wavelength of light was fixed in our terrestrial environment: our ancestors saw different illumination at different times of day, but did not see light outside of a finite natural array. In the modern environment, our perception of color cannot be re-learned even if we are exposed to artificial light, as in a parking garage lit with fluorescent lighting. Thus, finding evidence that a particular trait is stable (or plastic) cannot be taken as evidence that stability (or plasticity) characterizes development generally.

Finally, realize that the extent to which a trait is plastic or stable can change during development. There are numerous examples of traits that are designed to respond to specific variables in the environment very early in infancy or childhood, but are less responsive, or unresponsive to environmental factors later in development. Examples are the configural perception of faces and the acquisition of grammatical rules. Look for others throughout this book.

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Some traits are designed to be stable, resilient to information in the environment. Some traits are designed to be plastic, responding to information in the environment. The extent to which a trait is plastic or stable can change during development.

NORMATIVE DEVELOPMENT AND INDIVIDUAL DIFFERENCES

One can describe two different approaches to developmental psychology: the normative approach and the individual differences approach. The normative approach is the study of development in which norms or averages are computed over a large population. In the normative approach, researchers are interested in describing the changes one typically sees in children, for example, the age at which children learn to walk, whether children sit before they crawl, or the age at which and order in which each language skill is acquired. Think of the way an anatomy book describes size and placement of organs on average, ignoring how these might vary between individuals. The individual differences approach, in contrast, focusses in measuring and characterizing the ways in which development and developmental outcomes differ among children, and also identifying factors that might predict these individual differences.

individual differences approach

An approach to development that focusses in characterizing the ways in which development differ among children, and identifying factors that predict these individual differences.

We mentioned earlier that G. Stanley Hall and Arnold Gesel were interested in the normative approach. They measured hundreds of children on both physical and psychological characteristics in order to calculate the average age at which various milestones were reached. Another example of the normative approach is language development in which developmental linguists strive to describe common linguistic patterns, such as learning a good number of nouns before the vocabulary of verbs expands, or babbling before producing meaningful speech. Another example of the normative approach is the core knowledge theory that you will read about in chapters 7 and 8, which posits that children typically develop