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Developmental Psychology






    Faculty Guide

    Developmental work is frequently organized chronologically, so one challenge that confronts students is how to think about developmental changes in a more holistic manner. One approach that we frequently take in our own lectures is to provide students with three general metaphors of developmental change: growth, differentiation, and orderly progression.


    One way to view developmental change is to see it from the perspective of growth. After all, one of the most striking features of human development is the sheer increase in size that occurs between conception and adulthood. At birth, the human brain is only 25% of its adult size. It attains 75% of its adult size two and a half years after birth, and 90% by age 5 (Tanner, 1990). Similarly, although newborns typically weigh less than 10 pounds, the average 5-year-old weighs 40 pounds and adults can weigh several hundred pounds. The growth perspective emphasizes the relatively smooth and continuous nature of these changes. As we develop, we get stronger as we add muscle, taller as our bones grow, and smarter as our brains reach their full size.


    Growth is not the only way to view change, however. Consider the 266 days of prenatal development from conception to birth. On the one hand, prenatal development can clearly be understood in terms of the growth perspective. In fact, it is the period in which physical growth is the most rapid. But it is also a stage in which complex structures arise out of more simple ones. For example, the many and varied tissues of the body have their origins in a single cell. As this cell divides, the resulting cells become more specialized. Some begin to form the nervous system, others the heart, and still others bones and hair. This process of moving from common simple structures to different complex structures is known as differentiation and it provides another perspective on developmental change. In our own lectures, we use two examples to help students understand differentiation. The first example concerns neural development. In the first few years of life, the number of synapses in the brain increases dramatically. (See the illustration of developmental changes in synaptic density.) Young children appear to form synaptic connections at the drop of a hat-an ability that may help explain the apparent ease with which they learn language and the plasticity of the infant brain. But as we age, synaptic connections become more specialized. Over time, neural pathways that are used get strengthened, while those that are not used disappear. In other words, our nervous system differentiates between useful connections and useless ones.

    The second example comes from motor development. Think about how an infant reaches for and holds something such as a wooden block. At 16 weeks, the infant cannot hold the block. At 20 weeks, she can grasp the block with her whole hand, but cannot move her thumb and fingers individually. Between 24 and 36 weeks, the thumb becomes differentiated from the fingers and she can pick things up by using her thumb against the four fingers as a whole. By 52 weeks, the thumb and each of the fingers have become fully differentiated and the child can pick the wooden block up using only her thumb and one finger. Although we often focus on the role that growth plays in development, differentiation is frequently the developmental challenge of the day. Riding bikes, playing instruments, learning to dive, and a host of other activities all depend on our ability to make increasingly complex and finely tuned movements.

    Orderly Progression

    A third way of understanding developmental change focuses on the orderliness and predictability of development. In the womb, cartilage tissue forms before bones. Similarly, young children creep before they crawl and stand before they walk. By focusing on the order and timing of developmental milestones, psychologists hope to better understand the genetic and environmental factors that influence physical, cognitive, and social development.



    Faculty Guide: Prenatal Risks
    Type of Activity: Interactive Table
    Learning Objective: Allow students to explore a variety of prenatal risk factors and teratogens.

    Faculty Note: In this interactive table, students can learn more about the effects of various teratogens on fetal development.


Motor Development

    Faculty Guide: Reflex Table
    Type of Activity: Interactive Table
    Learning Objective: Allow students to see examples of infant reflexes.

    Faculty Note: In this interactive table, students can explore a variety of infant reflexes.

    Faculty Guide The critical thinking questions here are intended to provoke discussion and reflection around the nature of reflexes. Students are often compelled to generate adaptive explanations for every reflex. In fact, the possible functions underlying many reflexes (e.g., the Moro reflex) are unclear and we should all be cautious when generating "as if" explanations for them.

    Faculty Guide: Motor Milestones
    Type of Activity: Interactive Table
    Learning Objective: Allow students to explore the sequence of infant milestones.

    Faculty Note: In this interactive table, students can explore a variety of motor milestones.

The Growing Brain

The Developing Senses



Taste and odor




Theories of Aging

    Faculty Guide

    Why we get old is a subject of some controversy. Gerontologists suggest that there are several processes that contribute to the physical decline observed in aging:

    • Wear and tear. We simply "wear out" over time from physical activity and interaction with our environment. Exposure to adverse environmental factors such as radiation and chemical toxins are destructive to body tissues over the long term. The mechanical strains on our organs and "moving parts" cause them to deteriorate. Although our bodies can repair themselves to some degree, the repair work eventually fails to keep pace with the deterioration.

    • Cellular garbage. Inside our cells, toxins and waste products accumulate over time, interfering with the ability of the cells to function and repair themselves. One candidate is the formation of free radicals, molecules that are extremely chemically reactive and are thus prone to bond with vital structures in the interior of the cell. Since free radicals are by-products of natural reactions in the body and are also abundant in the environment, they are difficult to avoid.

    • Endocrine clocks. After peaking at about age 20, levels of sex hormones, growth hormones, and other chemical messengers begin to decrease steadily. According to some gerontologists, many of the physical symptoms of aging may be traced to decreased functioning in various glands of the endocrine system. The immune system that protects us from disease declines as well; the thymus gland, which is involved in the production of T-cells for the immune system, decreases in size by 90% or more by age 50.

    • Genes. We may be genetically programmed to age and die. For example, it may be that we have a biological "clock" in our genetic code that limits the lifespan of our cells. Researchers such as Leonard Hayflick (1977, 1996) have discovered that human cells typically stop reproducing themselves after about 50 cell divisions. Segments of DNA known as telomeres become shorter every time a cell divides, counting down to a point at which the cell can no longer replicate itself. Without the ability to divide and reproduce, the cells of the body die off and the tissues of the body begin to degrade.

    As fundamental mechanisms that can produce age-related changes in all humans, these factors might be described as theories of primary aging. In addition to the forces that drive primary aging, gerontologists also enumerate many causes of so-called secondary aging, or the contributions of disease, environment, and lifestyle to our physical deterioration. As we age, we are increasingly likely to be debilitated by heart disease, cancers, the health consequences of poor nutrition, and degenerative disorders such as Alzheimer's Disease or Parkinson's Disease.

The Aging Brain


    Faculty Guide

    Alzheimer's Disease is a topic that likely has personal relevance to many students. Alzheimer's Disease strikes first in the areas of the brain involved in memory, such as the hippocampus (Jack et al., 1999); the initial symptoms are often forgetfulness and the loss of short-term memories. Eventually, victims may fail to recognize close family members or even their own image in a mirror. In the final stages of the illness, sufferers are unable to care for themselves or perform many simple activities of daily living.

    The causes of Alzheimer's Disease are only now being understood. There are probably genetic factors in some cases (Clark & Goate, 1993). Individuals who inherit genes from both parents for a certain type of blood plasma lipoprotein (ApoE4) are 8 times as likely to get Alzheimer's Disease as those who do not (Marx, 1998). Other causes are still being investigated, such as exposure to strong electromagnetic fields, metals in the environment, and unknown disease agents such as viruses.

The Aging Senses



Taste and odor




Assimilation and Accommodation

    Faculty Guide: Assimilation Classification
    Type of Activity: Interactive Reinforcement
    Learning Objective: Reinforce the distinction between assimilation and accommodation.

    Faculty Note: In this activity, students are presented with behaviors that they must categorize as either reflecting assimilation or accommodation.

Piaget's Stages of Cognitive Development

Sensorimotor stage

Preoperational stage

    Faculty Guide: Egocentrism Classification
    Type of Activity: Exploration
    Learning Objective: Gain a better understanding of the methods used to study egocentrism.

    Faculty Note: In this activity, students are presented with Piaget's classic mountain problem and the responses given by egocentric and non-egocentric children.

Concrete operations

Formal operations

    Faculty Guide: Stages of Cognitive Development
    Type of Activity: Interactive Reinforcement
    Learning Objective: To reinforce learning of the characteristics associated with each of Piaget's stages (sensorimotor, preoperational, concrete operations, and formal operations).

    Faculty Note: In this activity, students use "drag and drop" to match Piaget's stages with key attainments and characteristics of the stages.

Piaget's Stages Reconsidered

    Faculty Guide: Baby Theater
    Type of Activity: Movie
    Learning Objective: Allow students to see examples of the methods developmental psychologists use to explore infant cognition.

    Faculty Note: One of the challenges that confronts developmental psychologists involves how to measure developmental progress among very young children. In this activity, students read about preference procedures and habituation procedures and then watch two movies that show how these procedures can be used to probe infant cognition.

Was Piaget Wrong?


Adolescent Development

Moral Reasoning

    Faculty Guide: Moral Development
    Type of Activity: Exploration
    Learning Objective: Further explore Kohlberg's moral framework.

    Description: After briefly reviewing Kohlberg's model, students have the opportunity to see video vignettes that present a variety of moral dilemmas. After watching each vignette, the students are able to choose the response that they feel is most appropriate from a list of common responses. They then get feedback concerning how their response fits into Kohlberg's framework.

Kohlberg's model

Criticisms of Kohlberg's model


    Faculty Guide: Fluid versus Crystallized Intelligence
    Type of Activity: Interactive Reinforcement
    Learning Objective: To reinforce the distinction between fluid and crystallized intelligence.

    Faculty Note: In this drag and drop matching activity, students are presented with behaviors that they must categorize as reflecting either fluid or crystallized intelligence.



Studying Attachment

Implications for Later Development

    Faculty Guide: Attachment Style Movie
    Type of Activity: Movie
    Learning Objective: To vividly illustrate the behaviors associated with the major attachment styles (secure, avoidant, and resistant/ambivalent).

    Faculty Note: In these movies, students observe infants in the Strange Situation paradigm. Infants who are securely attached are distressed when the mother leaves, but quickly calm down upon her return. Infants who are avoidant ignore her when she leaves and continue to ignore her after her return. Infants who are resistant/ambivalent are upset when the mother leaves and remain distressed after her return.

Developing Attachment


    Faculty Guide: Who Am I?
    Type of Activity: Simulation
    Learning Objective: Explore the roles that similarity and uniqueness play in the self-concept.

    Faculty Note: This activity is based on McGuire's "Who Am I Test." In the activity, students are asked to provide answers to the question "Who am I?" They are then shown the types of responses that emerge from children of different ages. Two things typically emerge. First, younger children tend to give concrete descriptions (e.g., I'm tall, I wear red shoes, etc.), while older children give more abstract description (e.g., I'm smart, I'm old-fashioned). Second, people tend to describe themselves in terms of the features that make them unique (e.g., I'm the only girl in a family of five, I'm left-handed), rather than in terms of the features that make them similar to others (e.g., a citizen of country X). This activity is closely related to the main text that follows, where it is noted that the tendency to focus on unique features may be limited to Western cultures.

Describing the Self

Social Changes in Adolescence

Social Development in Adulthood


Trust vs. Mistrust

Autonomy vs. Doubt

Initiative vs. Guilt

Industry vs. Inferiority

Identity vs. Role Confusion

Intimacy vs. Isolation

Generativity vs. Stagnation

Integrity vs. Despair

    Faculty Guide: Erikson's Stages
    Type of Activity: Interactive Reinforcement
    Learning Objective: To reinforce learning the characteristics associated with each of Erikson's stages (Trust vs. Mistrust, Autonomy vs. Doubt, Initiative vs. Guilt, Industry vs. Inferiority, Identity vs. Role Confusion, Intimacy vs. Isolation, Generativity vs. Stagnation, and Integrity vs. Despair).

    Faculty Note: This activity comes in two parts. In the first part, students use "drag and drop" to match Erikson's stages with the key achievement that marks transition to the next stage. In the second part, they must organize the stages in the chronologically correct order.

Erikson's Theory in Review