Chapter 8: Lifespan Development of Human Potential

Child Development


Whether a child grows up in the rainforest or a city, its thumb, tongue, and cortex will facilitate its adapting to its environment. That combination of physical characteristics has enabled us to survive as a species under a vast range of human conditions. During the first year, infants learn to use the forefinger and thumb to form the precision grip, permitting the grasping and manipulation of objects. As soon as children are sitting up they often enjoy solitary play. In the rainforest, children are given sticks and stones to manipulate. Favored toys for children growing up in contemporary homes include blocks of different shapes. Gradually, infants learn the futility of trying to put round blocks in square holes. Besides shapes, blocks are also excellent devices for teaching colors and even letters of the alphabet. As they develop, children may experiment by piling blocks on top of each other and creating different structures. Blocks can even eventually help children learn the “ABC”s.

Maturation refers to those developmental processes that occur as the result of aging. Your child will grow and its body proportions will change with age. Its head will become proportionally smaller and its limbs proportionally larger. As different parts of the body develop, new behaviors become possible.

Fundamental to adaptation and independence is walking on one’s own. Whether growing up in the rainforest or a large city, the child must sit up before crawling and stand before walking (see video). As a concerned parent, you will be interested in assisting your child achieve their continually increasing potential. The figure indicates the significant ranges children display in the ages at which they first demonstrate each behavior. Keep such individual differences in mind so that you do not become overly concerned if your infant appears a little slow in acquiring their first baby steps or other essential skills.


Watch the following video of an infant gradually learning to walk:

In addition to walking, there are other survival-related skills children must acquire during early infancy. They must learn to use their hands to eat, reach for, grasp, and manipulate objects. Gradually, children must learn to communicate with their caregivers using gestures and eventually language. Favorite games of infants include pointing to the parts of the face and peek-a-boo.

Humans are social animals born dependent on others; the course of their development will be significantly influenced by their interpersonal skills. Children must learn to interact with other family members as well as strangers, including other children.

The noted Russian psychologist, Lev Vygotsky (1962, 1978), described child development as the transition from socially shared activities to internalized processes. Through interactions with parents and other adults within a community, the child acquires speech. The child speaks out loud during the language acquisition phase. Eventually, speech is internalized (i.e., becomes silent) and serves as the basis for thought and action. Happy birthday! Your pretend baby will soon be celebrating her/his first birthday. You are eager to help your child along its way to achieving their potential. You would like her/him to walk and come to you when requested to do so. Teaching your child is essentially a problem-solving exercise as described in the previous chapter. How does your child behave now? How would you like your cild to behave in the future? What do you need to do to develop this behavior? Vygotsky proposed that a “zone of proximal development” existed, whereby teaching should only commence when it is certain the child is ready. We will assume your child is ready once standing without support and responding appropriately to a few words.

Vygotsky also introduced the term “scaffolding” to refer to effective adult support when teaching a child. At one year of age, you will not be able to rely entirely on language to teach walking. In Chapter 5, we described the shaping, prompting, and fading teaching techniques. Shaping is a scaffolding technique that continuously relies upon Vygotsky’s concept of a zone of proximal development. You start with a behavior already in the child’s repertoire and proceed only when the child is ready for the next step. Prompting and fading are also scaffolding techniques that can facilitate and speed up the learning process. You could teach your child to walk using shaping, prompting, and fading similar to the process described in Chapter 5 to train a dog to roll over. Unlike teaching a dog, however, it is not necessary (nor a good idea) to use food as a reinforcer. Recalling the distinction between extrinsic and intrinsic rewards from the previous chapter, your child will probably find covering ground and moving faster intrinsically motivating. You can establish feedback and praise as conditioned reinforcers by pairing success with words describing the accomplishment as well as words of affection. Remember the control learning ABC’s when starting out. When standing, say “Come to me” (an antecedent) while softly holding your child and trying to get her/him to take an initial step (a behavior). As the child moves, you could say “You are walking. What a big boy/girl” (a consequence). Once the child starts moving slightly when you say “Come to me”, you can release your grip a little. This would proceed until the child takes an initial step without your assistance. Now you could request “Come to me” while kneeling or standing a little further away and holding out your arms. You can close your arms and hug the child when he/she reaches you. By proceeding “step by step” in this fashion, your child will eventually come to you from any location upon request. Once walking, you could use the same procedures to request that the child bring you different objects. In addition to being a fun bonding and vocabulary development exercise, this process includes all sorts of benefits. For example, you can teach, “Please bring me my slippers, newspaper, TV remote”, etc. I don’t suggest trying “Bring me my coffee” for a while though.

Your child’s motor and cognitive abilities will continue to improve and expand during the second year. Imitation of the behaviors of other adults and older children will become more frequent. At the end of the first year, you will probably try to teach your child to attend to you and stop what they are doing when you say the word “No.” You may recall that this has the benefit of reducing the need to use physical punishment. Unfortunately, this may be an instance of “be careful what you wish for.” Teaching the word “no” may seem like a great success at the time, but eventually prove to be a two-edged sword. Don’t be surprised if, as your child starts the “terrible twos”, she/he says “No” every time you request something. Probably toward the end of your child’s second year, unlike parents in the rainforest, you and your significant other will try to teach control of a natural biological function; excretion of waste materials in liquid and solid form. In the rainforest, the Nukak child, who similar to your child, learned to walk during the first year, will be shown where to walk (or move a little faster when necessary) when “nature calls.” In your home, and as preparation for visiting the homes of others as well as nursery or pre-school, you will show your child where and how to “go potty.” Most likely, your child will say “No!” Once again, you may be wondering how to proceed with this latest exercise in problem solving. Vygotsky’s concepts again provide helpful guidance. You first need to determine whether your child is ready for toilet training (i.e., the zone of proximal development) and then determine the most appropriate teaching procedures (i.e., scaffolding).

There are many recommended “recipes” for toilet training available on Google and YouTube. How do you decide which to implement? Fortunately, there are empirically based assessment and teaching strategies. In Chapter 2, we saw that conducting an experiment in which an independent variable is manipulated is the only way to determine cause and effect. In this instance, we need to search the research literature to see if there is an experiment demonstrating the effectiveness of a toilet training procedure. Nathan Azrin was the 1975 recipient of the American Psychological Association Award for Distinguished Contributions for Applications in Psychology. What is startling and impressive about Azrin’s body of research is the consistent experimental demonstration of success of his intervention procedures with some of the most serious and intractable behavioral problems. These include his classic token economy procedures with chronic adult schizophrenics (Ayllon and Azrin, 1968), community reinforcement procedures with problem alcohol abusers (Hunt and Azrin, 1973), and social reinforcement procedures for individuals experiencing long-standing difficulties finding a job (Jones and Azrin, 1973). In addition, Azrin wrote the best-selling (and still available) Toilet Training in Less than a Day (Azrin and Foxx, 1974) based on prior successful research results (Azrin & Foxx, 1971; Foxx and Azrin, 1973).

Unlike walking, toilet training involves establishing a lengthy sequence of unrelated behaviors. It would be a time-consuming and painstaking task requiring extreme patience and skill to teach this sequence using the shaping, prompting, and fading procedures. Azrin and Foxx (1974) suggest waiting until your child is at least 20 months old before assessing whether she/he is ready to begin toilet training (i.e., has reached the zone of proximal development). Prior to then, it is unlikely that your child will have acquired the observational learning and language skills necessary to use indirect learning procedures. Before beginning you should insure your child is able to sit up, walk, imitate, know the names of and point to different body parts, remove and replace underwear, follow simple instructions, sense the need to go to the bathroom, and stay dry for at least two hours (Azrin and Foxx, 1974, 43-45).

Once these pre-requisite skills have been acquired, you are ready to proceed. Their process is based on the premise that the best way to learn something is to try to teach it to someone else. This will require having a doll which appears to wet. In this way your child can “teach dolly to go potty.” You start by pretending to give the doll a drink and telling your child that the doll has to go to the bathroom. Your child should then be shown how to remove the doll’s diaper, seat it on the potty, wait for it to “urinate” and then praise the doll for going to the potty (see Azrin and Foxx, 1974, 58-85 for detailed instructions).

Language and the Human Condition

Toilet training is perhaps the earliest example of the advantage of using language to teach a child. The acquisition of speech enables the transition to Piaget’s preoperational stage of cognitive development. The early structuralists considered sensations, images, and emotions to be the basic elements comprising conscious experience. The child is now able to symbolically represent these elements (i.e., its internal and external environment) with words. Vygotsky emphasizes the transition from talking out loud to talking to oneself. We use words to represent objects (nouns), actions (verbs), characteristics of objects and actions (adjectives and adverbs), and people (pronouns). Much of our thinking, including planning and problem-solving, consists of covert speech. Little by little, over the course of our lives, we describe our concepts and schemas with words as we develop elaborate narratives for understanding ourselves and our worlds.

All known human cultures speak. As quoted by Skinner (1986) in Chapter 6, it is perhaps the part of our genetic potential most responsible for our achievements as a species. Infants typically show signs of understanding speech at about six months but do not start speaking before one year of age. We described the importance of vocabulary size to success in school in Chapter 6 (Anderson and Freebody, 1986). Hart and Risley (2004) refer to these findings as “The Early Catastrophe: The 30 Million Word Gap by Age 3” (see video below). It has been estimated that disadvantaged children enter school with a vocabulary of 5,000 words in comparison to their more advantaged peers who average 20,000 (Moats, 1999). Research has shown a strong relationship between the vocabulary of first-graders and their subsequent reading comprehension scores (Cunningham & Stanovich, 1997; Scarborough, 2001). Findings indicate that Pre-K and kindergarten intervention efforts designed to improve vocabulary have been successful for middle- and upper-income at-risk children, but unfortunately, not thus far for lower-income children (Marulis & Neuman, 2010).


Watch the following video describing the 30-million word gap:

Preparing Children to Be Hunter-Gatherers

The portion of the Amazonian rain forest inhabited by the Nukak, consisting almost entirely of marshes and wetlands, does not support a permanent lifestyle based upon domestication of plants and animals (Politis, 2007). There are, however, abundant edible non-domesticated plant, fruit, and vegetable species and some edible animals (e.g., several species of monkeys, peccaries, tortoises, birds, ducks, and fish). The Nukak are one of the few remaining cultures continuing to practice the nomadic hunter/gatherer lifestyle characteristic of the earliest members of our species. They travel in bands comprised of approximately five nuclear families with a median of 20-30 individuals. Temporary shelters designed for stays of about four days are crafted from posts, tree branches, and leaves to form a camp. Furnishings include hammocks for sleeping and a hearth for cooking.

The Nukak, living day to day, have maintained a similar lifestyle for more than 10,000 years. They lack familiarity with government, property, or money. The Nukak do not have a concept of the future and their past history is limited to a few generations. In order to survive under very challenging conditions, the Nukak had to acquire the knowledge and skills to protect themselves from the elements and predators. They had to learn to forage and prepare a non-poisonous, nutritionally adequate diet.

Daily excursions from the camp are almost always led by an adult male, and many are limited to males. Most of the activities are related to hunting, fishing, and collecting foods (fruits, vegetables, honey, etc.). These trips also involve collecting resources such as cane for blowpipes, leaves for roofs, bark and vines for cords. Since their shelters have such low population densities, trips can involve searches for potential mates among other bands. Females often take part in local foraging trips, but most of their time is spent near the shelters caring for young children and preparing food. Time is frequently taken out during the day for men and women to pass on survival skills from generation to generation.  Having to dedicate most of the day to survival needs and child care leaves precious little time for the Nukak to address the interpersonal and self-actualization needs higher on Maslow’s pyramid.

The Nukak have faced the same environmental demands and parents have transmitted the same survival skills from generation to generation for millennia. The Nukak essentially have two stages of development, childhood and adulthood. Piaget’s first two stages of cognitive development apply to Nukak children as well as those growing up in cities. They will start to speak at approximately the same age and their parents will take advantage of speech when teaching them. Nukak children’s toys usually consist of scaled down versions of survival tools. They participate in foraging, hunting, and food preparation as soon as they are physically able.

Preparing Children for School

The Nukak’s childhood contrasts with the extensive schooling required to create a common knowledge base and prepare children in technologically advanced cultures for ever-changing vocations. Many countries have compulsory primary and secondary education in order to address these goals. Thus, in addition to teaching a culture’s code of conduct, parents in these countries need to prepare their children to attend school.

Time is flying by and your pretend child is about to celebrate her/his third birthday. Congratulations, it is the end of the terrible twos! It is at this time that the life path for children growing up in the rainforest and city will diverge significantly to adapt to their different environmental demands. In order to adapt to the rainforest, the Nukak child will be taught gender appropriate hunter-gatherer skills. During the next two years you will help your child acquire many concepts and skills which are prerequisites for success in school. You will teach the names of colors, letters of the alphabet, numbers, and telling time. Gradually, his/her vocabulary will expand, sentences become more grammatical, use of imagination in telling stories and engaging in fantasy play increase, and interactions with other children become more cooperative. Conversations will increase in length and become more adult like in being targeted to the listener.

In 1998, the International Reading Association (IRA) and the National Association for the Education of Young Children (NAEYC) issued a research-based position statement regarding the teaching of reading and writing. Included in their statement were recommendations regarding what children, caretakers, and teachers can do at different ages to teach these skills. During the preschool years, it was recommended that parents and family members do the following:

  • Talk with children, engage them in conversation, give names of things, show interest in what a child says
  • Read and reread stories with predictable texts to children
  • Encourage children to recount experiences and describe ideas and events that are important to them
  • Visit the library regularly
  • Provide opportunities for children to draw and print, using markers, crayons, and pencils (IRA and NAEYC, 1998)

School represents a different “world” for children with its own set of adaptive requirements. Parents play an important role in preparing their children for school. The authoritative style characterized by high demandingness and high responsiveness has been shown to result in better school performance than the authoritarian style (Pratt, Green, MacVicar, & Bountrogianni, 1992; Hokoda & Fincham, 1995). In school, teachers, rather than parents, are the ones establishing standards and administering consequences. The dimensions of demandingness and responsiveness may be applied to teaching as well as parenting styles. Teachers may hold high or low standards for their students. They may be personable and warm in their classroom interactions or distant and detached. As with parenting, authoritative teaching styles result in better academic and social performance than authoritarian styles (Walker, 2008).

The School Years

Congratulations! Your pretend child is off to kindergarten. For perhaps the first time in your child’s life, you and she/he will endure the emotional process of extended separation. You and your child’s teacher will hopefully engage in a collaborative process designed to identify zones of proximal development and implement appropriate scaffolding techniques. During kindergarten the IRA and NAEYC recommend that parents and family members:

  • Daily read and reread narrative and informational stories to children
  • Encourage children’s attempts at reading and writing
  • Allow children to participate in activities that involve writing and reading (for example cooking, making grocery lists)
  • Play games that involve specific directions (such as Simon says”)
  • Have conversations with children during mealtimes and throughout the day

Your pretend child is getting older. Nature and nurture are interacting to result in a unique individual with likes/ dislikes, interests/ disinterests, ways of coping, and range of emotions. Some changes are obviously continuous. Your child is gradually getting taller (although there will be a spurt later on). We have seen that even a characteristic so obviously influenced by genes as height, is impacted upon by environmental factors such as nutrition and illness. The child’s vocabulary is similarly undergoing incremental growth and we start to observe apparent changes in reasoning, approaching and solving problems, and communicating with you and others.

In Chapter 7, we saw how the ability of chimpanzees to solve two-choice visual discrimination problems improved gradually over the course of 300 problems. At the end, the chimp appeared to solve the problems in a qualitatively different manner. Rather than observing gradual improvement across the first six trials of each new problem, the chimp would jump from chance to perfect performance on the second trial (Harlow, 1949). One might conclude, it transitioned from an “incremental learning stage” to a “hypothesis-testing stage” of development. The name of the stage is descriptive of the performance, not explanatory. The explanation lies in the history of exposure to examples of the same type of problem. Although heredity and environment interact gradually and incrementally, sometimes the behavioral effect appears to constitute a qualitative change in the individual. The ability to comprehend language and speak result from physical development of the infant’s brain and speech organs, improved ability to imitate, and continual exposure to vocalizations.



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Psychology by Jeffrey C. Levy is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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