Chapter 8: Lifespan Development of Human Potential

Theories of Development

Piaget’s Stage Theory of Cognitive Development[

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” 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.

Jean Piaget, a Swiss psychologist, proposed an influential theory of cognitive development from birth through adulthood (Piaget, 1928; 1952; 1962; Piaget & Inhelder, 1973). Piaget was an example of a stage theorist. Stage theory describes human development as a fixed sequence of capabilities resulting in qualitatively different ways of responding to the world. Piaget describes cognitive development as the continual modification (i.e., accommodation ) of schemas based on the incorporation (i.e., assimilation ) of new knowledge.  Piaget applied the overarching principles of assimilation, accommodation, and schema development to integrate the cumulative interactive effects of heredity and experience as the child ages and advances through the different stages.

The sensorimotor and pre-operational stages last from infancy through preschool and the early grades. During the sensorimotor stage (from approximately birth to two years) the child is preverbal, learning the relationships between sensory (e.g., visual and auditory) stimuli and movement. During the pre-operational stage , the child is able to use language to acquire skills and knowledge.  Interacting with a child that speaks is fundamentally different than interacting with a non-verbal child. Piaget’s distinction between non-verbal (sensorimotor) and verbal (pre-operational) stages seems appropriate and important. A child is able to learn in a qualitatively different way once acquiring speech.  We need to be careful, however, in how we interpret the meaning of a stage of development. It is one thing to describe the child as behaving as though being in a particular stage and a very different thing to offer the stage as an explanation for behavior. You might recognize this as another example of a pseudo-explanation. Why does the child speak? Because she/he is in the pre-operational stage. How do you know she/he is in the pre-operational stage? Because she/he speaks.

The newborn is able to sense the environment and emit a variety of responses. Whether in the rainforest or at home, as the newborn turns its head it will observe that some objects are stationary and others move. Some of the moving objects make sounds and others do not. Some of the objects feel soft and cuddly whereas others are hard. One of the soft moving objects makes sounds and sometimes approaches and holds the infant while placing its lips near something soft. This soft object can be sucked, resulting in the availability of a substance which can be tasted and smelled. The newborn’s initial schemas will most likely center around these external environmental stimuli and the internal sensations associated with basic survival drives such as eating and terminating discomfort. Eventually, some objects will be incorporated within a schema (e.g., objects that do not move), others might require modification of a schema (e.g., objects that can be moved and placed in the newborn’s tiny fingers), while others may require creation of an additional schema (e.g., round objects that move if simply touched). Gradually, concepts will be acquired (e.g., flat objects, round objects, heavy objects, light objects, soft moving objects that make noise and provide food, moving objects that make noise and bathe the infant, other similar looking moving objects that are usually present, other similar looking moving objects that are sometimes present, different looking moving objects that make different sounds and are usually present, etc.).

As the infant’s senses and motor abilities improve during the sensorimotor stage, it starts manipulating the environment and gradually acquires the ability to predict and control what happens. Piaget describes a three-stage sequence of circular reactions (i.e., repetitious behavior) taking place during this first, sensorimotor period of development.  Primary circular reactions appear to be repetition of a behavior for its own sake, or perhaps the resultant sensations. Secondary circular reactions consist of the types of behavior demonstrated by Rovee-Colier where the infant repeats an act resulting in a specific environmental effect. Tertiary circular reactions appear to involve attempts by the infant to produce the same environmental effect with different responses. Such attempts typically start to appear at about eight months of age and constitute the first examples of “experimentation.”

In addition to learning that she/he exists as an independent object, Piaget felt that an important concept acquired in the sensorimotor period is object permanence . Initially, children act as though once objects disappear from view they no longer exist; that is, “out of sight, out of mind.” Evidence suggests that children as young as 3-1/2 months old behave as though they understand object permanence. This is inferred from the fact that they look longer at events which turn out different than they apparently anticipated (Baillargeon & DeVos, 1991). For example, it has been shown that young infants will gaze longer at an impossible event (e.g., a toy train appearing to move through a block rather than hitting it (see below) than at a possible event.


Watch the following video showing Baillargeon’s test for object permanence:

Piaget suggested that, at about seven years of age, children advance from the pre-operational stage to the stage of concrete operations . It is at this time that the child appears to understand how certain operations can transform the appearance of objects but not their fundamental characteristics. As shown in the previous video, Piaget developed ingenious tasks for assessing this ability through the demonstration of conservation of number, mass, and liquid volume .  Here is another video showing developmental changes in children’s understanding of conservation of number, length and volume.

The following video describes Piaget’s sequence of four distinct stages of cognitive development.


Watch the following video of Piaget’s stages of cognitive development:

If you first show a pre-operational child the two rows of five coins lined up so they match (a) and then spread out one of the rows (b) while they are watching , the longer row will be described as having more. They do not yet understand that the operation of moving the objects does not change the quantity. Similarly, a pre-operational child is likely to say that if one of two same-sized balls of clay is rolled into a sausage, it is now larger; or if one of two same-sized glasses containing the same amount of water is poured into a narrower but taller glass, it now has more. Children responding correctly are considered to have advanced to the stage of concrete operations. They understand how the concept of reversibility applies to the operations performed on the row of coins, clay, and liquid. The coins can be moved back to their original positions, the clay sausage rolled back into a ball, and the water poured back into the original glass.

To demonstrate another difference between a pre-operational child and one in the concrete operations stage, Piaget developed a task to determine the ability to perceive someone else’s perspective, as shown in the video.  The child was shown a realistic model of a scene including a mountain, toy animals, and plants. The young pre-operational boy only sees the scene from his own perspective. The older boy in the stage of concrete operations is able to imagine the scene from the adult’s position. Piaget and others describe the young boy’s behavior as reflecting egocentrism.

Piaget’s stages describe a progression in the child’s ability to use and manipulate symbols (i.e., to “think”). During the pre-operational stage the child is able to use words to symbolically represent objects and events. During the sensorimotor stage the child is restricted to symbols representing the structuralist’s three basic elements of consciousness; sensations, images, and emotions.

You might be wondering what it means to symbolically represent objects and events in the absence of language. In classic research, Walter Hunter (2013), a student of Harvey Carr’s (one of the early functionalists), tested to see whether his daughter and different animals could symbolically represent the location of an object. The procedure involved a small maze where a light could go on behind one of three “doorways.” If the subject went through the lit doorway, there was food present. There was no food behind the other doorways. This is a simple task for most animals to learn. However, if the light was turned on and then off, a rat could only go to the correct doorway if it oriented itself while the light was still on. Then, it would literally “follow its nose.” If the rat was spun around and released after the light went off, it performed at chance. Raccoons, chimpanzees, and Hunter’s daughter, went to the correct location even though there was no longer an external cue (i.e., light) to guide them. Hunter inferred from this behavior, that these subjects must have symbolically stored information concerning the prior location of the light in order to go to the correct doorway. This ability would have important survival value. For example, if an animal that is not hungry noticed food in a particular location, it would increase the likelihood of survival if it could return to that location when hungry. In addition, this test permitted Hunter to know when he needed to keep his eye on the family cookie jar!

During the concrete operations stage, the child is not only able to symbolically represent objects and events, but is also able to imagine manipulating concrete (i.e., observable) objects and events. The child can imagine moving the coins, squeezing the clay, pouring liquid from one container into another, or moving around the scene of the mountain. Piaget believed his final stage, formal operations , was reached between 12 and 15 years of age (Piaget, 1972; Piaget & Inhelder, 1958). The more adult-like teenager is able to imagine manipulating abstract concepts. For example, without looking at actual objects, an adolescent could be asked “If A is larger than B and B is larger than C, must A be larger than C?” She/he can imagine multiple examples fulfilling the requirements of the statements and arrive at the correct answer. The ability to mentally manipulate abstractions underlies logical thinking, scientific hypothesis testing, and every day problem-solving. The teenager can now execute all the stages of the problem-solving process symbolically: consider how things are, consider how she/he would like them to be, list optional solutions, evaluate the short- and long-term consequences of the different strategies, and arrive at a potential solution.

Piaget’s theory of cognitive development has been extremely influential and generated an enormous amount of empirical research. Piaget, himself, was a gifted child with an early interest in biology. He published several articles by the age of 15! A little known fact is that soon after receiving his doctorate, Piaget moved to Paris and worked with Alfred Binet in constructing items for his seminal school readiness test. Piaget’s stage theory was influenced by the distinct types of errors children of different ages made to certain questions on this test. From these errors, Piaget inferred qualitatively different cognitive styles (pre-operational, concrete operations, and formal operations). Based on his early interests and later work, it is not surprising that the tasks Piaget developed to study cognitive development are oriented toward scientific thinking or that performance on these tasks correlates with school readiness and intelligence tests (Humphreys & Parsons, 1979).

Piaget has been criticized for basing his theory on the observation of a very small non-representative sample of individuals; his three precocious children and the children of highly-educated professionals. Research conducted with more representative samples has generally supported the sequence Piaget described in the ability to solve different types of problems. However, there is considerable variability in the ages at which different children demonstrate the characteristic behavior patterns of the different stages. For example, as previously cited, pre-verbal (i.e., sensorimotor stage) children can demonstrate object permanence (Baillargeon & DeVos, 1991). At the other end of Piaget’s developmental sequence, adults frequently lack or are inconsistent in their usage of formal operational thinking. Piaget (1972) himself recognized this inconsistency. He suggested that experiential differences with different domains of skills (e.g., physics, mathematics, philosophy, etc.) could result in concrete operational type performance in some situations and formal operational performance in others. In the next chapter, we will see that this same pattern of inconsistent performance across situations applies to other human personality characteristics in addition to cognitive style. Some have argued that Piaget fails to appreciate the underlying role of basic cognitive processes (e.g., short-term memory, processing speed, etc.) in movement from stage to stage as well as individual differences (Demetriou & Raftopoulos, 1999; Demetriou, Mouyi, & Spanoudis, 2010). It has been demonstrated that science training improves performance on the Piagetian tasks (Lawson, 1985). Such training effects suggest that movement through the stages is more reliant upon experience than Piaget implies.

Moral Development

Children are completely egoistic; they feel their needs intensely and strive ruthlessly to satisfy them.

It is impossible to overlook the extent to which civilization is built upon a renunciation of instinct.

The first requisite of civilization is that of justice.

Sigmund Freud


Piaget’s interests extended beyond the development of knowledge and skills related to nature (i.e., scientific thinking). He was also deeply interested in the individual’s development of a moral code (Piaget, 1932). Not surprisingly, Piaget believed that the cognitive changes occurring as the child and teenager advanced through the developmental stages influenced their moral thinking as well as their understanding of nature. During the pre-verbal sensorimotor stage, direct learning principles account for changes in behavior. The child increases the frequency of behaviors resulting in appetitive (i.e., “feel good”) or reducing aversive (i.e., “feel bad”) outcomes and suppresses behaviors resulting in aversive or the loss of appetitive outcomes. As the child initially acquires language during the preoperational stage, rules are imposed by adults (primarily parents and caregivers) and understood in a literal, inflexible way. Later, the child gradually interacts with other children, makes friends, and goes to school. The parents’ influence is diluted by the direct and indirect (i.e., observational and verbal) contingencies experienced with different adults (e.g., teachers, members of the clergy, etc.) and their peers. As the child becomes less egocentric during the stage of concrete operations, he/she is able to appreciate the perspectives of others and recognize the possibility and need to cooperate by negotiating rules of conduct. Once attaining the stage of formal operations, teenagers and adults are able to appreciate and consider more subtle and abstract aspects of interpersonal and moral issues (e.g., the benefits and need for fairness, justice, responsibility, etc.).

Kohlberg’s Stage Model of Moral Development

Lawrence Kohlberg (1976) developed a very influential stage model of moral development based on Piaget’s stage model of cognitive development (see Figure 8.11). He distinguished between three different levels (“styles”) of reasoning : pre-conventional, conventional, and post-conventional, each sub-divided for a total of six stages. Pre-conventional morality is based upon extrinsic rewards and punishers. At first, during Piaget’s sensorimotor period, the child is only sensitive to extrinsic rewards and punishers. Once the child acquires speech during Piaget’s pre-operational stage, distinctions between right and wrong are taught by parents and other authority figures. The child learns the value of cooperation (e.g., “I’ll scratch your back and you scratch mine”) once making friends and interacting with others. Conventional morality is based on reference to an authority figure (e.g., parent, teacher, clergy member, etc.) at first and then advances to written sources (e.g., the Bible, Koran, Constitution, etc.). The child acquires a more abstract and flexible understanding of morality once progressing to the stages of concrete and formal operations, . The highest (and rarest) Post-conventional morality level is based on the application of universal principles such as the Golden Rule (Do unto others as you would have others do unto you).


File:Kohlberg Model of Moral Development.svg


Figure 8.3 Kohlberg’s stage theory of moral development.


In attempting to teach codes of moral conduct, much parenting consists of the intentional or non-intentional administration of appetitive and aversive events. We may consider how the different parental styles implement learning procedures and how they may relate to Kohlberg’s levels of moral development (see Figure 8.12).

Negligent                      Indulgent                  Authoritarian            Authoritative

Unavailable to monitor behavior, administer consequences consistently, or provide explanations Available to administer non-contingent presentation of appetitive events and provide praise Available to administer contingent presentation of mostly aversive events without explanation Available to administer contingent presentation of appetitive and aversive events with explanation
Pre-Conventional morality Sense of entitlement Conventional morality Post-Conventional morality

Figure 8.4 Parental styles and stages of morality (adapted from Levy, 2013).


Indifferent parents (low demandingness, low responsiveness) do not specify codes of conduct or respond to their children’s needs. If other people (siblings, relatives, peers) do not provide rules and/or consequences, the children will most likely base right and wrong on the outcomes of their actions (if it feels good it is right; if it feels bad it is wrong). Indifferent parenting would appear to be most likely to produce pre-conventional reasoning in children. The authoritarian parenting style would appear likely to result in conventional reasoning and the authoritative style in post-conventional reasoning. Ideally, by providing reasons and explanations in age-appropriate language, our children would internalize principles of moral conduct and apply them appropriately throughout their lives.

Indulgent parents (low demandingness, high responsiveness) do not specify codes of conduct but are affectionate and responsive. They provide “unconditional positive regard” (Rogers, 1957), the type of non-contingent appetitive consequence likely to result in “spoiling” and a sense of entitlement. This could create problems for the children in other contexts (e.g., school, playgrounds) when others react differently to their behavior.

Authoritarian parents (high demandingness, low responsiveness) specify strict codes of conduct in a non-responsive manner. If the children ask for reasons, they may reply “because I say so!” In their parents’ absence, the children would seek other sources of authority.

Authoritative parents (high demandingness, high responsiveness) specify strict codes of conduct within a context of warmth and sensitivity to the children’s needs. They are likely to provide reasons for their codes of conduct, listen to their children’s perspective, and in instances, negotiate alternative codes.

It is very difficult to administer punishment immediately and on a consistent basis in the natural, free-living environment. Therefore, it is not likely that punishment will work as intended, to suppress undesired behavior. Often, instead, the child will learn to become deceptive or lie in order to avoid being punished. Indifferent parents are not likely to be present to appropriately administer punishment and will probably be inconsistent. Indulgent parents are less likely to administer punishment than other parents, if at all. Authoritarian parents (“my way or the highway”) might effectively suppress the undesired behavior when they are present. However, the behavior may occur when they are not present or when the child is in different situations. Authoritative parents, taking advantage of their children’s verbal and reasoning skills, probably have the greatest likelihood of attaining the desired result. For example, an older sibling picking on a younger one might be told the following scenario which includes stipulation of rules of conduct:

There is a difference between a jungle and a society. In the jungle, strong animals often attack weaker animals who receive no protection. Human beings have families and societies in which the strong protect the weak and help them grow stronger. You have to decide whether you want to live in our family and be a member of society. If you keep picking on your little brother/sister, we will need to treat you like an animal from the jungle. We put dangerous animals in a zoo so they cannot hurt anyone, so we will keep you in your room. If you take care of your little brother/sister, mommy and daddy will let you play together and have fun.

By relying upon language to stipulate and enforce rules in this manner, a parent is most likely to achieve the short-term objective of encouraging appropriate and discouraging inappropriate behavior. In addition, by providing thoughtful explanations and justifications of rules, the parent increases the likelihood that the child will internalize a moral code of conduct as he/she matures.


Relate control learning principles to Kohlberg’s stages of moral development.

Erik Erikson’s Stage Theory of Lifespan Development

Erik Erikson (1950; 1959) proposed a “cradle to grave” sequence of development which complements the stage theories of Piaget and Kohlberg. Erikson described eight “conflicts” associated with different periods of one’s life (see video). It was assumed that successful resolution of the conflict associated with a particular stage resulted in acquisition of the related “virtue” (e.g., trust, autonomy, initiative, etc.) for the rest of one’s life. Unsuccessful resolution would result in developmental problems during subsequent stages.


Watch the following video of Erikson’s stages of development:


During Erikson’s first (infancy) stage, taking place during Piaget’s pre-verbal sensorimotor stage, the attachment style of the caregiver will influence whether or not the infant experiences a nurturing and responsive social environment. If the caregiver is consistent in satisfying the basic needs for food, comfort, and relief from pain, the infant learns to trust them. If negligent, inconsistent, or abusive, the child will mistrust and perhaps fear the caregiver.

In the second (early childhood) stage, starting toward the end of Piaget’s sensorimotor stage and extending into the beginning of the verbal preoperational stage, the young child is exploring and learning to control the environment on its own. A patient caregiver waits until the zone of proximal development is reached and applies encouraging, supportive scaffolding techniques during toilet training and other learning experiences. Such a parent is likely to insure the child’s success, resulting in the feeling of independence and autonomy. If the child is hurried, scolded, or punished for failures, she/he may feel shame and doubt her/his capabilities.

In the third (preschool) stage, occurring in the middle of Piaget’s preoperational stage, the child must learn to dress and groom in a manner consistent with social norms and standards. If the child is encouraged to explore options, satisfy its curiosity, and express its own preferences and interests, it is likely to develop initiative. If discouraged, the child may become passive and doubtful of its own capabilities and experience guilt regarding its choices.

Erikson’s lengthy fourth (school age) stage starts toward the end of Piaget’s preoperational stage and extends through concrete operations into the beginning of the final formal operations stage. If at home and school, the child is appropriately challenged and succeeds at progressively more difficult tasks, it becomes competent, confident, and industrious. The child must experience and learn to cope with frustration and inevitable failure. It is during this stage that the child becomes concerned about its own performance in comparison to others in and out of school. Feelings of inferiority can result from perceived inadequacies and negative social comparisons.



Figure 8.3 “Kohlberg’s stages of moral development” by Lawrence Kohlberg is licensed under CC BY-SA 4.0





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

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