Chapter 2.docx

**Chapter 2** **Theories of Development** **Biological and Evolutionary Theories** Understanding biological processes is crucial for grasping evolutionary theories of development. Both genetic and epigenetic factors, in interaction with environmental variables, influence our health and well-being throughout our lives. We are in the early stages of understanding how epigenetic processes merge nature and nurture, which could significantly alter our perception of human development. Evolutionary theories suggest that the genetic and physiological processes driving human behavior have gradually evolved over time due to genetic mutations and natural selection. These theories are used to explain not only cognitive behavior but also social and cultural behavior. **Genetics** The nuclei of our body cells contain 23 pairs of chromosomes, which are composed of nearly 2.0 metres of tightly coiled DNA molecules. Each chromosome has segments known as genes, each influencing a specific trait or developmental pattern. A gene controlling a particular characteristic is always located at the same place (the locus) on the same chromosome in every individual of the same species. For instance, the locus of the gene determining a person's blood type (A, B, or O) is on chromosome 9. A genome encompasses all the DNA an organism has. To understand the complexity of the genome, consider that each of our 46 chromosomes contains anywhere from a few dozen to a couple of thousand genes. In total, each human body cell nucleus has an estimated 19,000 to 22,000 protein-coding genes. - **DNA and Base Pairs**: DNA (Deoxyribonucleic Acid) is a molecule that carries most of the genetic instructions used in the development, functioning, and reproduction of all known living organisms. It is composed of two strands forming a double helix structure. Each strand is made up of four types of organic compounds or bases: Adenine (A), Thymine (T), Cytosine, and Guanine (G). These bases pair up with each other to form base pairs: A with T and C with G. - **Human Genome and Chromosomes**: The human genome is the complete set of DNA in a human being. This DNA is organized into 23 pairs of chromosomes located in the nucleus of our body cells. Each chromosome contains strands of genes. - **Nucleosomes and Histones**: The DNA in our cells is wound around proteins called histones. This combination of DNA and histones forms a bead-like structure called a nucleosome. - **Epigenetic Markers and the Epigenome**: Along the nucleosomes are epigenetic markers, which are chemical modifications that do not change the DNA sequence but can affect gene activity. Collectively, these markers make up the epigenome. - **Gene Expression and Chromatin**: Epigenetic markers control gene expression by influencing the structure of chromatin, which is a complex of DNA and protein found in cells. When the chromatin is loosely packed (open), gene expression is possible because the genes are accessible for transcription and translation into proteins. Conversely, when the chromatin is tightly packed, the genes are silenced because they are not accessible for transcription. Genes play a crucial role in directing body cells to combine 20 standard amino acids to construct the necessary proteins for our bodies to function optimally. Proteins, which are organic compounds, form the body's structures and regulate its upkeep. Fundamental structural elements of our bodies, such as muscle, brain, and bone, consist of various proteins. Additionally, proteins govern all biological processes, from metabolic and immune functions to intercellular communications. **Genotypes, Phenotypes, and Patterns of Inheritance** The genotype refers to the actual DNA material that forms each person's unique genetic blueprint. On the other hand, the phenotype is the set of observable characteristics of an individual. The phenotype can be directly observed, such as a woman's brown eyes. However, determining the genotype isn't as straightforward. In many instances, knowledge about the eye color of her parents and offspring would be necessary to ascertain if she carries genes for a different eye color. This is due to the complex rules that dictate how genotypes influence phenotypes. Patterns of inheritance are explained by three principles of genetic transmission. **Dominant and Recessive Genes** The most basic rule in genetics is the dominant-recessive pattern, where a single dominant gene significantly impacts the phenotype. Individuals with either two dominant or two recessive genes on their chromosomes are termed as homozygous. Conversely, individuals with one dominant and one recessive gene are known as heterozygous. ![A screenshot of a table Description automatically generated](media/image2.png) A child's phenotype will display a trait determined by a dominant gene if they inherit it from one parent. However, a recessive trait will only be part of a child's phenotype if they inherit the recessive gene from both parents. For instance, the curliness of hair is governed by a pair of genes. The gene for curly hair is dominant, so a man with curly hair has at least one gene for curly hair, and at least half of his sperm carry this gene. On the other hand, straight hair is recessive, meaning a man with straight hair must have two straight-hair genes for his phenotype to include straight hair. Therefore, a straight-haired father can only pass on straight hair to his children, as all his sperm carry the recessive straight-hair genes. Both dominant and recessive genes vary in expressivity, which means the extent to which a gene affects phenotypes can differ among individuals. For instance, not all people with the gene for curly hair have the same degree of curliness. Therefore, even if a child inherits a dominant gene for curly hair from her father, the curliness of her hair may not exactly match his. Blood type is determined by a dominant-recessive inheritance pattern. A person needs two recessive genes to have type O blood, making their genotype clear. The genotype of people with type A or B blood isn't as clear because types A and B are dominant. Therefore, a person with type A or B blood must have one gene for that type, but the other gene could be for a different type. If a type A father and a type B mother have a child with type O blood, both parents must carry a gene for type O, as the child needs to inherit this gene from each parent to have the type O phenotype. **Polygenic and Multifactorial Inheritance** In polygenic inheritance, multiple genes contribute to the phenotype. Many polygenic traits also follow the dominant-recessive pattern. For instance, it's believed that children inherit three genes for skin color from each parent. Dark skin is dominant over light skin, but the skin colors also blend. Therefore, if one parent has dark skin and the other has light skin, the child's skin color will be a blend of the two. The dark-skinned parent's dominant genes will make the child darker than the light-skinned parent, but the light-skinned parent's genes will prevent the child from having skin as dark as the dark-skinned parent. Eye color is a polygenic trait that follows a dominant-recessive pattern. The exact number of genes influencing eye color is unknown to scientists. These genes don't result in specific colors but determine whether the colored part of the eye is dark or light. Dark colors (black, brown, hazel, and green) are dominant over light colors (blue and grey). Blended colors are also possible. Individuals with a mix of genes for green, blue, and grey eyes can have blue-grey, green-blue, or blue-green eyes. Similarly, genes causing different shades of brown can combine their effects, resulting in children's eye color phenotypes that differ from those of their brown-eyed parents. Many physical traits, such as height, are influenced by both genes and environment, a concept known as multifactorial inheritance. Numerous genes contribute to a child's height and growth rate. However, factors like illness, poor nutrition, or emotional neglect can result in a child being smaller than their peers, despite having genes that should make them as tall. Therefore, if a child is shorter than 97% of their peers, doctors may investigate whether the short stature is due to genetic factors or other growth-inhibiting conditions. Psychological traits like intelligence and personality are shaped by both genetics and environment. Many neurodevelopmental disorders, which are conditions causing atypical neurological development in children, often arise from multifactorial inheritance, a combination of genetic and environmental factors. These disorders include intellectual disabilities, communication disorders, autism spectrum disorders, and attention-deficit/hyperactivity disorder. **Mitochondrial Inheritance** Scientists have found additional principles of genetic inheritance related to genetic material in the mitochondria of a woman's eggs, not in the nucleus. In mitochondrial inheritance, children inherit genes located in the mitochondria, which are in the fluid surrounding the ovum's nucleus before fertilization. As a result, mitochondrial genes are only passed from mother to child. Several serious disorders, including certain types of blindness, are transmitted this way. Interestingly, in most cases, the mother carrying these harmful genes remains unaffected. **Epigenetics** Current genetics research indicates that our genome only represents one aspect of hereditary influences. A longstanding question has been how cells carrying the same genome can differentiate into specialized cells, such as liver, heart, or brain tissue. The answer lies in the discovery of the epigenome, molecular biological compounds that overlay our DNA. These compounds play a crucial role in cell differentiation. Efforts are underway, such as those by the International Human Epigenome Consortium (IHEC), to map the human epigenome and identify specific epigenetic markers associated with gene regulation, cell differentiation, and human health and disease across the lifespan. Having a gene for a specific trait doesn't ensure its expression. While each cell in our body has the same genetic code (genotype), our unique set of epigenetic markers regulate gene expression (phenotype). These markers signal certain genes to "turn on" (gene expression) and others to "turn off" (gene silencing). For instance, post-conception, epigenetic markers activate "brain genes" in brain tissue but keep them inactive in liver tissue. Epigenetic structures also regulate ongoing cellular functions by signaling a gene or polygene to turn on or off as needed. This way, epigenetic mechanisms control normal bodily processes like blood sugar regulation, immune function activation, or brain cell activity. Epigenetics researchers Moshe Szyf and Michael Meaney from McGill University, along with Ian Weaver from Dalhousie University, have discovered that epigenetic factors significantly influence development throughout life. Their animal studies were the first to show that maternal care can physically modify molecular epigenetic structures in offspring. For instance, increased postnatal feeding and grooming by a mother rat led to calmer pups by actually changing the pups' molecular epigenetic structures. They also found in subsequent studies that these early-life epigenetic changes, while persistent into adulthood, could be experimentally reversed. While epigenetic modifications gained during a parent's lifetime are usually erased during the early stages of prenatal development in subsequent generations, some acquired epigenetic changes can be inherited. Animal studies have shown that epigenetic alterations to proteins in the liver, heart, and brain in mice, as well as endocrine, reproductive, and behavioral changes in rats, can be passed on to offspring. Epigenetic changes induced by alterations in maternal diet and paternal stress have also been shown to be transmissible across generations in mice. There is growing evidence suggesting that acquired epigenetic traits can be inherited across generations in humans as well. Interest in epigenetics has been growing since the start of the millennium. Besides studying the link between epigenetic changes and health and disease, the field is expanding into specialized areas like behavioural epigenetics. This involves studying epigenetic changes related to brain development, behaviour, and psychological processes in response to environmental factors. Key research areas include parenting styles, cognition (learning and memory), neurological and mental disorders, stress, substance use, and suicidal behaviour. **Evolutionary Theories** Evolutionary theories attempt to explain our differences as individuals and our commonalities as a species. These theories often focus on the genetic and environmental mechanisms that underlie development throughout the lifespan and across generations. **Ethology** Ethology emphasizes genetically determined survival behaviours that are assumed to have evolved through natural selection. For example, nests are necessary for the survival of young birds. Therefore, ethologists say, evolution has equipped birds with nest-building genes. Ethologists argue that emotional bonds, crucial for human infant survival, are a result of evolutionary genetics. They suggest that genes cause humans to form these bonds. For instance, a newborn's cry, which is genetically programmed to be irritating, prompts a response from adults. This response, aimed at stopping the irritating noise, leads to interaction between the caretaker and the infant, forming an emotional bond. Consequently, this bond enhances the infant's survival chances. Thus, the genes responsible for the irritating cry indirectly contribute to the infant's survival. **Behaviour Genetics** Behaviour genetics is a field of study that examines the impact of heredity on individual differences. It posits that genes influence traits or behaviours, as evidenced when relatives exhibit more similarities in these areas than unrelated individuals. Research in this field has demonstrated that heredity influences a wide array of traits and behaviours, including intelligence, altruism, substance use and abuse, and hyperactivity. **Evolutionary Psychology** Evolutionary psychology is a comprehensive approach that seeks to explain human behavior by integrating all branches of psychology and life sciences. It specifically investigates the evolution of inherited cognitive and social traits through natural selection. A key area of focus is the adaptation of neural networks that facilitate cognitive abilities essential for social relations and interactions. Steven Pinker, a Harvard psychologist from Montreal, is a prominent proponent of evolutionary psychology. He posits that the mind, akin to the body, has evolved through natural selection to perform adaptive functions and enhance survival. Pinker asserts that we possess innate patterns of thought and emotion, shaped over time by survival necessities. This "human nature," as he terms it, influences all facets of our lives, ranging from child-rearing practices and political views to our preferences in art and music. **Evolutionary Developmental Psychology** Advocates of this perspective argue that, contrary to philosopher John Locke's belief, a newborn's mind is not a blank slate. Instead, it is genetically predisposed to learn and develop in specific ways, such as being ready to learn language and recognize human faces. Evolutionary developmental psychology theorists concur that both nature (genes) and nurture (environment) play a role in shaping an individual's intelligence, personality, and social behaviour. They also propose that different stages of life require different behavioural responses. For instance, the cognitive and emotional skills that aid infants and children in adapting and surviving differ significantly from those needed by adults. Infants need to form attachments, while adults deal with mating, parenting, and eventually grandparenting. Therefore, evolutionary forces have led to the development of age-specific strategies that enhance survival and adaptation throughout a person's life. **Evolutionary Prenatal Programming and Adult Health and Disease** Evolutionary theorists Peter Gluckman and Mark Hanson propose that lifestyle changes later in life may be insufficient to reduce disease risk. They argue that the risk of non-communicable diseases like heart disease, diabetes, and obesity may be influenced by early life factors. They suggest that a fetus picks up environmental cues from its mother, allowing it to anticipate its postnatal environment and undergo epigenetic changes for survival. These predictive-adaptive responses are beneficial only if the forecast is accurate. A mismatch between the prenatal and postnatal environments can lead to physiological adaptations that are ill-suited to the postnatal environment, contributing to lifestyle-related diseases in adulthood. The greater the mismatch, the higher the risk. This theory explains how such mismatches can predict metabolic disease. During prenatal and early postnatal life, the developing organism senses environmental cues, such as undernutrition, transmitted by the mother. These cues trigger developmental flexibility, altering the default trajectory set by the inherited fetal genome and epigenome based on the perceived adequacy of the environment. This leads to metabolic adjustments. If the mature environment matches the predicted one, the risk of metabolic disease in later life is low. However, if there's a mismatch, especially if the mature environment is richer than expected, the risk of metabolic disease increases. Certain responses of an embryo or fetus to its environment may be developmentally disruptive and lack adaptive value, such as a response to a toxic environmental agent that exceeds the organism's adaptive capacity. Epigenetic changes to DNA made prenatally can last a lifetime, and responses to predicted future environmental conditions can span several generations. A gene variation that may have facilitated adaptation for generations can suddenly trigger an epidemic when lifestyle behaviors change. **Applying Biological and Evolutionary Theories** Biological principles that underlie genetics and epigenetics are expanding our understanding of disease processes. Scientists are discovering the complex role that inheritance plays in human health and the related importance of early intervention. **Disease Control** Advancements in human genomics are expected to significantly contribute to disease prediction and prevention. While some scientists believe that progress in rare single-gene diseases like hemophilia, Huntington's disease, and sickle-cell disease will have limited impact on overall healthcare, as these account for only about 5% of all human diseases in developed countries, others anticipate the most substantial impact to be in the treatment of multifactorial diseases like heart disease and cancer. A genome-wide perspective is seen as beneficial in these cases. For instance, a research team led by Samuel Aparicio at the British Columbia Cancer Agency decoded the DNA sequence of a type of breast cancer that represents 10% of all breast cancers. Following this breakthrough, Canadian scientists joined an international effort to decode the genomes and epigenomes of approximately 25,000 cancer samples, aiming to develop new strategies for early detection and prevention. Alongside genomics, epigenomics is swiftly enhancing our comprehension, diagnosis, and treatment of human diseases and disorders. Epigenomics studies how epigenetic changes, which continually modify DNA markings throughout a person's life, affect gene expression and increase the risk of developing both physical and psychological disorders. Acquired epigenetic traits or predispositions can be passed onto subsequent generations. Newly discovered epigenetic factors could potentially serve as the "missing link" in explaining the interaction between nurture and nature. **Early Intervention** Evolutionary theory and research are increasing scientists' understanding of the significant impact of early-life events on the susceptibility to chronic diseases and socioeconomic disadvantages in later life. This awareness has shifted focus towards the need for early intervention strategies, not just during prenatal development, but also before conception, such as promoting good health, nutrition, and social security in women of reproductive age. These early interventions could potentially prevent or at least reduce chronic diseases and social disadvantages in future generations. **Research Report** **Type 2 Diabetes Epidemic in a Remote Community** Before the mid-20th century, type 2 diabetes was uncommon among Indigenous populations. However, by the 1970s, an epidemic seemed to be emerging, which was confirmed two decades later. Currently, in Canada, type 2 diabetes is three times more prevalent in First Nations peoples than in the general population, with an estimated 20% of all First Nations peoples living with the disease. Type 2 diabetes, which typically develops later in life, leads to serious health and social consequences, including heart disease, blindness, kidney failure, and gangrene. It is a leading cause of death and disability among First Nations peoples. A research team led by Robert Hegele at the John P. Robarts Research Institute discovered a strong genetic effect related to a single gene variant, the G319S mutation, in the Oji-Cree community. This mutation, which affects a specific liver protein, has led to an incidence of type 2 diabetes five times higher than in the general Canadian population. The type 2 diabetes epidemic illustrates the interaction between genes and behavior, suggesting that genetic susceptibility interacts with multiple environmental factors. The sudden increase in disease incidence may be linked to significant lifestyle changes. For example, the Oji-Cree's traditional low-carbohydrate diet has been replaced by a diet high in "junk food" and fats, coupled with a more sedentary lifestyle. This modern lifestyle promotes midbody obesity in Oji-Cree individuals with the G319S mutation, leading to a higher risk of diabetes. The understanding of the interaction between genetics and environment has led to a comprehensive healthcare initiative for the Oji-Cree community. This includes community-wide prevention and health education programs starting from Grade 3, emphasizing healthy lifestyle practices like a balanced diet and physical exercise. Additionally, a diabetes screening program and a support program for those living with the disease have been established to mitigate its effects. **Psychoanalytic Theories** One explanation for why babies often put objects in their mouths is that infants gain more physical pleasure from mouthing objects than from handling them with other body parts. This perspective aligns with psychoanalytic theories, a school of thought initiated by Sigmund Freud. Psychoanalytic theorists propose that internal drives and emotions drive developmental change. **Freud's Psychosexual Theory** Freud's developmental theories were largely based on his work with adults with serious mental disorders, analyzing their childhood memories. He concluded that behavior is influenced by both conscious and unconscious processes. Among these, the libido, an unconscious drive for physical pleasure, was considered by Freud as the primary motivator for most behaviors. **Personality Development** Freud's work with patients who had memories of childhood sexual feelings led him to believe that these feelings play a crucial role in personality development. He proposed that personality comprises three parts: the id, ego, and superego. The id, present at birth, contains the libido and operates unconsciously, driving basic sexual and aggressive impulses. The ego, which develops in the first two to three years of life, is the conscious part of the personality tasked with satisfying the id's needs. For example, when a person feels hunger, the id demands immediate food, and the ego seeks to fulfill this demand. The superego, which develops around age 6, acts as a moral judge and contains societal rules. Once the superego develops, the ego's task becomes more complex as it must satisfy the id without breaking the superego's rules. Freud posits that the ego is tasked with maintaining balance among the three components of personality: the id, ego, and superego. Tension arises when these components conflict. For instance, if a person is hungry, the id might drive her to find food at all costs, but the ego, her conscious self, might struggle to do so. Alternatively, the ego might need to break a moral rule of the superego to obtain available food. In such scenarios, the ego may employ defence mechanisms, or ways of thinking that alleviate anxiety. Without these mechanisms, Freud believed, the internal tension could become unbearable, potentially leading to mental disorders or suicide. **Five Psychosexual Stages** Freud proposed a sequence of psychosexual stages that a child progresses through, each stage characterized by the libido's focus on a different body part. The stages are as follows: - **Oral stage**: In infancy, the mouth is the center of pleasure. - **Anal stage**: As the child matures, the focus shifts to the anus. - **Phallic stage**: Later, the libido centers on the genitals. - **Latency stage**: This is a period of dormancy. - **Genital stage**: After latency, the focus returns to the genitals. Each stage is determined by the child's maturation and has a significant impact on their development. Freud posits that optimal development necessitates an environment that caters to the distinct needs of each developmental stage. For instance, infants require ample opportunities for oral stimulation. An insufficient early environment can lead to fixation, which is marked by behaviors indicative of unresolved issues and unfulfilled needs. Therefore, the importance of early experiences in shaping development is a key aspect of psychoanalytic theories. **Erikson's Psychosocial Theory** Erik Erikson, a prominent psychoanalytic theorist, greatly influenced the study of development. While he accepted many of Freud's ideas, Erikson expanded upon them. He proposed that development is the result of the interaction between internal drives and cultural demands, leading to his theory of psychosocial stages, as opposed to Freud's psychosexual stages. Erikson also believed that development continues throughout the entire lifespan. **Eight Psychosocial Crises to Resolve** Erikson's theory posits that a healthy personality is achieved by successfully resolving a psychosocial crisis at each of the eight stages of development. Each new crisis arises due to changes in social demands that correspond with age changes. Each crisis is characterized by a pair of opposing possibilities, and successful resolution leads to the development of the positive characteristic. However, a healthy resolution doesn't mean completely leaning towards the positive side. For instance, an infant needs to experience some mistrust to learn to identify untrustworthy individuals. Thus, healthy development necessitates a favorable balance of positive to negative experiences. Erikson's theory posits that the four childhood stages lay the groundwork for adult personality: - The **first stage**, trust versus mistrust (birth to 1 year), hinges on the dependability of care and affection provided by the primary caregiver. - The **second stage**, autonomy versus shame and doubt (ages 1 to 3), is when children start expressing their independence. Caregivers should encourage them to develop self-care skills, like dressing themselves, to resolve this stage successfully. - In the **third stage**, initiative versus guilt (ages 3 to 6), children begin to cultivate a sense of social initiative, which requires opportunities to interact with peers. - The **fourth stage**, industry versus inferiority (ages 6 to 12), sees children focusing on acquiring skills valued by their culture. To successfully navigate this stage, children need adult support and encouragement. Erikson's stages of adulthood are not strictly age-related. The first stage sees young adults building on their adolescent identities to tackle the crisis of intimacy versus isolation. Erikson theorized that an individual's ability to form intimate relationships depends on successfully resolving their identity crisis. He believed that many young people mistakenly seek their identity in relationships. However, in his view, only those who have already formed a clear identity, or are in the process of doing so, can successfully achieve the fusion of identities he termed as intimacy. Young adults with weak or unformed identities tend to have superficial relationships and often experience feelings of isolation or loneliness. The crises in middle and late adulthood are influenced by the awareness of mortality. Middle-aged adults face the crisis of **generativity versus stagnation**, which involves the responsibility of nurturing the next generation. This can be achieved through parenting, creative work, societal service, or mentorship. Failure to do so can lead to a feeling of stagnation. Older adults, on the other hand, confront the crisis of **ego integrity versus despair**. The objective here is to accept one's life as it has been lived, in preparation for death, to prevent feelings of despair. **The Humanistic Alternative** Unlike psychoanalytic theories that emphasize abnormal development, some psychologists propose alternative theories focusing on positive development aspects. These theories, known as humanistic theories, accept the psychoanalytic assumption of behavior being driven by internal drives and emotions. They align with Jean-Jacques Rousseau's belief in innate goodness and posit that the primary internal drive is an individual's motivation to realize their full potential. Abraham Maslow, a significant figure in humanistic psychology, termed this ultimate life goal as **self-actualization**. **Motives** Maslow's primary interest was in the development of motives or needs, which he categorized into two groups: **deficiency motives** and **being motives**. Deficiency motives are drives to maintain physical or emotional balance, such as the need for food, drink, sex, or even sufficient love or respect from others. Being motives, on the other hand, involve the desire to understand, to give to others, and to grow, leading to self-actualization. Generally, satisfying deficiency motives helps prevent or cure illness and restore balance, while satisfying being motives leads to a sense of well-being. The difference is akin to defending against threats versus achieving positive triumphs. Maslow proposed a hierarchy of needs, which must be satisfied in a sequential order, starting from the bottom of the pyramid. Physiological needs come first, followed by safety needs. Only after love and esteem needs are met can an individual strive for self-actualization. Maslow believed that being motives become significant in adulthood, specifically in individuals who have consistently met their love and esteem needs. This aspect of Maslow's theory bears resemblance to Erikson's stages of intimacy and generativity. According to Maslow, needs in his hierarchy operate sequentially from the bottom up. Physiological needs must be satisfied first before other needs become prominent. Once physiological needs are met, love needs emerge, followed by esteem needs, and so on. This hierarchy also has a developmental aspect: a baby's primary needs are physiological, toddlers are safety needs, and so forth. The need for self-actualization becomes central only in adulthood. **Personal Growth** Prominent humanistic psychologist Carl Rogers discussed the potential of each individual to become a "fully functioning person" without excessive guilt or significant defenses. Early experiences with caregivers who conditionally accept a child based on their behavior can undermine the child's self-esteem, leading them to believe they are only valuable when they behave in approved ways. However, Rogers believed that it's never too late to overcome early conditioning or unresolved issues. He asserted that individuals have the potential and motivation to pursue personal growth. **Learning Theories** Learning theories propose that development is a result of accumulated experiences. They align with John Locke's philosophy, suggesting that children are born neutral, and their behavior is molded by their environment. This contrasts with psychoanalytic and humanistic views. Learning theorists argue that infants repeat behaviors, like mouthing objects, because they find the sensations rewarding. Conversely, if an object tastes bad, infants learn to avoid mouthing such objects. A central learning theory, known as behaviourism, views development in terms of behaviour changes caused by environmental influences---a process called conditioning. As you will see, there are two ways that conditioning changes our behaviour. **Pavlov's Classical Conditioning** Ivan Pavlov, a Russian physiologist, and Nobel laureate discovered that organisms can learn new signals for existing behaviors, a principle known as **classical conditioning**. Each learning instance starts with a biologically programmed stimulus-response connection or reflex. For instance, salivation is a natural response to food in the mouth. In terms of classical conditioning, the food is the unconditioned (unlearned, natural) stimulus, and salivation is the unconditioned (unlearned, natural) response. **The Conditioning Process** In classical conditioning, an **unconditioned stimulus** (like food) naturally triggers an **unconditioned response** (like salivation). Now, if another stimulus (like the smell of food) is consistently presented just before or at the same time as the unconditioned stimulus, it becomes associated with it. Over time, this new stimulus (the smell of food) becomes a **conditioned stimulus**. It's "conditioned" because the association is learned through repeated pairings with the unconditioned stimulus (food). This conditioned stimulus can then elicit the same response (salivation) even in the absence of the unconditioned stimulus. In this example, the smell of food becomes a signal to your salivary glands that food is coming, triggering salivation. This salivation in response to the smell of food, even when you're not eating, is known as a **conditioned response** because it's a learned reaction to the conditioned stimulus (the smell of food). This demonstrates how our behaviors can be shaped by associations formed through classical conditioning. **Early Conditioning** Classical conditioning plays a significant role in emotional development. It involves associating certain stimuli with specific feelings. For instance, objects or individuals present during pleasant experiences can become conditioned stimuli for positive emotions. Conversely, those associated with discomfort can trigger feelings of unease. This process is particularly crucial during infancy. Parents, being frequently present during comforting experiences, often become conditioned stimuli for positive feelings. This association enables a child to find comfort in their parents' presence. **Skinner's Operant Conditioning** Operant conditioning, a concept introduced by B.F. Skinner, is a type of learning where behaviors are influenced by their consequences. If a behavior leads to a favorable outcome (**reinforcement**), it's more likely to be repeated. Conversely, if a behavior results in an unfavorable outcome (**punishment**), its recurrence is likely to decrease. **Reinforcement** **Positive reinforcement** involves adding a pleasant consequence after a behavior, increasing the likelihood of its repetition. For instance, attention can serve as a reinforcer. However, a consequence is only considered reinforcing if it effectively increases the behavior's probability. **Negative reinforcement**, on the other hand, involves removing an unpleasant condition following a behavior, which also increases the likelihood of the behavior's repetition. An example is taking cough syrup to alleviate coughing. The act of taking the syrup is reinforced by the cessation of the unpleasant coughing, teaching us to reach for the syrup when we start coughing. This is how behaviors are learned through negative reinforcement. Positive and negative reinforcement can be complex in real-life situations. For instance, a preschooler's whining can illustrate both. When a parent pays attention to a child's whining, it often increases, showing **positive reinforcement** as the child's behavior is reinforced by the parent's attention. Simultaneously, the parent learns to respond to the whining because it's irritating and responding usually stops it. This is an example of **negative reinforcement**. The parent's behavior of responding is reinforced by the cessation of the child's whining. So, in this scenario, the parent's attention is negatively reinforced when the child stops whining. **Punishment** There are two forms of punishment, both aimed at stopping a behavior. One form, known as **negative punishment**, involves removing something pleasant following a behavior, which decreases the likelihood of the behavior's repetition. For instance, taking away TV privileges is a negative punishment. This can be seen as a type of extinction, a process where a behavior is gradually eliminated through consistent non-reinforcement. If a teacher manages to stop a student's undesirable behavior by ignoring it, the behavior is considered to have been extinguished. Positive punishment involves introducing an unpleasant consequence after a behavior, which decreases the likelihood of the behavior's repetition. An example is scolding. However, like reinforcement, punishment is defined by its effect. If a consequence doesn't stop a behavior, it can't be considered a punishment. **Changing Behaviour** Reinforcements and punishments operate in complex ways in real-world settings, differing from controlled laboratory environments. In labs, operant conditioning researchers typically work with a single participant or animal, allowing them to control the situation and consistently reinforce specific behaviors. However, in real-world scenarios, **partial reinforcement**---where a behavior is reinforced only sometimes---is more common. Studies indicate that while learning new behaviors under partial reinforcement conditions takes longer, once established, these behaviors are highly resistant to extinction. Shaping involves reinforcing incremental steps to teach a complex behavior. In learning to play tennis, this means starting with basic skills like holding the racquet, then progressing to hitting balls, learning to serve, and finally playing a match. Each step is encouraged by the satisfaction of accomplishing these intermediate goals. **Development in the Real World** **Learning Principles in Real Life** In real-life situations, principles of learning operate in complex ways. For instance, if a child persistently demands attention and the parent responds after several attempts, the parent inadvertently creates a **partial reinforcement schedule**. The child learns that persistent demands will eventually be rewarded with attention, making the behavior hard to extinguish. Furthermore, reinforcement can shape behaviors mutually in interactions. For example, if a child hollers at his mother for his lunch bag and she complies, two things occur. Firstly, the child's hollering behavior is strengthened through **positive reinforcement** as he gets what he wanted. Secondly, the mother's obliging behavior is strengthened through **negative reinforcement** as the distressing hollering stops. This illustrates how behaviors can be mutually reinforced in interactions. This passage discusses the concept of **reciprocal reinforcement** in parent-child interactions. It suggests that a child's behavior, such as hollering, can inadvertently be reinforced by a parent's response, such as giving in to the child's demands. This creates a pattern that benefits the child but may disadvantage the parent. Once established, these patterns can be hard to break, particularly if the reinforcing sequence of events is not recognized. The passage recommends that if such patterns are familiar, it could be beneficial to keep detailed records of incidents and responses. This could help in identifying the underlying principles at work and in devising strategies to change the pattern. **Cognitive Theories** Cognitive theories focus on the mental aspects of development, such as logic and memory. These theories suggest that babies engage in repetitive actions, like throwing objects from a shopping cart, to build their understanding of the world. By using their motor skills and senses, they create mental images of their surroundings. This repetitive behavior continues until they have learned all they can from it, after which they progress to more mature interactions with the world. **Piaget's Cognitive-Developmental Theory** Jean Piaget (1896--1980), a developmental psychologist, was primarily interested in understanding how thinking develops. He observed that children universally go through the same sequence of learning about their world, often making identical mistakes and arriving at the same solutions. For instance, most 3- and 4-year-olds believe that pouring water from a short, wide glass into a taller, narrower one increases the amount of water, because the water level appears higher. However, by the age of 7, most children understand that the quantity of water remains unchanged. Piaget proposed several concepts to explain these age-related differences, which continue to influence developmental research. **Schemes** A pivotal idea in Piaget's model is that of a scheme, an internal cognitive structure that provides an individual with a procedure to follow in a specific circumstance. For example, when you pick up a ball, you use your picking-up scheme. To throw the ball to someone, you use your looking scheme, your aiming scheme, and your throwing scheme. Piaget proposed that each of us begins life with a small repertoire of sensory and motor schemes, such as looking, tasting, touching, hearing, and reaching. As we use each scheme, it becomes better adapted to the world; in other words, it works better. During childhood and adolescence, mental schemes allow us to use symbols and think logically. Piaget proposed three processes to explain how children get from built-in schemes, such as looking and touching, to the complex mental schemes used in childhood, adolescence, and adulthood. Piaget's theory includes two key processes: **assimilation** and **accommodation**. Assimilation involves using existing cognitive schemes to interpret new experiences. For example, a baby uses their existing grasping scheme to understand the act of grasping a toy. Accommodation, on the other hand, involves modifying existing schemes in response to new information. When a baby grasps a square object for the first time, they adjust their grasping scheme to better handle such objects in the future. Accommodation is crucial for developmental change as it enables us to enhance our skills and restructure our thought processes. **Equilibration** is the process of achieving a balance between **assimilation** and **accommodation** to develop cognitive schemes that align with the environment. For instance, infants often put objects in their mouths, assimilating these objects into their existing mouthing scheme. As they experience different objects, their mouthing scheme accommodates new instructions based on the object's texture and feel. For example, a pacifier, which feels good, is acceptable to mouth, while a dead insect, with its unpleasant texture, is not. This way, the infant's mouthing scheme evolves to better match real-world experiences. **Stages** Piaget's research proposes that logical thinking develops in four stages: 1. **Sensorimotor stage (Birth to 18 months)**: Infants interact with the world using their sensory and motor skills. 2. **Preoperational stage (18 months to \~6 years)**: Children acquire symbolic schemes, like language and imagination, which they use for thinking and communication. 3. **Concrete operational stage (\~6 to 12 years)**: Children start to think logically and can solve problems. 4. **Formal operational stage (Adolescence)**: Adolescents develop the ability to think logically about abstract concepts and hypothetical scenarios. This progression illustrates how cognitive abilities evolve from basic sensory interactions to complex abstract thinking. ![](media/image4.png)According to Piaget, each stage of cognitive development arises from the previous one and involves a significant transformation in a child's thought process. Research supports Piaget's assertion that the sequence of these stages is fixed. However, the rate at which children progress through these stages varies, and some individuals may not reach the formal operational stage even in adulthood. Therefore, the ages associated with each stage are approximate. **Information-Processing Theory** The **Information-Processing Theory** aims to elucidate the way the human mind manages and processes information. Drawing parallels with computer operations, theorists in this field concentrate on three main stages of mental information processing: 1. **Input**: The stage where information enters the mind. 2. **Throughput**: The stage where the input information is processed or transformed using mental programs. 3. **Output**: The final stage where the processed information is utilized to perform actions. This theory essentially views the human mind as a complex information processor, similar to a computer. (Based on Radvansky, 2017) **Memory Processes** The **Information-Processing Theory** places significant emphasis on the study and understanding of memory processes. It dissects memory into three subprocesses: 1. **Encoding**: This involves organizing information for storage in memory. An example would be associating new information with personal experiences for better comprehension. 2. **Storage**: This is the process of preserving the encoded information. 3. **Retrieval**: This involves accessing and extracting the stored information from memory. As information navigates through these memory processes, we employ various mental strategies to manipulate the information. This manipulation aids us in executing mental operations, solving day-to-day problems, and learning new tasks. **Memory Components** Most memory research assumes that the human memory is made up of multiple components. The idea is that information moves through these components in an organized way. (See Figure 2.6.) The process of understanding a spoken word serves as a good example. The process of understanding a word, as per the Information-Processing Theory, involves several steps: 1. **Sensory Memory**: The sounds of the word first enter your sensory memory. Your language experiences help you identify the sound pattern as a word. 2. **Short-term Memory**: The recognized word then transitions into your short-term memory, also known as working memory, where all information processing occurs. 3. **Long-term Memory and Understanding**: The meaning of the word is retrieved from your long-term memory, where information is permanently stored. This meaning is placed back into the short-term memory and linked with the word's sounds, enabling you to understand the word. Each component of memory handles information in a unique way: - **Sensory Memory**: Information continuously flows through sensory memory. Unattended information quickly fades away. - **Short-term Memory**: This has a limited capacity, holding about seven items at a time. However, information can be retained here as long as it's being processed, like when you repeat a grocery list to yourself. - **Long-term Memory**: This has unlimited capacity. Information is often stored in an organized manner, based on meaningful associations. For instance, if you read "Bill wrote a letter to his brother," you might later incorrectly remember the word "pen" being in the sentence. This is because information about the writing process and the tools used are stored together in long-term memory. Juan Pascual-Leone, a psychologist from York University, established **neo-Piagetian theories** using the information-processing theory to explain Piaget's stages. As stated by fellow Canadian theorist Robbie Case, these theories expand on Piaget's theory rather than contradict it. According to neo-Piagetians, older children and adults can solve complex problems, like those in Piaget's research, because they can hold more pieces of information in their short-term memories simultaneously than younger children can. For instance, to solve a problem, a child must be able to think about the appearance of two balls of clay before and after one was rolled into a sausage shape, and also consider how the transformation was carried out, all at the same time in her working memory. Neo-Piagetians argue that children are incapable of performing all this mental work in short-term memory until after the age of 6 or 7. (Based on Case, 1985, 1997) **Vygotsky's Sociocultural Theory** After the Bolshevik revolution in 1917, the newly formed Soviet government appointed Russian psychologist Lev Vygotsky, among others, to develop a school system that would align with the objectives of the communist regime. However, due to historical events such as World War II and the Cold War following his death, Vygotsky's work remained largely unrecognized outside the former Soviet Union for many years. In recent times, however, developmentalists have shown interest in Vygotsky's perspectives on how cultural forces impact individual development. (Based on Vygotsky, 1978; Thomas, 2005) **Social Interactions Build Cognitive Skills** Vygotsky's sociocultural theory posits that complex thinking originates from social interactions, not from a child's individual explorations as Piaget suggested. Vygotsky believed that a child's learning of new cognitive skills is guided by an adult or a more skilled child, who structures the child's learning experience, a process he termed "scaffolding". To create an effective scaffold, the adult must capture and maintain the child's attention, model the optimal strategy, and adapt the entire process to the child's developmental level, also known as the "zone of proximal development". This term refers to tasks that are too challenging for the child to accomplish alone but can be managed with guidance. For instance, when parents assist a beginner reader in sounding out new words, they are providing a scaffold. (Based on Landry, Garner, Swank, & Baldwin, 1996; Rogoff, 1990). Vygotsky's concepts have significant implications for education. Like Piaget, Vygotsky emphasized the importance of active exploration opportunities. However, in a Vygotskian classroom, "assisted discovery" would play a more prominent role than in a Piagetian one. The teacher would provide the "scaffolding" for children's discovery through questions, demonstrations, and explanations. For these assisted discovery processes to be effective, they would need to be within each child's "zone of proximal development". (Based on Tharp & Gallimore, 1988) **Bandura's Social-Cognitive Theory** Albert Bandura, a renowned learning theorist, was born and raised in Alberta. He completed his bachelor's degree in psychology from the University of British Columbia in 1949 and earned his Ph.D. from the University of Iowa in 1952. Bandura's early theory underscored the significance of psychological modelling in influencing our thoughts, emotions, and behaviours. In his later work, he explored how we exert control over the events that impact our lives. **Learning by Observing** Albert Bandura's theories highlight the importance of cognition (thinking) and observational learning (modelling) in human behaviour. His social-cognitive theory proposes that behaviours, including phobias, can be learned vicariously by observing others' actions and the subsequent consequences, whether they be reinforcement or punishment. This type of learning, known as observational learning or modelling, is involved in a broad spectrum of behaviours. For instance, children learn to hit by observing others in real life and on television, while adults acquire job skills by observing or being shown by others. Bandura's theories hold more influence among developmental psychologists compared to conditioning theorists, as he argues that learning does not always necessitate reinforcement. (Based on Bandura, 1977a, 1982, 1989, 2001). What an individual learns from observing others is influenced by factors such as attention and memory. Maturation also plays a crucial role; for instance, a 4-year-old is unlikely to learn geometry by watching a high-school-aged sibling do homework. Bandura further proposes that an observer's learning from a specific model is shaped by their personal goals, expectations of potential outcomes if they adopt the model's behaviour, and self-assessments of their performance. **Reciprocal Determinism** Albert Bandura introduced the concept of **reciprocal determinism**, a human development process based on the interaction of three factors: - **Personal**: This includes cognitive abilities, physical characteristics, beliefs, attitudes, and expectations. - **Behavioural**: This encompasses physical-motor and verbal actions. - **Environmental**: This involves other people and physical surroundings. Bandura's model of reciprocal determinism forms a triangle of bidirectional influence, suggesting that we are not only shaped by our circumstances but also have the ability to influence our situation. This influence, in turn, affects our expectations about our control over future events, a process referred to as coevolution. In the context of children, they are actively engaged in molding the environments that subsequently influence their behaviour and personality development. (Based on Bandura, 1977a, 1986, 2001, 2006) **Self-Efficacy** Albert Bandura (1997a, 1997b) emphasized the concept of **self-efficacy** in relation to personal factors. Self-efficacy refers to an individual's belief in their own ability to bring about a desired outcome. Individuals with high self-efficacy have greater expectations for success and exhibit more effort and persistence when facing challenges. On the other hand, those with low self-efficacy have lower expectations for success and are more likely to acquiesce or avoid difficult tasks. **Systems Theory** The systems approach to human development considers the dynamic interaction between personal and external factors. Personal factors can include biophysical, spiritual, intellectual, emotional, behavioural, and interpersonal aspects, while external factors typically encompass the physical environment and social and cultural influences. A key principle of systems theory is holism, which asserts that the "whole" is primary and exceeds the sum of its parts. For instance, a loaf of bread is more than just its ingredients: wheat flour, yeast, and water. The ingredients - wheat flour, yeast, and water - each have their own properties. However, when they are combined and processed (mixed, kneaded, and baked), they interact and transform into something entirely new - a loaf of bread. This loaf of bread has characteristics and functionalities (like the ability to be used for a sandwich) that none of the individual ingredients possess on their own. A person's development is influenced by changes in any part of this dynamic system. Growth is seen as a reorganization of the system in response to change. If the adjustment is adaptive, it fosters a high level of holistic health, termed wellness. Conversely, maladaptive adjustments can result in disorder or dysfunction. **Bronfenbrenner's Bioecological Systems Theory** Urie Bronfenbrenner's bioecological systems theory is a notable systems approach that explains development based on the relationships between individuals and their environments, or interconnected contexts. This theory also considers the passage of time, termed the "chronosystem". Bronfenbrenner aimed to categorize the individual and contextual variables influencing development and to detail their interactions. (Based on Bronfenbrenner, 1979, 2005) **Macrosystem** ![](media/image6.png)Bronfenbrenner's theory describes the contexts of development as spheres within spheres. The outermost sphere, known as the **macrosystem**, represents the sociocultural context. This macrosystem embodies the prevailing sociocultural ideologies, values, beliefs, and the organization of social systems and public policies through macro institutions, such as the federal government. These elements shape the environment in which a child grows up. For instance, the cultural context includes Canadians' beliefs about the significance of education. **Exosystem** The next sphere in Bronfenbrenner's theory is the **exosystem**, which represents the socioeconomic context. This includes cultural institutions that indirectly influence a child's development, such as a parent's workplace, social services, and healthcare and educational systems. For instance, while the funding for education exists within this socioeconomic context, the ability to provide universal education may be constrained by the nation's wealth, despite a strong societal belief in the importance of education. **Microsystem** The **microsystem**, in Bronfenbrenner's theory, refers to the immediate context that includes direct exposures such as family, school, religious institutions, and neighbourhoods. The **mesosystem** represents the interconnections between these components. For instance, a child's specific school and family form part of the microsystem, while the parents' involvement in the school and the school's response constitute the mesosystem. Although a child's culture may highly value education and the nation's economy may sufficiently fund schooling, the child's education is more profoundly influenced by the specific school they attend and the connections (or lack thereof) between the school and their family. Therefore, a child's immediate context (microsystem and mesosystem) could either align with or contradict the broader cultural and socioeconomic contexts. **The Person** A child's development is also significantly influenced by their individual context, which includes their genetic makeup and developmental stage. For instance, a student who hasn't yet mastered reading skills may not benefit from an advanced literature program. Therefore, even if the child's culture, socioeconomic situation, school, and family are all oriented towards providing a quality education, the child's ability to benefit from it ultimately depends on how well the education aligns with their individual needs. **Ecobiodevelopmental Theory** Recent developments are building on earlier systems theories of development, such as Bronfenbrenner's bioecological model. Developmentalist Jack P. Shonkoff from Harvard University, along with others, are promoting the systems approach to become more mainstream. They encourage stakeholders, including policy makers, practitioners, and parents, to adopt a more interdisciplinary approach to human development. Their efforts significantly influenced the American Academy of Pediatrics' (AAP) endorsement of an interdisciplinary, science-based approach to national early childhood policy and practice. The AAP now supports an ecobiodevelopmental (EBD) framework for designing, testing, and refining early childhood interventions, specifically targeting health promotion and disease prevention. The AAP is urging its members to become leaders and advocates for national social change, a sentiment echoed by Canadian health organizations and the World Health Organization's global efforts. The new Ecobiodevelopmental (EBD) framework for research, policy, and programs is informed by a growing body of evidence. This evidence suggests that the foundations of healthy development, as well as the origins of many impairments and susceptibilities to diseases and mental disorders, can be biologically embedded through interactions between epigenetics and the environment. These interactions begin even before conception and continue throughout early life and can have effects across generations. The implication is that the most cost-effective way to improve health, both nationally and globally, is to focus efforts on, and intervene during, the prenatal and early childhood periods of development. These efforts may include forming and implementing policies and strategies that reduce the disruptive effects of prolonged and intense adversity in early childhood, a phenomenon now referred to as toxic stress. This can range from nutritional deficiencies to maltreatment. **Comparing Theories** **Overview of Human Development Theories** **Theory** **Main Idea** **Strengths** **Weaknesses** ------------------------------------------ -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- **Biological** Biological and physiological processes (e.g., those involving genes, hormones, and neurotransmitters) influence traits and behaviours. Biological principles that underlie genetics and epigenetics expand understanding of human health and disease processes and uncovering the role that inheritance plays in human health and the related importance of early intervention. Biological approaches may neglect the impact of psychological factors, sociocultural factors, and family conditions on development. Genetic It emphasizes the genetic origins of human behaviour. Relevant to many fields, from molecular medicine to a better understanding of human evolution, this has contributed to advances in medicine and biotechnology. It poses ethical issues around gene patents, genetic testing, discrimination, privacy, genetic modification; our genetic makeup accounts for only a portion of human traits. Epigenetic The environment and life experiences have immediate and long-term influences on gene expression, the genetic code, and, by extension, human behaviour, and health. It contributes to our understanding of the inheritance factors involved in vulnerability and resilience to disease and disorder; it focuses attention on the need to promote early interventional strategies during prenatal and early childhood development. The precise, underlying mechanisms by which the environment and life experiences can alter epigenetic markings remain largely unknown. Evolutionary The genetic makeup of populations changes over generations by favouring traits that enable individuals to survive and reproduce. It focuses attention on the importance of early-life influences on later behaviour and health outcomes. It underestimates the impact of the environment and places too much emphasis on heredity; the theories are difficult to prove. **Psychoanalytic** Adult behaviour and feelings, including psychological problems, stem from our childhood experiences. This highlights the important role that parenting has on early childhood experiences; it proposes that the child's needs change with age, so parents and other caregivers must constantly adapt to the changing child. Many psychoanalytic concepts were derived from individual case studies and cannot be readily applied universally; the concepts are difficult to test empirically (e.g., how to objectively measure internal drives and emotions). Freud's Psychosexual Theory Personality develops in five stages from birth to adolescence; in each stage, the need for physical pleasure is focused on a different part of the body. This emphasizes the importance of experiences in infancy and early childhood; provides psychological explanations for mental disorders; and has given psychologists several helpful concepts, such as the unconscious, the ego, and defence mechanisms. Sexual feelings are not as important in personality development as Freud claimed; concepts, such as libido and psychosexual, are more descriptive than scientific in nature. Erikson's Psychosocial Theory Personality develops through eight life crises across the entire lifespan; a person finishes each crisis with either a good or a poor resolution. This helps explain the role of culture in personality development; it is important in lifespan psychology and provides a useful description of personality development at different ages. Describing each period in terms of a single crisis is probably an oversimplification. **Humanistic** This emphasizes the basic goodness of human beings; everyone has a unique potential and has an inborn drive for personal growth and achieving self-actualization. It shifts the focus of development onto individual choices more so than emotional, biological, or societal forces; it is inherently optimistic and gives people more credit in controlling and determining their well-being. The concepts are difficult to test empirically because the propositions are not stated clearly enough (e.g., how to objectively measure self-actualization). Maslow's Theory of Motivation One is motivated to satisfy a range of physical, social, and psychological needs; the ultimate goal in life is to achieve self-actualization. It focuses attention on healthy development. The terms and hierarchical ranking of Maslow's list of needs are unproven. Rogers's Theory of the Self This emphasizes the individual's responsibility for, and the active role one plays in, furthering one's personal growth. The individual can effect change toward personal growth. It tends to discount the importance of past events. **Behavioural** Behaviour is determined by the environment through conditioning; behaviourism is primarily concerned with observable behaviour, as opposed to internal mental events such as thinking; empirical data is collected through careful and controlled observation and measurement. Learning theories can explain both consistency and changes in behaviour; it is optimistic about the possibility of change---behaviour can change if the reinforcement system changes, so problem behaviours can be modified; it provides an accurate picture of the way in which many behaviours are learned. The traditional learning theorists' approach is not developmental; it doesn't tell us much about change over a lifespan, in either childhood or adulthood. Pavlov's Classical Conditioning Learning happens when neutral stimuli become so strongly associated with natural stimuli that they elicit the same response. It is useful in explaining how emotional responses, such as phobias, are learned. The explanation of behavioural change is too limited to serve as a comprehensive theory of human development. Skinner's Operant Conditioning Theory Development involves behaviour changes that are shaped by reinforcement and punishment. This is the basis of many useful strategies for managing and changing human behaviour. Humans are not as passive as Skinner claimed; the theory ignores hereditary, cognitive, emotional, and social factors in development. **Cognitive** Behaviour can be largely explained in terms of how the mind operates (e.g., memory, thinking, and problem-solving processes occur between stimulus and response). The science of cognitive psychology is based mainly on laboratory experiments; it has contributed to many effective therapeutic interventions. Much research involves artificial laboratory tasks, such as learning lists of words, and therefore it doesn't always fully describe how the mind works in the real world. Piaget's Theory of Cognitive Development Reasoning develops in four universal stages from birth through adolescence; in each stage, the child builds a different kind of scheme. This helps explain how children of different ages think about and act on the world. Piaget was inexact about some of the ages at which children develop particular skills; the stage concept may cause adults to underestimate children's reasoning abilities; there may be additional stages in adulthood. Information-Processing Theory Human cognitive functioning---encoding, storage, and retrieval processes---changes with brain maturation and practice, causing changes in cognitive functioning. This helps explain how much information people of different ages can manage at one time and how they process it; it provides a useful framework for studying individual differences in people of the same age. Human information processing is much more complex than that of a computer; the theory doesn't provide an overall picture of development. Vygotsky's Sociocultural Theory Cognitive development is strengthened through social interactions that involve speaking during guided problem-solving tasks. It stresses the importance of sociocultural interaction for cognitive development. Verbal instructions may not benefit cognitive development in some cultures. Bandura's Social-Cognitive Theory People learn from models, and what is learned depends on how they interpret the situation; a child's level of cognitive development affects his or her impressions and reactions to circumstances; we both shape and are shaped by our environment. This helps explain how models influence behaviour; it adds further to our understanding of human development by integrating cognitive, emotional, social, and environmental factors. It does not provide an overall picture of development---biological influences are underemphasized. **Systems** This provides an interdisciplinary perspective to the study of human development; both humans and their environments are active in the developmental process. It captures the complexity of individual and contextual variables and the interactions among these variables. It is hard to form generalizations and predictions because of the complexity of interactions among variables. Bronfenbrenner's Bioecological Theory Human development is a product of individual and contextual variables interacting over time. This highlights the need for research examining the complex interactions among individual and contextual variables. It underplays physical environmental influences (ranging from pollution to poor nutrition or disease). Shonkoff's Ecobiodevelopmental Theory There is a need for a science-based approach toward creating early childhood policies, practices, and interventions aimed specifically at health promotion and disease prevention. It promotes advocacy across all levels of the socioeconomic and political spectrums, with health care professionals taking on a lead role. Determining causal links among developmental variables raises research methodological and ethical challenges. **Development in the Real World** **Transgenerational Impacts of Colonization in Canada** Canadians are increasingly recognizing the damage caused by efforts to assimilate Indigenous peoples into Euro-Canadian culture. From 1880 to 1996, the government ran residential schools to assimilate Indigenous children, leading to negative experiences such as isolation, suppression of traditional language and practices, abuse, malnourishment, exposure to death and disease, and largely inadequate education and vocational training. These experiences have contributed to ongoing transgenerational adversities among Indigenous peoples. Two significant traumatic events for First Nations children and their parents were the residential school experience and the "Sixties Scoop"---the removal of First Nations children for adoption into mostly non-Indigenous families by provincial child protection services. Kevin Berube (2018), director of the Mental Health and Addictions Program at the Sioux Lookout Meno Ya Win Health Centre, provides a vivid illustration of the trauma experienced by Indigenous peoples. He asks us to imagine the horror of strangers, accompanied by a police officer and speaking a different language, arriving at your door to take your children away. The uncertainty, fear, and helplessness of this situation encapsulate the deep intergenerational trauma still experienced by First Nations. (Source: Berube, K. (2018, May 12). The intergenerational trauma of First Nations still runs deep. The Globe and Mail.) Child apprehension policies have inflicted significant emotional harm on Indigenous children, their parents, and subsequent generations. The trauma of forced separation from family, community, and culture has led to a cycle of hardship, worsening life conditions, and diminished resilience, fueled by self-defeating behaviors and experiences of discrimination. The healing process begins with acknowledging the problem's scope. While individual responsibility is often emphasized in Canada, some issues span multiple contexts and require multi-level interventions. Sociopolitical decisions can contribute to societal problems, and changes at this level are necessary to address these issues. To improve the lives of future Indigenous generations, a continuum of care is needed for those currently experiencing intergenerational trauma. This involves focusing on preconceptual health and early childhood health, offering psychosocial, cognitive-behavioral, and medical interventions, and improving living conditions and social and economic resources. Care, support, and interventions must be provided in a timely, culturally appropriate manner by care providers who demonstrate Indigenous cultural awareness and have the support of traditional healers and elders. Programs like the Aboriginal Prenatal Wellness Program in Wetaskiwin, Alberta, which provides culturally safe, client-centered prenatal care, are showing promising results. At the macrosystem level, amends for historical policies that caused harm and support for health and social policies that reduce future risk are crucial. In 2008, Prime Minister Stephen Harper apologized on behalf of the Government of Canada to all former students at residential schools, recognizing the lasting impact these schools had on Indigenous culture, heritage, and language. This apology, along with the Indian Residential Schools Settlement Agreement and the Truth and Reconciliation Commission, has increased awareness of the historical issues contributing to the current challenges faced by Indigenous Canadians. At the individual level, evidence suggests that epigenetics plays a role in the intergenerational transmission of trauma effects. Emotional trauma can cause epigenetic modifications that can be transmitted to future generations. While research into this in humans is just beginning, studies have highlighted the role of lifestyle, life experiences, and environmental factors in changing the epigenome over generations. Current knowledge suggests that interventions at the parental level can prevent or reverse the transmission of intergenerational trauma influences. The epigenome might reset when environmental insults are no longer present or when we adapt to environmental challenges in a new way. This doesn't imply that epigenetic changes alone cause the intergenerational continuity of disadvantage, but identifying a biological component of these complex mechanisms may allow interventions to target and be measured at multiple levels. **List of Key Terms** **Accommodation:** changing a scheme because of some new information. **Assimilation:** the process of using schemes to make sense of events or experiences. **Behaviourism:** the view that defines development in terms of behaviour changes caused by environmental influences. **behaviour genetics:** the study of the role of heredity in individual differences. **behavioural epigenetics:** the study of how the environment and personal behaviour can cause epigenetic changes that affect gene expression, resulting in changes to behaviour and psychological processes over the course of a life and across generations. **bioecological systems theory**: Bronfenbrenner's theory that explains development in terms of the relationships among individuals and their environments, or interconnected contexts. **Chromosomes**: strings of genetic material in the nuclei of cells. **classical conditioning**: learning that results from the association of stimuli. **cognitive theories**: theories that emphasize mental processes in development, such as logic and memory. **defence mechanisms:** strategies for reducing anxiety, such as repression, denial, or projection, proposed by Freud. **deoxyribonucleic acid (DNA)**: a chemical material that makes up chromosomes and genes. **dominant-recessive pattern:** a pattern of inheritance in which a single dominant gene influences a person's phenotype, but two recessive genes are necessary to produce an associated trait. **Ego**: according to Freud, the thinking element of personality. **Epigenetics:** the study of the gene regulation patterns that alter gene function (phenotype) without changing gene structure (genotype). **epigenetic factors:** inheritable and acquired gene regulation patterns that alter gene function (phenotype) without changing gene structure (genotype). **Epigenome:** the sum of inherited and acquired molecular modifications to the genome that leads to changes in gene regulation without changing the DNA sequence of the genome. **esteem need**: the need for a person to have a sense of value and acceptance based, in part, on their experience of respect and admiration from others and on their perceived self-confidence and self-worth. **Equilibration**: the process of balancing assimilation and accommodation to create schemes that fit the environment. **Ethology**: a perspective on development that emphasizes genetically determined survival behaviours presumed to have evolved through natural selection. **evolutionary developmental psychology**: characteristics that promote survival and adaptation appear at different times across the lifespan. **evolutionary psychology**: the view that genetically inherited cognitive and social traits have evolved through natural selection. **Extinction**: the gradual elimination of a behaviour through repeated nonreinforcement. **Genes**: complex chemical units of a chromosome that control or influence inherited traits. **gene expression**: when a gene sequence is activated ("turned on") and ready to be translated into gene products---proteins, for the most part. **gene silencing**: when a gene sequence is made inactive ("turned off") and is prevented from being translated into gene products----proteins, for the most part. **Genome**: all the DNA that an organism possesses. **Genotype**: an individual's unique genetic blueprint. **Holism**: the view that the whole is greater than the sum of its parts. **human epigenomics**: the study of the human epigenome, including the location of all acquired and inherited epigenetic markers, their function, and their role in human physical and mental health. **human genomics**: the study of the human genome, including the location of genes, their function, and their role in human physical and mental health. **Id**: in Freud's theory, the part of the personality that comprises a person's basic sexual and aggressive impulses; it contains the libido and motivates a person to seek pleasure and avoid pain. **information-processing theory**: theoretical perspectives that use the computer as a model to explain how the mind manages information. **learning theories**: theories that assert that development results from an accumulation of experiences. **Libido**: in Freud's theory, an instinctual drive for physical pleasure that is present at birth and forms the motivating force behind virtually all human behaviour. **mitochondrial inheritance**: a pattern of inheritance in which a cell's mitochondrial DNA (mtDNA) is inherited from the mother's egg and not the father's sperm. **Motives**: internal factors or conditions that tend to initiate, direct, or sustain behaviour. **Multifactorial inheritance**: a pattern of inheritance affected both by genes and by the environment. **neo-Piagetian theory**: an approach that uses information-processing principles to explain the developmental stages identified by Piaget. **observational learning, or modelling**: learning that results from seeing a model reinforced or punished for a behaviour. **operant conditioning**: learning to repeat or stop behaviours because of their consequences. **Phenotype**: an individual's whole set of observable characteristics. **predictive-adaptive responses**: the prenate's ability to use information about the current environment to adjust its physiology in anticipation that it will match future environmental conditions and optimize the chances to survive and reproduce in adulthood. **Proteins**: organic compounds, consisting of amino acids, that perform most life functions and make up most cellular structures. **protein-coding genes**: genes that direct the production of proteins. **psychoanalytic theories**: theories proposing that developmental change happens because of the influence of internal drives and emotions on behaviour. **psychosexual stages**: Freud's five stages of personality development through which children move in a fixed sequence determined by maturation; the libido is centred on a different body part in each stage. **Punishment**: any immediate consequence that follows a behaviour and decreases the likelihood that the behaviour will be repeated. **reciprocal determinism**: a process of human development based on the interaction of personal, behavioural, and environmental factors. **Reinforcement**: any immediate consequence that follows a behaviour and increases the likelihood that the behaviour will be repeated. **self-actualization**: the process of fulfilling one's unique personal potential. **Scaffolding**: a process in which the learning of new cognitive skills is guided by someone who is more skilled. **Scheme**: in Piaget's theory, an internal cognitive structure that provides an individual with a procedure to follow in a specific circumstance. **self-efficacy**: the belief in one's own capacity to cause an intended event to occur or to perform a task. **Shaping**: the reinforcement of intermediate steps until an individual learns a complex behaviour. **sociocultural theory**: Vygotsky's view that complex forms of thinking have their origins in social interactions rather than in an individual's private explorations. **Superego**: Freud's term for the part of personality that is the moral judge. **systems approach:** the view that personal factors together with external factors form a dynamic integrated system. **Wellness:** a measure of optimal holistic health. **zone of proximal development**: signifies tasks that are too hard for a child to do alone but that can be managed with guidance.

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