Lesson 26-28

26.1: PRENATAL DEVELOPMENT ▶ LISTEN

The process of human development begins long before we take our first breath. From the moment of conception to birth, a growing baby goes through several distinct stages. For AP Psychology, we’ll focus on the ways prenatal development can impact us later in life.

Prenatal development begins at conception, when a sperm fertilizes an egg to form a single cell called a zygote, containing a complete set of chromosomes from both parents. During the germinal stage, which lasts about two weeks, the zygote undergoes rapid cell division, forming a cluster of cells called a blastocyst that implants into the uterine wall. This stage also includes the possibility of twins, leading to the distinction between fraternal and identical twins.

Monozygotic twins, often referred to as identical twins, occur when a single zygote splits into two separate embryos. This happens early in development, and the resulting twins share the same genetic material. They will always be of the same gender because they share identical DNA.  Also, because of their shared DNA, they often share many personality traits.

Dizygotic twins, also known as fraternal twins, occur when two separate eggs are fertilized by two different sperm. They are no more genetically similar than any other siblings. Fraternal twins can have different physical characteristics and may develop different personalities due to their distinct genetic makeup.  Because they are simply siblings born at the same time, fraternal twins can also be of opposite genders.

Following the germinal stage, the embryonic stage spans from the third to the eighth week of pregnancy, during which the developing baby, now called an embryo, begins forming major organs and body systems, becoming more recognizable as human. From the ninth week until birth, the fetal stage focuses on rapid growth, organ refinement, and increased responsiveness to external stimuli. The development of critical organs and especially the brain highlight the importance of prenatal care.

Prenatal care involves regular medical check-ups, screenings, and education about proper nutrition, exercise, and lifestyle choices. Prenatal care helps identify and address any potential complications, ensuring the best possible outcome for both mother and baby.

While a mother is pregnant, there are many foods, chemicals and even situations that she should avoid to protect her growing child. Teratogens is the name given to any external factor that can disrupt normal prenatal development and have a negative impact on the developing fetus. Examples of teratogens include exposure to alcohol, tobacco smoke, certain medications, or infections. Even extreme heat is a teratogen which is why hot tubs have signs warning pregnant women not to use them. These substances or factors can interfere with the proper formation and functioning of organs and body systems, potentially leading to lifelong consequences for the individual.

A mother’s health plays a critical role in prenatal development, as certain illnesses can have serious effects on a developing baby. For example, infections like rubella (German measles), if contracted during pregnancy, can result in congenital disabilities such as hearing loss or heart defects. Similarly, untreated conditions like diabetes or hypertension can lead to complications such as preterm birth or low birth weight. Some illnesses can also cross the placenta, directly impacting the fetus. For instance, infections like toxoplasmosis or Zika virus can cause severe neurological damage. Regular prenatal care and vaccinations are essential to reduce the risk of maternal illnesses affecting the baby’s development.

Genetic mutations, which are changes in the DNA sequence, can occur spontaneously or be inherited from a parent. These mutations may impact the developing fetus in various ways, depending on the gene or chromosome involved. Some mutations result in conditions like Down syndrome, which occurs when there is an extra copy of chromosome 21. Others might cause rare genetic disorders such as cystic fibrosis or sickle cell anemia. Advances in genetic testing during pregnancy, such as amniocentesis or chorionic villus sampling (CVS), can help identify potential mutations early, allowing families and medical professionals to prepare for any necessary interventions.

Hormonal changes during pregnancy not only support the mother’s body in sustaining a healthy pregnancy but also significantly impact the baby’s development. Hormones like human chorionic gonadotropin (hCG) and progesterone ensure the proper functioning of the placenta and maintain the uterine environment. However, imbalances in maternal hormones can create challenges. For example, thyroid hormone deficiencies during pregnancy may affect the baby’s brain development, potentially leading to cognitive delays. 

Environmental factors, both physical and psychological, can influence prenatal development. A mother’s exposure to pollutants like lead, mercury, or pesticides can disrupt the formation of critical systems, potentially leading to developmental delays or learning disabilities. Additionally, a mother’s emotional environment, such as experiencing high levels of stress or trauma, can impact the fetus. Chronic stress during pregnancy can elevate cortisol levels, which may affect the baby’s brain development and increase the risk of emotional or behavioral issues later in life. Creating a healthy environment, both physically and emotionally, helps set the foundation for a baby’s well-being.

26.2: INFANCY ▶ LISTEN

From the moment of birth, babies possess a remarkable array of innate reflexes and basic motor abilities. However, as they grow, their motor skills evolve and become more refined. Next, we will delve into the motor skills babies are born with and the abilities they acquire as they progress through infancy. 

Newborn reflexes are automatic responses that infants exhibit in response to specific stimuli. These reflexes are present at birth and are crucial for the survival and protection of the newborn. For example, the rooting reflex prompts a baby to turn their head and open their mouth when touched near the cheek, aiding in breastfeeding. 

Sucking is one of the earliest motor skills babies develop. The ability to suck is essential since it enables infants to obtain nourishment through breastfeeding or bottle-feeding. This reflexive action is present from birth and is essential for their survival. As they grow, babies learn to coordinate their sucking pattern and gain control over this motor skill.

Grasping refers to the ability to hold onto objects using the hand and fingers. Initially, babies exhibit a palmar grasp reflex, where objects placed in their palms trigger an automatic grip. As they progress, they develop a voluntary grasp that allows them to intentionally reach out and grab objects. This evolution in motor skills demonstrates their increasing control and coordination.

The rooting reflex is a vital motor skill in newborns that assists in finding nourishment. When the baby's cheek is stroked, they instinctively turn their head toward the stimulus and open their mouth. This reflex helps babies locate the mother's breast or a bottle for feeding. As they grow, this reflex diminishes, eventually being replaced by voluntary head movements.

The startle or Moro reflex is a protective response triggered by a sudden noise or movement. When infants experience a startling stimulus, they react by rapidly spreading out their arms and legs and then pulling them back in. This reflex is believed to be an evolutionary adaptation that helps infants grasp onto their caregiver for protection. Over time, as their nervous system matures, this reflex becomes less pronounced.

The Babinski reflex is characterized by the fanning out and upward curling of the toes in response to the sole of the foot being stroked. This reflex is an indicator of the immaturity of the baby's nervous system. Over time, as the nervous system develops, the Babinski reflex disappears, and the baby gains voluntary control over their foot movements.

Motor development is divided into two categories: gross and fine motor skills. Gross motor skills involve large muscle groups and whole-body movements like crawling, walking, jumping, and balancing. These skills focus on strength and coordination. In contrast, fine motor skills use small muscles, especially in the hands and fingers, to perform precise tasks such as grasping toys, picking up objects, and self-feeding. While gross motor skills help babies navigate their environment, fine motor skills are crucial for activities like writing, drawing, and buttoning clothes as they grow. Together, these abilities form the foundation for physical independence and daily life activities.

Many parents and caretakers watch the development of gross motor skills carefully to monitor on-time development.  Here are key milestones in gross motor development during the first year of life:

Lifting the Head: One of the earliest motor milestones, lifting the head requires the development of neck muscles. Infants gradually gain the strength to lift their heads while lying on their stomachs, which is an essential precursor to other advancements.

Rolling Over: Around 4 to 6 months, infants typically learn to roll over, allowing them to explore their environment and expand their range of movement. This milestone is a result of improved muscle coordination and control.

Sitting Up with Support: Between 6 and 8 months, infants can sit up with support, relying on their arm and core muscles. This achievement provides a stable base for further motor development and facilitates engagement with toys and interaction with caregivers.

Sitting Up without Support: Around 8 to 10 months, infants gain the ability to sit up without any external support. This milestone signifies enhanced strength and postural control, allowing infants to actively participate in their surroundings.

Crawling: Crawling, typically occurring around 8 to 12 months, involves coordinated movements of the arms and legs, strengthening the muscles necessary for more complex motor skills. Crawling enables infants to explore their environment, fostering cognitive and perceptual development.

Walking: Walking, a monumental milestone, emerges between 9 and 15 months. It involves integrating balance, coordination, and muscle strength, enabling infants to navigate their surroundings independently. Walking signifies the culmination of various motor skills acquired throughout infancy.

As babies develop motor skills that allow them to explore their surroundings, their ability to perceive and interact with the environment also matures. One critical aspect of this is visual depth perception—the ability to judge distances and identify potential dangers. While motor development helps babies physically navigate their world, depth perception ensures they do so safely. Understanding how infants perceive depth provides insight into how their sensory and motor skills work together to support exploration and learning. 

The Visual Cliff Experiment is a study in psychology that helps us understand how babies perceive depth and danger. Scientists created a special table with a glass top.  Under the glass on one side of the table is a checkerboard, but not on the other. When babies who can crawl or walk are put on this glass surface, they usually hesitate or act scared when they see the "cliff," even though there's no real danger. This experiment shows that even very young babies have an inborn sense of depth and can tell when something looks risky, which helps them avoid dangers like falling.

26.3: ADOLESCENCE ▶ LISTEN

Adolescence is a developmental stage that bridges the gap between childhood and adulthood and it is a period of significant transformation, not only in terms of height and weight gain but also through a myriad of other physical changes. These changes are crucial markers of development, shaping the transition from childhood to adulthood. 

The adolescent growth spurt is one of the most noticeable physical changes during this stage of development. This rapid increase in height and weight typically begins earlier in girls, around ages 9 to 11, and later in boys, around ages 11 to 13. Driven by hormones like growth hormone and sex hormones (estrogen in girls and testosterone in boys), this spurt leads to the elongation of bones, an increase in muscle mass, and changes in body composition. It’s during this time that adolescents may experience "growing pains" and outgrow their clothes seemingly overnight. This dramatic physical growth is a key part of preparing the body for adulthood. 

Puberty is a key milestone during adolescence, marked by the activation of the reproductive system. The hypothalamus releases gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gland to produce luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormones trigger the development of primary and secondary sexual characteristics.  Naturally, scientists have developed specific names for these changes.  Adrenarche refers to the maturation of the adrenal glands, leading to the increased production of androgen hormones, such as DHEA. These hormones play a role in the development of secondary sexual characteristics, including the growth of pubic and underarm hair. Gonadarche, on the other hand, refers to the maturation of the gonads (testes in males and ovaries in females), leading to the production of sex hormones.

Puberty is the time period when the reproductive system develops, but along with the reproductive organs, adolescents also develop other physical characteristics which correspond to their sexual development.  For example, boy’s voices tend to deepen.  The pitch of a person’s voice has nothing to do with sexual reproduction, so we can classify these different types of developments into two categories. Primary sexual characteristics are the physical features directly related to reproduction. In males, this includes the development of the testes and the ability to produce sperm. In females, it involves the development of the ovaries and the onset of menstruation. Secondary sexual characteristics, however, are non-reproductive physical traits that distinguish males and females, such as breast development in females and facial hair growth or voice changes in males.

Menarche refers to the onset of menstruation in females, indicating the ability to conceive. Spermarche, on the other hand, refers to the first ejaculation of sperm in males, marking their fertility. Both menarche and spermarche are important milestones in the reproductive development of adolescents.  While we are focused mostly on physical development in this lesson, it’s important to note that these two physical milestones are important in many cultures, often marked by specific celebrations or rituals.

During adolescence, the frontal lobes of the brain, responsible for executive functions such as decision-making and impulse control, undergo significant development. This process, known as frontal lobe maturation, continues into early adulthood. It’s important for high school students to remember that while their bodies may have fully developed, the decision making areas of their brains are still a work in progress!

26.4: LATE ADULTHOOD ▶ LISTEN

Late adulthood, typically beginning around age 65, is marked by a range of physical, cognitive, and emotional changes as individuals navigate the final stage of the human lifespan. While aging is inevitable, the experience of late adulthood varies widely depending on genetics, lifestyle, and environmental factors. This stage is often characterized by both challenges and opportunities for growth and reflection.  

As the body ages, a number of physical changes become apparent. Reproductive ability significantly declines, with women experiencing menopause, usually between the ages of 45 and 55. Menopause marks the end of menstrual cycles and fertility and is accompanied by symptoms such as hot flashes, sleep disturbances, and mood changes due to fluctuating hormone levels. For men, while fertility may persist, testosterone levels often decline gradually, which can affect energy levels and physical performance.  

Mobility and flexibility also diminish with age. Joints may become stiffer, muscles weaker, and reaction times slower, which can affect daily activities and increase the risk of falls. To maintain mobility, many older adults incorporate physical activity into their routines, such as yoga, walking, or resistance training, to combat these effects.  

Sensory abilities also show noticeable declines in late adulthood. Visual acuity is often affected by conditions such as cataracts or macular degeneration, which can impair reading and driving. Similarly, auditory acuity declines, especially in higher frequency ranges, leading to difficulties in communication. Assistive technologies like glasses and hearing aids can mitigate these sensory declines, helping older adults maintain independence.  

Cognitive development in late adulthood is a mixed picture, with some areas of cognition declining while others remain stable or even improve. Fluid intelligence, which refers to problem-solving and the ability to think quickly, tends to decline as individuals age. This decline may manifest as slower processing speeds or difficulties with tasks that require multitasking or rapid decision-making.  

In contrast, crystallized intelligence, which encompasses accumulated knowledge and skills, often remains stable or even improves. Older adults often draw upon their lifetime of experiences and wisdom, excelling in tasks that require expertise, judgment, and cultural knowledge. For example, an older adult may compensate for slower processing speeds by relying on experience-based problem-solving strategies.  

Dementia is a significant cognitive concern in late adulthood, affecting memory, reasoning, and daily functioning. Alzheimer’s disease is the most common form of dementia and is characterized by the progressive deterioration of brain cells. While not all older adults develop dementia, its prevalence increases with age, highlighting the importance of early detection and support systems for individuals and caregivers.  

Elisabeth Kubler-Ross is a psychologist who has become famous for her study of how people approach loss and the end of life.  She proposed that people who suffer loss or know they are dying transition through five stages.  The first is denial in which they do not want to acknowledge what has happened.  Then, they are angry.  Next, they attempt to make a deal to get out of the situation, often with god.  This stage is called bargaining.  After this inevitably fails, they often fall into depression before finally finding  acceptance. These stages represent the emotional responses individuals may experience when facing their mortality or grieving the loss of a loved one. Understanding these stages can provide comfort and validation during times of loss and help individuals navigate the grieving process.

27.1: PIAGET ▶ LISTEN

Understanding how children develop and grow in terms of their thinking has been a central focus in the field of psychology. Jean Piaget, a renowned psychologist, made significant contributions to this area of study. We’ll begin our study of cognitive development with him and his findings.

Jean Piaget was a Swiss psychologist who dedicated his career to studying child development. He believed that children actively construct their understanding of the world through their experiences and interactions with their environment.

Piaget’s approach to cognitive development emphasizes chronological progression, as he proposed that children move through a predictable sequence of stages, each characterized by distinct cognitive abilities. However, his work also contains thematic elements, as he identified universal themes in how children explore, learn, and adapt to their environment. For example, the themes of problem-solving and logical reasoning emerge across his stages but develop differently as children grow. By examining cognitive development both chronologically (the order of stages) and thematically (the core cognitive skills that develop), Piaget provided a framework that helps us understand not just when children learn but how they do so.

Piaget’s theory highlights the interplay of stability and change in cognitive development. Certain cognitive processes, such as the tendency to organize knowledge into schemas, remain stable throughout life. At the same time, significant change occurs as children’s schemas evolve through the processes of assimilation and accommodation. Stability allows children to build on their previous knowledge, while change ensures that they adapt to new information and experiences. For instance, while a child may initially be egocentric early in life, this trait changes as they grow and begin to understand different perspectives. Piaget believed that this balance between stability and change is essential for cognitive growth.

Piaget’s theory also reflects the influence of both nature and nurture on development. From the perspective of nature, Piaget argued that children are born with an innate drive to explore and make sense of their world. This natural curiosity propels them through the stages of cognitive development. On the nurture side, Piaget emphasized the importance of environmental interactions, such as social relationships and hands-on experiences, in shaping a child’s cognitive abilities. For example, children learn through play, experimentation, and observing others, which demonstrates how their environments nurture their development. The interaction between innate cognitive tendencies (nature) and external influences (nurture) creates a dynamic process of learning and growth.

A key aspect of Piaget’s theory is his belief in discontinuous development, meaning that children progress through distinct and separate stages of cognitive growth. Each stage is qualitatively different from the others, with specific milestones and cognitive abilities defining each one. However, one of the key criticisms of Piaget is that development may actually be continuous, with gradual and incremental changes occurring over time rather than abrupt transitions. Modern research suggests that while some aspects of cognitive development appear stage-like, others, such as language acquisition or problem-solving, may develop more continuously.

One of Piaget's key concepts is assimilation, which refers to the process by which children incorporate new information into their existing mental frameworks. Think of assimilation as adding ingredients to a recipe you already know. For example, a child who has learned that dogs are furry and have four legs may assimilate a new dog breed, such as a Dalmatian, into their existing concept of a dog.

In contrast to assimilation, Piaget introduced the concept of accommodation, which involves modifying or creating new mental frameworks to accommodate new information that does not fit existing schemas. Continuing with the previous example, if the child encounters a hairless dog, they may need to adjust their mental framework to include the possibility of dogs without fur.

Piaget proposed four distinct stages of cognitive development that children progress through as they grow. These stages are sensorimotor, preoperational, concrete operational, and formal operational.

The sensorimotor stage occurs from birth to around two years of age. During this stage, infants learn about the world primarily through their senses and physical actions. They develop object permanence, the understanding that objects continue to exist even when they are not visible. For example, when a child realizes that a toy hidden behind a blanket is still there, they have achieved object permanence.  Before a child has developed object permanence, the game peek-a-boo is endlessly entertaining, but not so much afterward. Another significant concept within the sensorimotor stage is stranger anxiety. This refers to the fear or wariness that infants display when encountering unfamiliar individuals. It is a manifestation of the infant's growing ability to differentiate between familiar and unfamiliar faces.

The preoperational stage, spanning roughly from ages two to seven, is a transformative period in cognitive development where children begin to represent the world with mental symbols. Unlike infants in the sensorimotor stage, who rely heavily on physical interactions with their environment, children in the preoperational stage use mental representations such as images, words, and symbols to understand and communicate about their world. For instance, a child may recognize that the word "dog" represents a specific animal, or that a drawing of a circle can stand for the sun. These mental symbols lay the foundation for language development, which explodes during this stage as children rapidly expand their vocabularies and begin to construct sentences.

Pretend play is one of the most vivid examples of how children use mental symbols in this stage. Pretend play allows children to transform ordinary objects into imaginative ones, such as using a stick as a sword or pretending that a cardboard box is a spaceship. These imaginative activities not only enhance creativity but also help children practice social roles, solve problems, and explore different perspectives in a safe and controlled environment. For example, during a game of "house," a child might pretend to be a parent taking care of a baby, learning about adult responsibilities and nurturing behaviors in the process.

Another hallmark of the preoperational stage is animism, the belief that inanimate objects have thoughts, feelings, or intentions. This is why young children might talk to their stuffed animals as if they are alive or believe that the sun "goes to sleep" at night. Animism reflects the child’s tendency to project human-like qualities onto the world around them, helping them make sense of their environment in a way that aligns with their limited cognitive abilities.

Egocentrism is a key cognitive limitation during the preoperational stage. This term refers to a child’s difficulty in seeing the world from perspectives other than their own. A classic example of egocentrism is Piaget's Three Mountain Task. In this experiment, a child is shown a model of three mountains and asked to describe what someone else would see from a different vantage point. Preoperational children often struggle with this task, assuming that others see exactly what they see. Egocentrism can also be observed in everyday interactions; for instance, a child might cover their eyes during hide-and-seek and assume that because they can’t see others, others can’t see them.

However, as children approach the later years of this stage, they begin developing the foundation for the theory of mind—the understanding that other people have thoughts, feelings, and perspectives that are different from their own. Theory of mind represents a significant cognitive shift, allowing children to understand that others might have beliefs or desires that differ from reality. For example, a child might begin to recognize that their friend doesn’t know what’s inside a wrapped gift, even if the child already does. This emerging ability to understand others’ mental states is crucial for social interactions and relationships.

The concrete operational stage typically occurs from around seven to eleven years of age. Children in this stage demonstrate logical reasoning about concrete objects and events. They acquire the concept of conservation, understanding that the quantity of a substance remains the same even if its appearance changes. An example of conservation is recognizing that pouring the same amount of water from a wide container into a tall, narrow one does not change the amount of water present. Reversibility is closely related to conservation and refers to the understanding that actions can be undone or reversed. In the context of conservation, it means recognizing that the water poured from the tall, narrow container can be poured back into the wide container, restoring the original quantity.  In another example of these concepts, a younger child would see two cookies as the same as one cookie broken in half and not realize that the two partial cookies could be put back together to make just one cookie.

The final stage, the formal operational stage, typically begins around age twelve and continues into adulthood. During this stage, individuals develop the ability to think abstractly and hypothetically. They can engage in deductive reasoning and consider multiple possibilities. For example, a teenager in this stage may contemplate the consequences of different career paths before making a decision.

While Piaget's theories have greatly influenced our understanding of child development, there have been criticisms and new research that challenge some of his ideas. Some argue that children's cognitive development may be more continuous rather than stage-like. Additionally, cultural and environmental factors may influence the rate and extent of cognitive growth.

27.2: VYGOTSKY ▶ LISTEN

Human development is complex and the environment people grow up in plays a pivotal role in shaping an individual's development. Lev Vygotsky, a renowned psychologist, emphasized the impact of the environment on human development. According to Vygotsky, individuals acquire knowledge and skills through social interactions and cultural experiences. He argued that children's cognitive development is closely linked to their social interactions with more knowledgeable others, such as parents, teachers, and peers.

Vygotsky's Sociocultural Theory further expands upon the role of the environment by highlighting the importance of cultural context in development. This theory suggests that individuals are deeply influenced by the cultural values, beliefs, and practices of their society. Here are some examples. Imagine you're a gamer—your skills and strategies aren't just in your head; they come from the gaming community, YouTube tutorials, and maybe even friendly competitions with your friends. Ever notice how your slang or expressions change when you hang out with different groups? That's Sociocultural Theory in action. The way you speak is influenced by the people you talk to and the communities you're part of.  Imagine you're studying for a test. The way you approach it, whether you prefer group study or solo sessions, is influenced by the culture of learning in your school or even your family. The study habits you develop aren't just about you—they're a dance between your personal style and what's considered the norm. The way you present yourself online, the memes you share, or the trends you follow—it's all influenced by the larger online culture. Sociocultural Theory says that even your online identity is a product of the social and cultural forces shaping you.

Another of Vygotsky’s important ideas has to do with learning.  He described an idea called the Zone of Proximal Development (ZPD). The ZPD refers to the gap between an individual's current level of development and their potential level of development with the assistance of a more skilled individual. It represents the zone where learning and cognitive growth occur most effectively.

Like the scaffolding workers put up at a construction site, the ZPD suggests that individuals can reach higher levels of development when provided with appropriate support and guidance. For instance, think of a student learning to solve complex mathematical problems. Initially, they may struggle to solve them independently. However, with the help of a knowledgeable teacher who provides guidance and gradually reduces support, the student can gradually master the skill and solve similar problems on their own. The supports the teacher gives are often called scaffolding, a direct borrowing of the term used in the construction industry. The ZPD illustrates how the environment, in the form of a knowledgeable other, facilitates learning and development.

27.3: FREUD ▶ LISTEN

Sigmund Freud is probably the most famous of all psychologists and he also had theories about development. According to Freud, children progress through five distinct psychosexual stages: oral, anal, phallic, latent, and genital. Each stage is characterized by a focus on a particular erogenous zone and the conflicts that arise during these stages impact an individual's personality development.

The oral stage is the initial phase of psychosexual development, occurring from birth to approximately 18 months. During this stage, the child's primary source of pleasure and satisfaction is through oral activities, such as sucking and biting. The primary conflict in this stage revolves around weaning, as the child learns to cope with the frustration of losing the oral gratification provided by breastfeeding. Failure to resolve this conflict may lead to oral fixations in adulthood, manifesting as behaviors like smoking, overeating, gum chewing, nail biting, thumb sucking, or excessive talking.

The anal stage follows the oral stage and occurs roughly between the ages of 18 months and 3 years. During this phase, the child derives pleasure from controlling and eliminating bodily waste. The primary conflict arises from toilet training, as the child learns to balance societal demands for cleanliness and control over their bodily functions. An excessive emphasis on control or overly strict toilet training may result in anal retentive or anal-expulsive personality traits in adulthood.  In other words, learning to hold it in when your a child, or not learning this, can lead adults to grow up to be the kind of people who can either never let anything go and have to have everything perfect, or let everything go and never care about anything.

The phallic stage emerges around the ages of 3 to 6 years, during which children experience a heightened interest in their genitalia. Freud believed that during this stage, children develop unconscious sexual desires for the opposite-sex parent, known as the Oedipus complex in boys and the Electra complex in girls. The resolution of these desires occurs through identification with the same-sex parent, and learning societal values and moral standards.

The fourth stage, the latent stage, spans from approximately 6 years to the onset of puberty. During this period, sexual impulses are dormant, and children focus on developing social skills, friendships, and expanding their knowledge. Freud considered this stage as a period of relative calm in terms of psychosexual development, allowing the child to consolidate their energy towards education and other social activities.

The final stage, known as the genital stage, begins with the onset of puberty and continues into adulthood. During this stage, the individual's sexual desires reawaken, and they seek gratification through mature sexual relationships. Successful completion of the previous stages is crucial for healthy development in the genital stage, as unresolved conflicts may result in difficulties forming intimate relationships or expressing sexuality.

According to Freud, if a child fails at any of these stages, they may have problems later in life.  This fixation refers to an unresolved conflict or an excessive attachment to a particular psychosexual stage, hindering the individual's progression to the subsequent stages. When a child experiences fixation, they become fixated at that particular stage, leading to lasting influences on their adult personality and behavior. 

Freud's theory of psychosexual stages provides a framework for understanding the complex interplay between biological drives and social influences during childhood development. Although Freud's theory has faced criticism and has mostly been abandoned by psychologists today, it remains a landmark contribution to the field of psychology, stimulating further research and discussion on the development of human beings.

28.1: ELEMENTS OF LANGUAGE ▶ LISTEN

Language, an intricate and fascinating human phenomenon, serves as the foundation of communication and as a unifying force that binds people together. However, have you ever wondered what components all languages share? 

Spoken language is built upon sounds, and linguists call the sounds of a language phonemes. Phonemes are the smallest units of sound in a language. For example, in English, the words "pat" and "bat" differ only in their initial phoneme. The ability to differentiate and produce different phonemes is crucial for language comprehension and production. Studies in psychology have shown that infants possess a remarkable ability to detect and discriminate phonemes from various languages, indicating an innate predisposition for language acquisition.  Over time, your brain becomes attuned to the phonemes of the languages you hear and at some point, you may find it nearly impossible to understand and make phonemes from languages you are unfamiliar with.

By themselves, phonemes usually are meaningless. Most words are made up of more than just one sound or phoneme. Morphemes are the smallest meaningful units of language. Morphemes can be individual words like “cat” or parts of words, such as prefixes, suffixes, and roots. For instance, in the word "unhappiness," "un-" and "-ness" are morphemes that alter the meaning of the root word "happy." By combining morphemes, we can create an infinite number of words and convey subtle nuances in meaning. Understanding morphemes allows us to expand our vocabulary and comprehend the intricacies of language.

Semantics is the study of meaning in language. It examines how words and sentences convey information and how individuals interpret and understand that information. Semantics involves the use of context, connotation, and denotation to derive meaning. For example, the word "cool" can refer to both temperature and social popularity, depending on the context. Understanding semantics enables us to navigate the nuances and subtleties of language, avoiding misunderstandings and miscommunications.

So far, we’ve explored individual sounds, meanings and words, but language, of course, is made up of sentences that combine many words. Grammar refers to the set of rules that govern how words are organized and combined and each language has its own grammar. Grammar rules include both word order and things like punctuation.  Grammar allows us to structure sentences, understand word order, and differentiate between tenses, cases, and other grammatical features. Without grammar, language would lack coherence and clarity, making effective communication impossible.  

While grammar involves both word order and punctuation, syntax is just the rules governing word order in a language. Different languages may have different syntactic rules, influencing the order of subject, verb, and object. For example, in English we usually put adjectives before nouns.  We would say that the teacher drives a red car.  But in other languages the adjective follows the noun.  In Spanish that same red car would be un coche rojo, with red following the car.  If you don’t follow the syntax rules of a language, you run the risk of not being understood, or at the very least, sounding like Yoda.  Study hard, you must!

Students often mix up grammar and syntax.  Think of grammar as a set of rules that helps you use words correctly in a sentence. It covers things like spelling, punctuation, and how to structure sentences. Syntax is just the arrangement of those words in a sentence to make sure it all makes sense. So, grammar is like the overall rulebook, and syntax is how you play by those rules when building sentences.

28.2: STAGES OF LANGUAGE DEVELOPMENT ▶ LISTEN

Language development is one of the most fascinating aspects of human growth. From the earliest coos to complex sentences, children progress through predictable stages as they learn to speak and understand language. By examining these steps, we can better appreciate how children move from simple sounds to sophisticated communication. These stages can be broadly divided into two categories: the time before babies understand that all the sounds they hear the people around them making have meaning, and after they realize that language is a means of communicating  

Even before producing sounds, infants rely on nonverbal cues to communicate their needs and emotions. From birth, babies use eye contact, facial expressions, and gestures to interact with their caregivers. For instance, a baby may cry to signal hunger or smile to express happiness when they see a familiar face. Babies also rely on the facial expressions and nonverbal communication of others to understand things such as permission and danger. This reliance on nonverbal communication demonstrates that the need to connect with others is innate, even before words are understood or spoken.  

Around 6 to 8 weeks of age, babies enter the cooing stage. During this phase, infants produce vowel-like sounds such as “ooo” and “ahh.” Cooing is more than just adorable; it’s a crucial part of language development. It helps babies practice using their vocal cords and begin to experiment with sounds, laying the foundation for more complex vocalizations later. Caregivers often respond to coos with exaggerated speech patterns, reinforcing the infant's attempts to communicate.  

Babbling typically begins between 4 and 6 months and marks a significant step in language development. In this stage, infants start combining consonants and vowels into repetitive syllables, such as “ba-ba” or “da-da.” This stage is important for several reasons: it helps babies develop control over their vocal muscles and introduces them to the rhythm and patterns of speech. While babbling might sound like an attempt at speaking, babies at this stage don’t yet understand the meaning of words. Instead, they are mimicking the sounds and intonations they hear in their environment.  

As children grow, they transition from simply making sounds to understanding and using language meaningfully.  

Around their first birthday, children typically enter the one-word stage, also known as the holophrastic stage. At this point, they begin to associate specific words with objects, people, or actions. For example, a toddler might say “dog” when pointing to a pet or “milk” when expressing hunger. Although they usually only produce one word at a time, these words often carry significant meaning. In this stage, a single word can represent an entire thought—for instance, “up” might mean “pick me up” or “I want to go up.”  

As children’s vocabulary expands, they begin combining words into short sentences, typically between the ages of 18 months and 2 years. This stage is referred to as telegraphic speech because the sentences resemble a telegram, omitting less critical words like “is” or “the.” For example, a child might say “want cookie” instead of “I want a cookie.” During this phase, children start to demonstrate an understanding of basic grammar, such as the proper order of words in a sentence. Telegraphic speech allows children to express more complex ideas and desires as they gain confidence in their language abilities.  

As children begin to understand grammatical rules, they sometimes overapply them, leading to errors in speech. This phenomenon is known as overgeneralization. For instance, a child might say “goed” instead of “went” or “tooths” instead of “teeth” because they are applying regular grammatical patterns (adding -ed or -s) to irregular words. These errors sometimes upset parents who think their children, who previously had used the words “went” and “teeth”, but overgeneralization actually demonstrates that children are learning and experimenting with language rules rather than just mimicking. 

28.3: OTHER LANGUAGE TOPICS ▶ LISTEN

Language is a defining characteristic of human beings, allowing us to communicate complex thoughts, emotions, and ideas. But are we born ready to learn language? What happens if we are deprived of exposure to language during our early years? And do we create words for our thoughts, or do we only think things we have words for?  To close out our study of language we will delve into these intriguing questions, drawing upon key concepts from psychology to shed light on the intricate relationship between language, cognition, and human development.

One thing that linguists have explored is the question of when languages must be learned.  Here, case studies are of particular importance because they help us understand the critical periods in language development. If a child is not exposed to language during these critical periods, it can significantly impact their ability to acquire language later in life. The case of the Wild Boy of Aveyron exemplifies the importance of critical periods in language development.  His real name was Victor and he was found by hunters in France in the 1700s.  Victor had been abandoned but somehow survived on his own in the woods until about the age of 9. Despite attempts to teach him language, Victor struggled to develop linguistic abilities beyond a rudimentary level, emphasizing the importance of early language exposure in shaping our linguistic capabilities.  The concept that the first few years of life are the critical period for learning language are why many language teachers encourage schools to create immersion classes at the elementary level rather than waiting until high school to begin teaching students a second language.

The relationship between language and thought has long been a topic of interest in psychology. Some argue that language shapes our thoughts, while others propose that thought exists independently of language. The Sapir-Whorf Hypothesis, also known as linguistic relativity, suggests that the language we speak influences the way we perceive and think about the world. Linguistic determinism, an extreme form of the hypothesis, contends that language determines our thoughts entirely.  In other words, you can’t have a thought without having the words for it.  Consider how different cultures have unique words for emotions that may not exist in other languages. The absence of a specific word may make it difficult for speakers of that language to articulate and understand that particular emotion, potentially influencing their perception and experience of it.  Another example might be the words used to describe siblings.  For example, in English there is a word “sister” which can describe a sister who is either older or younger than you.  However, in other languages there are specific words for “older sister” and “younger sister” but not just for “sister.”  The theory of linguistic relativity would suggest that people who grow up speaking such a language may have a hard time even imagining the idea of a sister without also including the concept of birth order that way that a native English speaker could. Since language is often rooted in a particular place, some languages have many words to describe certain phenomena, while other languages have no way to describe such things.  In English, for example, we have words for low tide, rising tide, high tide and falling tide. But for speakers of Hawaiian, there are far more terms to describe the variations of the tide. According to linguistic relativism, Hawaiian speakers can able to think about tides in ways English speakers simply can not.