Children typically take their first steps between 9 and 12 months of age, and are typically able to walk independently by around 15 months. At the age of two, children are expected to be able to build a tower of six cubes. Sorting objects into categories is a skill that typically develops around the age of three.

The Emergence of Social Smiling in Infants

Wormann (2014) discusses the emergence of social smiling in infants, which is usually interpreted as the first positive expression directed towards a cause. This occurs when an infant with an initially expressionless face examines the face of another person, and their face and eyes light up while the corners of their mouth pull upward. The age of the first appearance of the social smile varies across cultures, ranging from the fifth to seventh week. Additionally, there are differences in its duration and frequency between the second and seventh month of life. Understanding these milestones is important for a basic understanding of normal child development.

Child Development Milestones:
4 weeks Responds to noise (either by crying, of quieting), follows an object moved in front of eyes
6 weeks Begins social smiling*
3 months Holds head steady on sitting
6 months Rolls from stomach to back, starts babbling
7 months Transfers objects from hand to hand, looks for dropped object
9 months Sits unsupported, begins to crawl
12 months Cruising (walking by holding furniture)
18 months Walks without assistance, speaks about 10-20 words
2 years Runs, climbs up and down stairs alone, makes 2-3 word sentences
3 years Dresses self except for buttons and laces, counts to 10, feeds themself well
4 years Hops on one foot, copies a cross
5 years Copies a triangle, skips

Developmental Stages

There are four main developmental models that are important to understand: Freud’s theory of psychosexual development, Erikson’s theory of psychosocial development, Piaget’s theory of cognitive development, and Kohlberg’s theory of moral development.

Freud’s theory of psychosexual development includes five stages: oral, anal, phallic, latency, and genital. These stages occur from birth to adulthood and are characterized by different areas of focus and pleasure.

Erikson’s theory of psychosocial development includes eight stages, each with a specific crisis to be resolved. These stages occur from infancy to old age and are focused on developing a sense of self and relationships with others.

Piaget’s theory of cognitive development includes four stages: sensorimotor, preoperational, concrete operational, and formal operational. These stages occur from birth to adulthood and are focused on the development of cognitive abilities such as perception, memory, and problem-solving.

Kohlberg’s theory of moral development includes three stages: preconventional, conventional, and postconventional. These stages occur from childhood to adulthood and are focused on the development of moral reasoning and decision-making.

Understanding these developmental models can help individuals better understand themselves and others, as well as provide insight into how to support healthy development at each stage.

Niemann-Pick disease is caused by a deficiency in sphingomyelinase.

Lesch-Nyhan Syndrome: A Rare Genetic Disorder

Lesch-Nyhan syndrome is a rare genetic disorder that causes the overproduction and accumulation of uric acid in the body, leading to various health problems such as gouty arthritis, kidney stones, and subcutaneous tophi. The condition primarily affects males and is caused by mutations in the HPRT gene located on the X-chromosome.

People with Lesch-Nyhan syndrome typically experience motor disability, including severe dystonia, hypotonia, and choreoathetosis, which can make it difficult of impossible for them to walk of sit without assistance. They may also exhibit self-injurious behavior, such as biting and head-banging, which is the most common and distinctive behavioral problem associated with the condition. Intellectual disability is common, but severe cognitive impairment is rare.

The absence of the HPRT enzyme, which is responsible for recycling purine bases, leads to the accumulation of uric acid and affects the development of specific neural pathways in the brain, particularly the mesotelencephalic dopamine pathways. This disruption is likely responsible for the motor disability and behavioral peculiarities associated with the condition.

Treatment for self-injurious behavior typically involves the use of protective restraints applied to the limbs, trunk, of head to prevent self-hitting of self-biting. Dental extraction may be necessary in cases of lip of tongue biting. Behavior modification methods that involve extinction may also be used, but neuroleptics may be required during particularly stressful of difficult behavior periods. However, these medications should only be used transiently due to their sedative effects and potential side-effects.

Down Syndrome: Causes and Risk Factors

Down syndrome is a genetic disorder caused by the presence of extra genetic material from chromosome 21. There are three different types of Down syndrome, each with its own cause and inheritance pattern. The most common form, full trisomy 21, is not inherited and accounts for 95% of cases. It occurs when there is a failure of chromosome 21 to separate properly during cell division, resulting in an extra copy of the chromosome. This can happen randomly, with the extra chromosome coming from the mother 88% of the time and from the father 12% of the time.

The second type, translocation Down syndrome, is inherited and accounts for 2-3% of cases. It occurs when a piece of chromosome 21 breaks off and attaches to another chromosome, resulting in extra genetic material. This type of Down syndrome is caused by a balanced translocation, which means that the parent carrying the translocation has no signs of symptoms of the disorder.

The third type, mosaic Down syndrome, is not inherited and also accounts for 2-3% of cases. It occurs as a random event during cell division early in fetal development, resulting in some cells having an extra copy of chromosome 21 while others do not.

The risk of having a child with Down syndrome increases as a mother gets older. At age 35, the risk is 1 in 385; at age 40, the risk is 1 in 106; and at age 45, the risk is 1 in 30. It is important for women to be aware of these risk factors and to discuss them with their healthcare provider if they are planning to have a child.

Kohlberg’s Six Stages of Moral Development

Kohlberg’s theory of moral development consists of six stages that can be categorized into three levels. The first level is the preconventional stage, which is characterized by obedience and punishment orientation, where the focus is on the direct consequences of actions and unquestioning deference to power. The second stage is the self-interest orientation, where right behavior is defined purely by what is in the individual’s own interest.

The second level is the conventional stage, which is characterized by interpersonal accord and conformity, where the focus is on how the individual will appear to others. The behavior should accord with a consensus view on what is good. The second stage is the authority and social order obedience driven, where what is lawful is judged to be morally right. Right behavior is dictated by societal rules, and there is a greater respect for social order and the need for laws.

The third level is the postconventional stage, which is characterized by the social contract orientation, where individual rights determine behavior. The individual views laws and rules as flexible tools for improving human purposes. The fourth stage is the universal ethical principles orientation, where the right action is the one that is consistent with abstract reasoning using universal ethical principles.

It is important to note that the age ranges for Kohlberg’s developmental stages are rough guides, and sources vary widely. Kohlberg developed his stage theory following an experiment he conducted on 72 boys aged 10-16. However, the theory is criticized as sexist as it only included boys.

Piaget’s Stages of Development and Key Concepts

Piaget developed four stages of development that describe how children think and acquire knowledge. The first stage is the Sensorimotor stage, which occurs from birth to 18-24 months. In this stage, infants learn through sensory observation and gain control of their motor functions through activity, exploration, and manipulation of the environment.

The second stage is the Preoperational stage, which occurs from 2 to 7 years. During this stage, children use symbols and language more extensively, but they are unable to think logically of deductively. They also use a type of magical thinking and animistic thinking.

The third stage is the Concrete Operational stage, which occurs from 7 to 11 years. In this stage, egocentric thought is replaced by operational thought, which involves dealing with a wide array of information outside the child. Children in this stage begin to use limited logical thought and can serialise, order, and group things into classes on the basis of common characteristics.

The fourth and final stage is the Formal Operations stage, which occurs from 11 through the end of adolescence. This stage is characterized by the ability to think abstractly, to reason deductively, to define concepts, and also by the emergence of skills for dealing with permutations and combinations.

Piaget also developed key concepts, including schema, assimilation, and accommodation. A schema is a category of knowledge and the process of obtaining that knowledge. Assimilation is the process of taking new information into an existing schema, while accommodation involves altering a schema in view of additional information.

Overall, Piaget’s stages of development and key concepts provide a framework for understanding how children learn and acquire knowledge.

Mahler’s Separation-Individuation theory of child development proposes that personality development occurs in distinct stages. The first stage, the Autistic phase, occurs during the first few weeks of life, where the child is mostly sleeping and cut off from the world. The second stage, the Symbiotic phase, lasts until around six months of age, where the child sees themselves and their mother as a single unit. The third stage, Separation-Individuation, has four subphases. The first subphase, Differentiation, occurs between six to ten months, where the child begins to see themselves as an individual and experiences separation anxiety. The second subphase, Practicing, occurs between ten to sixteen months, where the child explores connections with the external world and people other than the mother. The third subphase, Rapprochement, occurs between sixteen to twenty-four months, where the child struggles to balance their desire for independence and proximity to the mother, often resulting in tantrums and the use of transitional objects. The fourth subphase, Object constancy, occurs between twenty-four to thirty-six months, where the child accepts the idea of object constancy and is more comfortable with the mother being separate for periods of time.

Erik Erikson and Daniel Levinson expanded the understanding of adult development. Erikson proposed a life-span model of human development consisting of eight successive psychosocial stages, each associated with an inherent conflict of crisis that the individual must encounter and successfully resolve to proceed with development. Levinson proposed a developmental theory consisting of universal stages of phases that extend from the infancy state to the elderly state, based on biographical interviews of 40 men in America. Both theorists maintained that personality develops in a predetermined order and builds upon each previous stage, and that failure to successfully negotiate a stage can result in a reduced ability to complete further stages and therefore a more unhealthy personality and sense of self. However, Levinson’s theory is age-based rather than event-based, and his model proposed a ‘life sequence’ consisting of a series of alternating stable (structure-building) periods and cross-era transitional (structure-changing) periods, with transitional periods typically lasting 5 years.

Psychosexual Development

The psychosexual theory of development, developed by Freud, outlines a number of stages that individuals go through in their development. These stages are quite complex, but tend to come up in exams. The stages include the oral stage, which occurs from birth to 18 months, where pleasure and needs are explored through sucking, swallowing, and biting. The anal stage occurs from 18 to 36 months, where pleasure and needs are explored through bowel and bladder elimination and retention. The phallic stage occurs from 3 to 5 years, where boys pass through the Oedipal complex and girls the Electra complex. Girls are also said to develop penis envy in this stage. The latency stage occurs from 5 to puberty, where the sexual drive remains latent. Finally, the genital stage occurs from puberty to adulthood, where a person achieves independence from their parents and forms intimate relationships with others.

Attachment Theory and Harlow’s Monkeys

Attachment theory, developed by John Bowlby, suggests that children have an innate tendency to form relationships with people around them to increase their chance of survival. This attachment is different from bonding, which concerns the mother’s feelings for her infant. Children typically single out a primary caregiver, referred to as the principle attachment figure, from about 1-3 months. The quality of a person’s early attachments is associated with their adult behavior, with poor attachments leading to withdrawn individuals who struggle to form relationships and good attachments leading to socially competent adults who can form healthy relationships.

Bowlby’s attachment model has four stages: preattachment, attachment in the making, clear-cut attachment, and formation of reciprocal attachment. The time from 6 months to 36 months is known as the critical period, during which a child is most vulnerable to interruptions in its attachment. Attachments are divided into secure and insecure types, with insecure types further divided into avoidant and ambivalent types.

Harlow’s experiment with young rhesus monkeys demonstrated the importance of the need for closeness over food. The experiment involved giving the monkeys a choice between two different mothers, one made of soft terry cloth but provided no food and the other made of wire but provided food from an attached baby bottle. The baby monkeys spent significantly more time with their cloth mother than with their wire mother, showing the importance of attachment and closeness in early development.