23rd November 2023

Conceptualising Development

Nature and Nurture

‘Give me a dozen healthy infants … and I’ll guarantee to take anyone at random and train him to become any type of specialist I might select – doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocation, and race of his ancestors.’ – John Watson

Temperament

Academic psychologists have come a long way from the radically behaviouristic and naively pragmatic era in which John Watson could boast those words above. A generation of developmental scholarship has demonstrated to us that human beings are anything but blank slates at birth. From shyness to stimulation seeking, we know that people’s attributes are genetically influenced and cannot be seen as merely the result of their upbringing. But how does one affect the other?

The nature of a person is their temperament and other fixed attributes. As articulated by Arnold Buss and Robert Plomin (1987), temperament refers to ‘traits observable by 2 years of age that are genetic in origin’. The three core dimensions of temperament include emotionality, activity, and sociability, which are believed to be precursors for adult personality.

Alexander Thomas and Stella Chess (1968) employed factor analysis in their New York longitudinal study, a 30-year longitudinal study (initially 6 years) of 138 children, observing childhood temperaments during their infancy and followed up at 5, 18, and 22 years. The study identified nine temperamental features, including activity level, biological rhythms, sensitivity, intensity of reaction, adaptability, approach/withdrawal, persistence, distractibility, and mood, which they subsequently grouped into four distinct clusters.

• ‘Easy child’ – 40%
• ‘Difficult child’ – 10%
• ‘Slow to warm up a child’ – 15% 
• Does not fall into a category – 35%

Children’s temperament is only one example of the unchangeable aspects of people’s individual psychologies. But what about the things that can be changed – their nurture? 

Examination of gene-environment interactions 

In the RCPsych syllabus, the gene-environment debate is focused on intelligence.

We must approach the concept of human intelligence with a nuanced understanding of its complex nature. While studies below estimate a heritability of 40-50% for IQ, the relationship between genes and IQ can vary depending on the environmental context.

For example, the impact of genetic factors on IQ is more pronounced in individuals from high socioeconomic status (SES) families than in individuals from low SES families. According to Turkheimer et al.’s (2003) meta-analysis, in low SES families, environmental factors such as poor nutrition, lack of access to education, and exposure to environmental toxins may hinder the expression of genetic potential for intelligence.

Tucker-Drob et al. (2013) examined the relationship between family SES and the heritability of IQ in a sample of over 10,000 twins and also found that the heritability of IQ was higher in high-SES families compared to low-SES families and that the environmental context accounted for a significant portion of the variation in the heritability estimates.

The Minnesota transracial adoption study (MTAS) (Scarr & Weinberg, 1977; Weinberg, Scarr, & Waldman, 1992) also provides evidence for gene-environment interaction in the development of IQ. This study found that Black and interracial children whom White families adopted had higher IQ scores than those who remained in foster care or were adopted by non-White families. The study also found that the IQ scores of the adopted children were more strongly correlated with the IQ scores of their adoptive parents than their biological parents, suggesting that the environmental context had a greater impact on their IQ than their genetic background.

Plomin and Deary (2015) argue that intelligence is a highly polygenic trait, with many genes involved in its development, each contributing only a small amount to the variation in IQ scores. They suggest that genetic influences on intelligence are likely to be highly complex and interactive, with multiple genetic variants working together in different ways at different stages of development.

Savage, Jansen and Stringer et al. (2018) conducted a genome-wide association study (GWAS) to identify genetic variants associated with IQ and found that the effects of individual genetic variants on IQ were small and highly variable, with no single variant accounting for more than a small fraction of the variation in IQ scores. While genetic influences on intelligence are highly polygenic and complex, there is evidence for some genetic overlap between different cognitive abilities.

These studies suggest that the development of IQ is influenced by a complex interplay between genetic and environmental factors, with the impact of genetic factors on IQ being modulated by the environmental context in which the individual develops.

References 

• Goldsmith, H. Hill, et al. “Roundtable: What is temperament? Four approaches.” Child development (1987): 505-529.
• Thomas, A., Chess, S., & Birch, H. G. (1968). Temperament and behaviour disorders in children. New York: New York University Press
• Turkheimer, E; Haley, A; Waldron, M; D’Onofrio, B; Gottesman, II (November 2003). “Socioeconomic status modifies heritability of IQ in young children”. Psychological Science. 14 (6): 623–8. doi:10.1046/j.0956-7976.2003.psci_1475.x. PMID 14629696.
• Briley, Daniel A. and Elliot M. Tucker-Drob. “Explaining the Increasing Heritability of Cognitive Ability Across Development.” Psychological Science 24 (2013): 1704 – 1713.Weinberg, Richard A., Sandra Scarr, and Irwin D. Waldman. “The Minnesota Transracial Adoption Study: A follow-up of IQ test performance at adolescence.” Intelligence 16.1 (1992): 117-135.
• Plomin, Robert, and Ian J. Deary. “Genetics and intelligence differences: five special findings.” Molecular Psychiatry 20.1 (2015): 98-108.
• Savage, J.E., Jansen, P.R., Stringer, S. et al. Genome-wide association meta-analysis in 269,867 individuals identifies new genetic and functional links to intelligence. Nat Genet 50, 912–919 (2018)

Historical Models of Development, Maturational Tasks and Stage Theories

Why bother learning these psychodynamic models of development, you may ask? 

Well, a central diagnostic task of a clinical interview is assessing what developmental level a person is characterologically organised. Are the main issues with which the person repeatedly struggles those of the earliest phase of life, the one Freud called oral, and Mahler called symbiotic? If so, the interviewer will hear themes such as the Eriksonian conflict between basic trust and mistrust, the Sullivanian confusion of ‘me versus not me’, and other derivatives of the infant’s struggle to define a sense of existence and personhood.

Or is the person preoccupied with the themes and conflicts of the phase Freud called anal and Mahler called separation–individuation? If so, the clinician will feel a sense of dyadic struggle, of Erikson’s (1950) ‘autonomy versus shame and doubt’ and of Sullivan’s (1947) ‘good me versus bad me’, see how these theories come together. Maturational challenges will categorise the former patient as neurotic and the latter patient as borderline and inform us of how their reality testing and affect regulation will be in each case. 

This chapter will just briefly overview these theoretical models in understanding development. I hope these theories indirectly influence a sensibility that informs your day-to-day interactions with your patients – not just for the RCPsych exams! By discussing their problems through a developmental lens, patients can learn to see themselves as grappling with maturational challenges rather than as stymied by unrelenting, static realities. 

According to Jean Piaget, development occurs in hierarchical stages; each stage is qualitatively different; and the stages consist of invariant functions, and all children undergo these sequentially. Let’s start from the very beginning with Freud.

Freudian stages of psychosexual development

In this section, I oversimplify Freudian theory for didactic purposes, omitting many interesting problems and complications in it. 

Sigmund Freud’s original development theory stressed three ‘infantile’ (i.e., preschool) stages, the oral, anal, and oedipal, each of which had predictable issues and conflicts, mastered differently depending on the child’s constitution and the caretakers’ interventions. These were typically resolved by about age 6 into the main outlines of someone’s permanent personality structure. (Freud also talked about minor transitional phases in the infantile era that applied differentially to the two sexes, including a urethral phase, a phallic phase, and a reverse or ‘negative’ oedipal phase, but these have been less emphasised in the literature and include too many idiosyncratic issues to go into here.)

Oral phase – 0-18 months

According to Freud, in the oral phase, the child’s sensory experience is organised around the mouth, the chief organ for expression, exploration, and enjoyment, and the means of connection with the nursing mother from whom the child is not yet psychologically differentiated. 

Anal phase – 18-36 months

From about eighteen months to three years, the child’s preoccupation shifts to anal concerns, partly because of the maturation of the anal sphincter muscle and partly because the toilet training scenario typically represents the first conflict between the child’s natural proclivities and the demands of civilisation, represented by the child’s caretakers. Associated infantile concerns involve struggles between compliance and rebellion, cleanliness and mess, giving and withholding, promptness and lateness, autonomy and shame, sadism and masochism – all very dyadic issues. The dramas of this phase all seem to involve the question of agency. Colloquially, the Freudian ‘anal’ phase has been nicknamed the ‘terrible twos’ because of the intense pitting of the toddler’s will against that of the parents at this time. 

Oedipal phase – 3-6 years 

With the inception of the oedipal phase at about age three, the child has become cognitively capable of understanding that two other people can have a relationship in which he or she is not a player. The child’s preoccupations shift to a fascination with issues about power, relationships, and identity. He or she gets very interested in sex differences, generating imagery about castration, mutilation, and other infantile theories about the distinctions between males and females. Children this age are raptly curious about the origins of babies, and they construct elaborate fantasies and experience associated jealousies about their parents’ sexual lives. By somewhere around age three or four, normally developing children also have an awareness of personal agency that is not defined by dyadic power struggles as in the previous phase. 

They also come to an awareness of the reality of death, which, because of their unfinished sense of the independence of idea from action, makes them frightened by their natural wishes to get one parent out of the way and possess the other. Guilt and projected guilt, as in bedtime anxieties about hidden attackers, are typical. Fears of retribution for hostile wishes are eventually resolved by identification with primary caregivers, especially the parent with whom the child feels most competitive (‘I can be like daddy and have someone like mommy when I grow up’). Children at this age need to idealise their caregivers, who, as self-psychologists have noted (e.g., Kohut, 1977), must be attuned enough to be idealised in the first place and non-defensive enough to tolerate the child’s de-idealisation. This normal, expectable dethroning of the parents starts around the end of the oedipal phase (when the kindergarten teacher starts knowing more than mommy). A cardinal achievement of this developmental era is attaining a complex and well-internalised sense of conscience that is the natural consequence of complex identifications with childhood authorities. In analytic lingo, a mature superego replaces the primitive all-good and all-bad images of the previous stage. 

Latency phase – 6 years to puberty

Freud postulated a latency phase after age 6 or so, in which the child, having developed mature defences, notably repression, that keeps disturbing ideas out of consciousness, is temporarily relieved of the intensity of coping with powerful primal urges and can concentrate on learning and socialisation. 

Genital phase – Puberty

The hormonal assault of puberty ushers in adolescence and the final and sometimes stormy consolidation of all the early challenges and resolutions. With sexual maturity, it becomes possible for people to compress all their oral, anal, and oedipal issues into a pleasurable experience of adult genitality, an ideal condition characterised by a person’s capacity to integrate love, aggression, dependency, and sexuality into a relationship with another person. As I have in this account, most of Freud’s clinical writing emphasised the first three phases, as he believed that neurotic problems in adulthood derive from universal ‘childhood neuroses.’

Eriksonian stages of psychosocial development 

Erik Erikson regarded his contribution as an elaboration of Freudian theory rather than replacing it. Each section of the Eriksonian wheel below describes a maturational task, which refers to the psychological challenges that individuals must overcome at different stages of development to achieve psychological maturity. These tasks are thought to be innate, biologically determined, and universal, and are believed to follow a fixed sequence of development that is independent of environmental factors.

Maturity could be defined as a multi-dimensional concept that involves the development of cognitive, emotional, and social skills necessary for functioning effectively and adapting to the demands of life.

Most interesting is that Erikson frequently commented in his last decade (1997) that if he were writing his lifespan theory again, he would not have lumped everything from the sixties into one category. Only by reaching old age himself did he emotionally appreciate the profound difference between the psychology of someone 65 and that of someone 85. Psychoanalytic knowledge of the geriatric stages of life is not well developed.

Klein’s theory of psychological development

Melanie Klein’s influential theory of psychological development posits that infants progress through two major positions in their early development: the paranoid-schizoid position and the depressive position. These positions represent fundamental modes of relating to the world and reflect the infant’s emerging capacity to process their experiences.

Paranoid-schizoid position – Birth to 4-6 months

The infant tends to split their experiences into good and bad, projecting negative feelings onto external objects. This position is marked by primitive anxieties, such as the fear of annihilation and the infant’s need for protection from internal and external dangers.

Depressive position – 6 months onwards

This is the infant’s ability to integrate good and bad experiences and form more complex and realistic views of themselves and the world around them. The infant begins to recognise that the external object has both positive and negative qualities and develops a more nuanced understanding of their relationships with others.

Klein believed that the successful resolution of these positions was crucial for the development of a healthy sense of self and the ability to form satisfying relationships with others. Furthermore, Klein emphasised the role of the mother or primary caregiver in facilitating this development, by providing a secure and supportive environment for the infant’s exploration and growth. Klein’s theory has been influential in shaping contemporary psychoanalytic thinking, particularly in the area of object relations theory, which emphasises the importance of interpersonal relationships in shaping the developing self. The theory also highlights the significance of early experiences in shaping individuals’ psychological development, underscoring the importance of early intervention and prevention efforts in addressing the impact of adverse childhood experiences.

Marcia’s development of adolescent identity 

James Marcia elaborates on Erikson’s proposal of the fifth stage of psychosocial development, by using the identity status interview, a semi-structured interview. You may recall that Erikson had suggested that the normative conflict occurring in adolescence is the opposition between identity achievement and role confusion. 

Marcia suggests that this stage consists neither of identity resolution nor identity confusion, as Erikson claimed, but is better understood as the extent to which one has both explored and committed to an identity in a variety of life domains, including politics, occupation, religion, intimate relationships, friendships, and gender roles.

Identity diffusion

At one end of the spectrum is identity diffusion, where the teenager makes no firm commitments for the future, with no identity issues considered with no goals whatsoever. They remain in an amorphous state of identity, with some reporting having little interest in identity crisis or reporting repeated indecision.

Identity achievement

The goal is to ultimately get to the other end of the spectrum called identity achievement. This is where the teen has carefully considered various alternatives and made firm future commitments after experiencing a crisis and working it through.

Identity moratorium

The process to achieve is identity moratorium, where the teen goes through intense exploration in the midst of a crisis, whose commitments are either absent or are only vaguely defined, but who are actively exploring alternatives. 

Identity foreclosure

Identity foreclosure is where the teen adopts the traditional and cultural norms of their parents or surrounding culture rather than exploring or forming their own unique path. They may foreclose on the handed-down identity willingly or under coercion and pressure. As Marcia himself put it, ‘The individual about to become a Methodist, Republican farmer like his Methodist, Republican farmer father, with little or no thought in the matter, certainly cannot be said to have ‘achieved’ an identity, despite his commitment.’\

Sullivan’s model of development 

Harry Stack Sullivan’s model of development posits that human beings are fundamentally social creatures, and that personality development is shaped by interpersonal experiences and relationships. Sullivan emphasised the importance of the individual’s interactions with others, particularly during childhood and adolescence, in shaping their sense of self and their capacity for healthy relationships. Sullivan proposed that individuals progress through several developmental stages: 

Infancy

Beginning with the infancy stage, the infant experiences their caregiver as part of themselves. 

Good me vs bad me – 5-10 years

In the ‘good me vs bad me’ stage, which typically occurs around age 5 or 6, the child develops an internalised sense of self and begins to differentiate between positive and negative aspects of themselves. This stage is marked by the child’s efforts to incorporate positive aspects of themselves into their self-concept and to disown negative aspects of themselves.

Me vs not me – 10-13 years

In the Juvenile stage, which typically occurs around age 9 or 10, the child begins to develop a sense of ‘me vs not me’ as they increasingly differentiate themselves from others. During this stage, the child’s sense of self is influenced by their interactions with peers and authority figures, and they begin to form more complex relationships with others.

Preadolescence – 13-15 years 

In the preadolescence stage, which typically occurs around age 12 or 13, the individual experiences significant changes in their self-concept and their relationships. Sullivan suggested that this stage is marked by significant interpersonal tension, as individuals struggle to balance their desire for intimacy with their fear of rejection and abandonment.

Adolescence – 15 years onwards

Finally, in the adolescence stage, which typically occurs around age 14 or 15, the individual experiences significant changes in their self-concept and their capacity for relationships. During this stage, the individual faces the challenge of separating from their parents and establishing their own identity. Sullivan believed that the successful resolution of this task is necessary for forming a healthy sense of self and forming mature relationships with others.

Mahler’s separation-individuation stages of child development

Margaret Mahler is a neo-Freudian who dissects Freud’s pre-oedipal stages. The separation-individuation theory is a psychodynamic, developmental theory that outlines the stages of psychological growth that an infant goes through as they move towards separation from their primary caregiver and establish their own independent identity.

Autistic – 0-2 months

A child spends most time in sleep as if the intrauterine aloofness continues. 

Symbiotic – 2-5 months

The inner and outer world is studied via senses but perceives mother and self as one unit.

Separation-individuation

Differentiation – 5-10 months

During this stage, the infant develops a sense of self and starts to differentiate themselves from their primary caregiver. This is a critical stage of development, as it is during this time that the infant learns to tolerate being away from their caregiver and to explore the world around them.

Practising – 10-18 months

During this stage, the infant starts to move around and explore their environment more actively but still relies heavily on their primary caregiver for support and comfort.

Rapprochement – 18-24 months 

Alternating drives to be autonomous and dependent; Able to explore alone but requires comfort and reassurance on return.

Object constancy – 2-5 years

Understand that the mother will not be lost if temporarily away; hence, she can function independently.

Piaget’s theory of cognitive development 

Piaget’s theory is a developmental theory that focuses on how children learn and develop their thinking abilities. Piaget identified four stages of cognitive development that occur in a fixed sequence from birth through adolescence. I won’t go through them here as this will be covered in greater detail in other chapters.

References

• Freud, S. (1923). The ego and the id. Standard Edition, 19, 13–59.
• Erikson, E. H. (1950). Childhood and society. New York: Norton. Erikson, E. H. (1968). Identity: Youth and crisis. New York: Norton. Erikson, E. H. (1997). The life cycle is completed. New York: Norton.
• Klein, M. (1946). Notes on some schizoid mechanisms. International Journal of Psycho-Analysis, 27, 99–110.
• Marcia, J. E., (1966), Development and validation of ego identity status, Journal of Personality and Social Psychology 3, pp. 551-558
• Sullivan, H. S. (1947). Conceptions of modern psychiatry. New York: Norton. 
• Sullivan, H. S. (1953). Interpersonal theory of psychiatry. New York: Norton. 
• Sullivan, H. S. (1954). The psychiatric interview. New York: Norton.
• Mahler, M. S. (1968). On human symbiosis and the vicissitudes of individuation. New York: International Universities Press. 
• Mahler, M. S. (1971). A study of the separation–individuation process and its possible application to borderline phenomena in the psychoanalytic situation. In The selected papers of Margaret S. Mahler (Vol. 2, pp. 169–187). New York: Aronson, 1979. 
• Mahler, M. S., Pine, F., & Bergman, A. (1975). The psychological birth of the human infant. New York: Basic Books.

Developmental Milestones in Children

Developmental milestones are not set in stone and can vary from child to child. While there is a general timeline for when children typically reach these milestones, there is a wide range of what is considered normal development. Some children may achieve certain milestones earlier or later than others, and that is typically considered within the range of typical development.

These milestones have been developed through research studies and observations of large populations of children. The specific criteria and timeline for each milestone have been established by a range of organisations, including the American Speech-Language-Hearing Association (ASHA), the Centers for Disease Control and Prevention (CDC), and the World Health Organization (WHO). These milestones are used as guidelines to help identify children who may be experiencing delays in their development and may require further evaluation or intervention. It is important to remember that every child is unique and will develop at their own pace, so it is important to consider the whole child when evaluating their development.

Speech and language milestones

• 6 weeks – 2 months – First social smile and cooing.
• 3 months – Differentiate familiar and unfamiliar faces and localise sound sources.
• 6 months – Babbles (gaga, dada).
• 9-10 months – Babbles tunefully.
• 1 year – One-word stage (mamma, doggie).
• 16-18 months – 18-40 words.
• 2 years – Two-word stages with no propositions (mummy go, daddy go), 80-100 words.
• 3 years – Basic adult grammatical sentence.
• 5 years – Adult speech.
• Language is slower to develop in boys, in twins, in larger families, in those from social classes 4 and 5, and in children with a lack of stimulation, e.g. deaf and neglected children.

Visual milestones

• 20-week foetus – Responds to bright light flashed on the abdominal wall.
• Birth – Vision is the least developed sense with acuity at 20/300, but can still track and scan objects, discriminate brightness levels, fixed focus at 20 cm, can see around 8-10 inches and have pupillary reflexes.
• 1 month – Differentiates faces from other stimuli, with a preference for face-like complex stimuli.
• 2 months – Depth perception, prefers 3D rather than 2D representations of faces.
• 4 months – Colour vision and accommodation reflex develop.
• 6 months – Accurate acuity (6/6) is achieved in most infants.

Reading an analogue clock

• Reception (ages 4-5) – Read the time to the hour.
• Year 1 (ages 5-6) – Read the time to the hour or half hour.
• Year 2 (ages 6-7) – Read the time to the hour, half hour, or quarter hour.

Motor milestones

Gross motor

• 3 months – Holds head up unaided.
• 6 months – Sits unaided, rolls from front to back.
• 12 months – Cruises by holding furniture.
• 18 months – Walks independently.
• 24-30 months – Runs and climbs stairs unaided with rails.
• 3 years – Feeds and simply dresses oneself.
• 4 years – Hops on one leg.
• 5 years – Climbs stairs one foot at a time.

Fine motor

• 3 years – Draws a circle.
• 4 years – Draws a cross.
• 4.5 years – Draws a square.
• 5 years – Draws a triangle.
• 7 years – Draws a diamond.

Play milestones

Children’s play activities are categorised according to the quality of interactions among each other.

• <2 years – Solitary play – The child plays on its own.
• 2 years – Parallel play – The child plays along with other children.
• 3 years – Co-operative play – The child interacts with other children in complementary ways, like sharing turn-taking.
• 5 years – Rule-governed play – The child understands the rules of games.

Development of the theory of mind 

Theory of mind refers to people’s intuitive understanding of their own and other people’s minds or mental states, including beliefs and thoughts. To use psychodynamic lingo, the theory of mind uses projection to form the basis of empathy through the projection of personal experiences to understand someone else’s subjective world. It develops by degrees from a very early age in humans:

• 3 years – Children normally have a well-developed theory of mind but cannot yet understand that people’s beliefs can be false. 
• 4 years – Children understand that people’s beliefs can be false too.

Development of gender 

Kohlberg’s (1966) classic stage theory of gender development (not his moral development) proposed that children can correctly identify their gender by 2 years of age, understand that their gender remains stable across time by 4 years of age, and understand their gender to be constant and independent of external features by 7 years of age.

However, it is now recognised that gender identity is a multidimensional construct that includes an individual’s knowledge of an attitude towards gender groups. The development of a transgender or gender-nonconforming identity involves a complex interplay of phenomena over time. Fluidity in gender identity is being increasingly recognised.

Developmental fears and anxiety

An appreciation of different maturational aspects of personality structure is enormously helpful in evaluating the nature of a person’s experience of anxiety or depression. When we listen to an anxious patient, we all tend to project into our understanding of that anxiety the kinds of issues that define our own anxious proclivities. But anxieties differ markedly, depending on whether their origin is in the symbiotic phase, the separation–individuation phase, or the oedipal phase. 

The first kind, generally referred to as annihilation anxiety, is the terror that the self will be overwhelmed, will be engulfed by another, and will cease to exist. It is the kind of anxiety that an unmedicated person in an acute schizophrenic state emanates. Annihilation anxiety survives in the psychology of most adults in residual fears of intimacy. One can easily find evidence of people’s anxiety that closeness with another person will threaten their independent existence.

The second kind, separation anxiety, affects all of us to some degree, as separations inevitably stimulate unconscious memory traces of frightening infantile disconnections, but it is an especially intense and central part of the experience of people organised at a borderline level of development. It is normally seen in infants at about 8 months (called stranger anxiety), which appears as an anxiety response to someone other than the caregiver. At the approach of a stranger, infants cry and cling to their mothers. Separation anxiety is most common at ages 10-18 months and generally disappears by the end of the third year. In the absence of the person to whom one is attached, one feels empty or insubstantial. It can be strong enough to keep a person in life-threatening situations, as when a battered spouse can deal more easily with the pain of physical abuse than the terror of loneliness. It can impel astonishing regressions and seemingly inexplicable explosions of hostility.

The third kind of anxiety, oedipal or superego anxiety, involves fears of punishment for unacceptable sexual, aggressive, or dependent strivings. There is no threat to the perception of reality and identity of the self, but one’s feeling of personal good-enoughness may be seriously compromised. Despite the fact that it originates after the child has consolidated a sense of self and reality, oedipal-level anxiety can be quite intense, given that oedipal fantasies typically involve ideas of death and retribution. The experience of personal success is a common trigger for oedipal anxiety: If an achievement has for someone the emotional significance of victory over a parent, he or she may become very anxious or symptomatic in the unconscious expectation of punishment for that crime.

Developmental trend of fears

• Infancy – Fear of loud noises, falling, strange objects and strange people. 
• 3 years – Fear of animals.
• 4-5 years – Fear of the dark. 
• >5 – Fear of imaginary creatures. 
• Late childhood – Fear of open spaces and sex.
• Teenage onwards – Fears of failure, illness and death.
• Fears that show no particular age trend – Fear of snakes and natural events like storms. 

References

• Hurvich, M. S. (1989). Traumatic moments, basic dangers and annihilation anxiety. Psychoanalytic Psychology, 6, 309–323.

Adversities and Development 

Stress vulnerability model

The stress vulnerability model proposes that individuals with certain genetic or biological vulnerabilities may be more susceptible to the negative effects of stressors, leading to the development of psychiatric disorders. 

• Caspi et al. (2003) conducted a longitudinal study of over 1,000 New Zealanders and found that individuals with a genetic polymorphism that reduces the expression of the enzyme monoamine oxidase A (MAOA), which is involved in the regulation of neurotransmitters such as serotonin and dopamine, were more likely to develop depression and antisocial behaviour in response to childhood maltreatment. This study suggests that the interaction between genetic vulnerability and environmental stressors can lead to the development of psychiatric disorders.
• Kendler et al. (1999) conducted a twin study of over 4,000 individuals and found that genetic factors accounted for approximately 50% of the variance in vulnerability to major depression, while environmental factors such as life events accounted for the remaining variance. This study suggests that both genetic and environmental factors contribute to vulnerability to depression.
• Monroe and Simons (1991) conducted a study of individuals with a history of depression and found that those who experienced greater life stressors in the six months prior to a depressive episode had a higher likelihood of relapse than those who experienced fewer stressors. This study suggests that the impact of stressors on depression risk may be particularly strong in individuals with a history of the disorder.

These studies suggest that the stress vulnerability model provides a useful framework for understanding the development of psychiatric disorders and that both genetic and environmental factors contribute to vulnerability to these disorders.

Adverse Childhood Experiences (ACE)

The concept of adverse childhood experiences (ACEs) was developed by Dr. Vincent Felitti and Dr. Robert Anda (1998). They conducted a ground-breaking study that surveyed over 17,000 individuals about their experiences of abuse, neglect, and household dysfunction during childhood, and then correlated those experiences with a range of health outcomes later in life.

ACEs comprise a diverse array of traumatic experiences, including abuse, neglect, household dysfunction, and exposure to community violence. Recent studies have demonstrated that ACEs are alarmingly prevalent, with a staggering two-thirds of participants reporting at least one ACE, and that these experiences exert a profound and long-lasting impact on one’s health and well-being. ACEs have the potential to derail normal developmental processes in childhood, culminating in a host of adverse health outcomes in adulthood, such as chronic physical illnesses, mental health disorders, and addiction.

For example, family instability can affect children to various extents depending on sex (boys affected > girls), age (younger > older) and temperament (hyperactive > placid). This has a demonstrable effect on a child’s cognitive achievements; the most common psychopathology noted is behavioural difficulty. A child who experiences abuse during the sensitive period for attachment (around 6-18 months of age) may struggle to form secure attachments with caregivers, leading to difficulties with emotional regulation and social relationships later in life.

References

• Caspi, A., Sugden, K., Moffitt, T. E., Taylor, A., Craig, I. W., Harrington, H., McClay, J., Mill, J., Martin, J., Braithwaite, A., & Poulton, R. (2003). Influence of life stress on depression: moderation by a polymorphism in the 5-HTT gene. Science (New York, N.Y.), 301(5631), 386–389. https://doi.org/10.1126/science.1083968
• Kendler, K. S., & Baker, J. H. (2007). Genetic influences on measures of the environment: a systematic review. Psychological medicine, 37(5), 615-626.
• Monroe, S. M., & Simons, A. D. (1991). Diathesis-stress theories in the context of life stress research: implications for the depressive disorders. Psychological bulletin, 110(3), 406.
• Felitti, V. J., Anda, R. F., Nordenberg, D., Williamson, D. F., Spitz, A. M., Edwards, V., Koss, M. P., & Marks, J. S. (1998). Relationship of childhood abuse and household dysfunction to many of the leading causes of death in adults. The Adverse Childhood Experiences (ACE) Study. American journal of preventive medicine, 14(4), 245–258. https://doi.org/10.1016/s0749-3797(98)00017-8

Methodology for Studying Development

In developmental psychology, researchers often use cross-sectional studies to compare children of different ages on a particular behaviour or developmental feature. However, inter-individual variations can distort the true picture of development. 

To obtain more reliable estimates, longitudinal studies are often employed where the same children are studied repeatedly over a prolonged period of time with respect to a developmental feature. Though time-consuming, this approach provides more accurate and precise information on developmental changes.

It is important to note that in developmental psychology, the identification of a risk factor does not necessarily imply causation, as the relationship could be mediated by a third variable (mediator). For example, a putative risk factor may be the outcome of the disorder rather than the cause (reverse causality), or there may be multivariate relationships that partially account for the relationship between a risk factor and a disorder. In such cases, the mediator could be a protective factor or a buffer that reduces the risk in an individual. It is important to consider such mediators in order to fully understand the complex relationships between risk factors and developmental outcomes.