[10.1] Physical Development from Conception through Infancy

Question 1

Developmental Psychology

Answer 1

• developmental psychology: the study of human physical, cognitive, social, and behavioural characteristics across the lifespan

Question 2

Methods for Measuring Developmental Trends

Answer 2

• cross-sectional design: used to measure and compare samples of people at different ages at a given point in time
  
  • e.g. to study cognition from infancy to adulthood, you could compare people of different age groups (e.g. groups of 1-, 5-, 10-, and 20-year-olds)
• longitudinal design: follows the development of the same set of individuals through time
  
  • select a sample of infants and measure their cognitive development periodically over the course of 20 years

Question 3

Strengths and Weaknesses of Developmental Trend Experiments

Answer 3

cross-sectional strengths and weaknesses:

• relatively cheap and easy to administer; allow a study to be done quickly
• cohort effects: differences between people that result from being born in different time periods
• do differences between the age groups reflect a normal developmental process or do they reflect more general differences between people born into these time periods?

longitudinal strengths and weaknesses:

• fix the problem of cross-sectional design
• following a single group of people for a long period of time can be very costly and time-consuming
• attrition: when participants drop out of a study for some reason, such as losing interest or moving away

Question 4

Patterns of Development: Stages and Continuity

Answer 4

• stages: development is seen as a progression of abrupt transitions in physical or mental skills, interspersed with slower, more gradual change
• transition from stage to stage involves rapid shifts in thinking and behaving, and fundamental shifts in the types of abilities a child can perform
• complex interactions between genetics and the envi- ronment are constantly shaping developmental processes

Question 5

The Importance of Sensitive Periods

Answer 5

• sensitive period: a window of time during which exposure to a specific type of environmental stimulation is needed for normal development of a specific ability
  
  • e.g. to become fluent in their native language, infants need to be exposed to speech during their first few years of life
• long-term deficits can emerge if the needed stimulation is missing during a sensitive period

Question 6

Zygotes to Infants: Fertilization and Gestation

Answer 6

• the fetus’s development is being shaped by both genetic and environmental factors
• zygote: the initial cell formed when the nuclei of egg and sperm fuse
• germinal stage: the first phase of prenatal development, which spans from conception to two weeks
• the ball of cells begins dividing, and travelling down to the uterus
• the blastocyst (ball of cells) splits into two groups; one becomes the fetus and the other the placenta
• embryonic stage: spans weeks two through eight, during which time the embryo begins developing major physical structures such as the heart and nervous system, as well as the beginnings of arms, legs, hands, and feet
• fetal stage: spans week eight through birth, during which time the skeletal, organ, and nervous systems become more developed and specialized

Question 7

Fetal Brain Development

Answer 7

• human brains develop most of their neural organization through interaction with the outside environment
• this makes us useless at birth, but highly adaptable
• the environment heavily structures us to be the way we are; we become the type of organism needed to live in the environment into which we’re born

Question 8

Nutrition, Teratogens, and Fetal Development

Answer 8

• mothers need about a 20% increase in energy intake during pregnancy, including protein and essential nutrients
• fetal malnutrition can have severe consequences, producing low-birth-weight babies who are more likely to suffer from a variety of diseases and illnesses, and are more likely to have cognitive deficits that can persist long after birth
• children malnourished in the womb are more likely to experience attention deficit disorders and difficulties controlling their emotions, due to underdeveloped prefrontal cortices and other brain areas involved in self-control
• teratogens: substances, such as drugs or environmental toxins, that impair the process of development
  
  • e.g. thalidomide: a sedative that was used to relieve pregnant women of morning sickness
  • caused miscarriages, blindness and deafness, and phocomelia (in which hands and feet, or both, functioned more like flippers than limbs)
  • fetal alcohol syndrome: abnormalities in mental functioning, growth, and facial development in the offspring of women who use alcohol during pregnancy.

Question 9

The Long-Term Effects of Premature Birth

Answer 9

• preterm infants: those born earlier than 36 weeks
  
  • typically have underdeveloped brains and lungs
• programs such as the Newborn Individualized Developmental Care and Assessment Program (NIDCAP) works to closely observe and given intensive care during early development of premature babies
• longitudinal studies have shown that children who get NIDCAP treatment function better than those who don’t
• however, the study only contained 22 participants and didn’t identify why or how NIDCAP works
• massasging preterm infants and encouraging kangaroo care also helps improve physical and psychological health

Question 10

Sensory and Motor Development in Infancy

Answer 10

• adults depend heavily on our top- down processes to help us label, categorize, perceive, and make sense of the world, but infants have developed very few top-down patterns when they are born

however, babies have started to make sense of their world even while in the womb

• during seven to eight months, babies are able to hear
• newborn babies show a preference for their mother’s voice over other women’s voices
• they also start to internalize the sounds of their own native tongue, even before they are born
• babies actually cry with an accent
• colour discrimination happens at about 2 months of age, depth perception at 4 months, and it takes a full 8 months before infants can perceive shapes and objects about as well as adults
• newborns prefer to look at stimuli that look like faces, compared to stimuli that have all the same features but are scrambled so that they don’t look like faces
• the visual system develops in response to the infant experiencing a world of diverse visual input
• the taste and olfactory systems are relatively well developed at birth

Question 11

Motor Development in the First Year

Answer 11

• reflexes: involuntary muscular reactions to specific types of stimulation
• the visual cliff: an experiment in which infants were unwilling to crawl over a piece of glass, seeming to understanding depth and danger right from birth; but researchers discovered that only babies who had some experience crawling showed fear of the deep end
• the development of motor skills seems to rely more on practice and deliberate effort, which in turn is related to environmental influences and cultural practices
• synaptogenesis: the forming of new synaptic connections
  
  • happening a lot through infancy and childhood, and continues throughout life
• synaptic pruning: the loss of weak nerve cell connections
  
  • accelerates during brain development through infancy and childhood, then tapers off until adolescence