developmental psychology ch3

Importance of prenatal development:

1. Fastest growth

2. Determined by biological factors, influenced by environmental factors

3. Basis for further development

What are the different phases of prenatal development?

1. Geminal phase (week 0-2)

2. Embryonic phase (week 3-8)

3. Fetal phase (week 9-38)

→ NOT the same as trimester (1st trimester covers all 3 phases)

Phase 1: Geminal phase (week 0-2)

• Primary objective: Development of zygote (cell created during fertilisation) into blastocysts (layered cell mass with a cavity)

• Nesting in uterine wall

• Vey sensitive phase: up to 50% are short lived here

• 250 cells

Phase 2: Embryonic phase (week 3-8)

Three principles of growth:

• Cephalocaudal principle

• Proximodistal principle

• Orthogenic principle

Cephalodaudal principle:

Development happens from top to bottom: head → bottom

Newborn head accounts for 25% of its’ total lengths and 13% of total body weight

vs

Adult head accounts for 2% of adult’s total weight and 12% total length

Proximodistal principle

Proximo = near, distal = far

🏠➡🌳

Meaning: Development happens from the center of the body outward.

• Control starts at the torso and moves out to the arms, then hands, then fingers.

• Example: Babies can first move their shoulders → then arms → then fingers.

Orthogenic principle:

Development proceeds from a general, undifferentiated state to a more specific, organised, and differentiated one.

• At first, abilities are broad and simple (e.g., general movements or emotions).

• Over time, these become more complex and specialised (e.g., coordinated hand movements or nuanced emotions).

• A single cell becomes billions of highly specialised cells.

• Ex. Organ sculpting - hands

What happens in week 3-4 of prenatal period?

The inside of the blastocyst develops into three layers:

• The endoderm - becomes the digestive and respiratory systens.

• The mesoderm - becomes the muscle, skeletal systems and learth/circulation.

• The ectoderm - becomes the skin and nervous system

Also neural tube: upper part becomes the brain and the lower part becomes the spinal cord

The endoderm:

Becomes the digestive and respiratory systems

The mesoderm:

Becomes the muscle, skeletal systems and learth/circulation

The ectoderm:

Becomes the skin and nervous system

Neural tube:

Basic nervous system

• Upper part: Becomes the brain

• Lower part: Becomes the spinal cord

What happens in week 5-8 of the prenatal period?

Formation of organs according to growth principles.

• Week 5 - arms develop, then palms of which fingers develop.

• By the end of week 8, most structures and organs are developed.

Phase 3: Fetal phase (week 9-38)

Primary objective: Growth of the embryo and refinement of structures

• Critical period for brain development

Brain development during fetal phase;

• Increase in size: Doubles in size from month 4 to 7

• From neural tube to 100 billion neurons

• Formation of brain folding like adult

What happens at 20 weeks in the prenatal phase?

• Fetal heartbeat

• Spine

• Brain (with cerebellum)

• Arms and hands

When can a baby survive?

• Age of viability now: 22 to 23 weeks

• 50/50 odds of survival by week 25

• Normal: 38 weeks

Central processes in prenatal brain development:

• Proliferation - rapid period of cell growth, originating from stem cells undergoing rapid cell division

• Migration - Cells move or travel to their intended location in the nervous system. Chemical signals may serve as a neural GPS, guiding cells to their destination.

• Differentiation - Cells change or transform into a particular type. At their destination, they set up camp and begin to communicate with surrounding neurons.

Environmental influences on prenatal development

Teratogens: harmful influences on unborn child

• Infectious diseases, medications, drugs, environmental toxins, nutritional deficiencies, maternal stress

• Most harmful during embryonic phase

• During 2/3nd trimester negative impact on brain development

• Dose dependent - 4 vs 1 cup of coffee

• Individual differences in effects (Maternal/fetal vulnerability unpredictable)

• Ex. Softenon to prevent nausea, turned out it makes kids have missing limbs

Smoking as a teratogen:

• Consequence during pregnancy: Nicotine constricts blood vessels > reduces blood flow, less nutrients and oxygen for the child, strongest effect in last trimester

• Possible birth consequences: Increased risk of miscarriage, born too early/too small

• Later potential consequences: Asthma, Cognitive problems, Behavioural regulation problems, ADHD, Antisocial behaviour

Hebb’s law

Neurons that fire together wire together → Repetition important for learning.

Neurons that are used repeatedly to perform a function become connected to facilitate function.

Use it or lose it: Synaptic pruning - old connections get deleted.

Synaptogenesis vs Synaptic pruning

Synaptogenesis: Synapse formation, one of the factors accounting for specialising our brains → Brain development is determined by biofactors, influenced by environment

Synaptic pruning: Synapse elimination

Myelination vs Apoptosis

Myelination: Insulation of neurons

Apoptosis: Programmed cell dealth

Brain lateralization:

Asymmetry and specialisation of functions of the two brain hemispheres.

Myelination;

= Lipid-rich (fatty) substance that speeds transmission.

Baby (until 1 year): Myelination of visual cortex → improvement of visual skills

Toddlers: Myelination of brain areas involved in language development → Vocabulary spurt

Adolescence: Myelination of prefrontal cortex → abstract thinking

Until adulthood: Continued myelination → better ability to integrate thoughts and emotions (compared to adolescents)

Brain development: Prefrontal cortex

Timing of synaptogensis and pruning varies across brain regions.

Prefrontal regions of the frontal lobe have the most prolonged development.

Around 1st year peak in synaptic density, around 15th year synaptic density at adult level, Myelination till adult

Gyrification (cortical folding):

Allows larger cortical surface area → greater cognitive functioning.

Brain development across the lifespan:

In childhood/adolescence: Brain maturation

In older age: Brain atrophy (shrinkage)

Coupe et al (2017): Comparison of brain volume trajectories

N = 2944 from 9 months to 9 years

Main findings:

• Grey matter: Mainly made of unmyelinated neurons and other cells → receives information and regulates outgoing information: Continuous lifelong decrease

• White matter: Mainly made out of myelinated neurons → transmits signals to other regions: Inverted u shape, maturation peak in middle life

Plasticity:

Processes that allow the organism to modify itself as response to the demands of the environment.

These processes could be due to:

• Development

• Learning and memory

• Cerebral changes (lesions, neurodegeneration, aging)

• Greatest during development.

Benefit: some brain areas can take over the function of other injured brain areas

But: Severe deprivation at very early age can have life-long consequences

Brain atrophy in elderly - details:

PFC and hippocampus shrink in older age → however, less atrophy in adults that were more fit.

More fit older adults have greater brain volumes than less fit counterparts.

Greater gray matter volume in PFC.

Greater hippocampal volume and benefit on memory levels.

Sensation vs Perception

Sensation: the product of the interaction between information and the sensory receptors - eyes, ears, tongue, nostrils, skin.

Perception: the interpretation of sensory information.

Sensory development in infants: Smell

Newborn prefer the smell of breast milk → soothing effect (ex. less crying when mom is there)

Newborn recognise the smell of their mom and her breast milk.

Sensory development in infants: Taste

Newborns prefer sweet taste and are sensitive to other basic tastes.

• For bitter, sour and salty: stop sucking and involve face.

• For sweet, suck more actively.

Sensory development in older adults: Smell

Decrease in smell, begins as early as adulthood - only for pleasant odors.

Sensory development in older adults: Taste

Decrease in sensitivity of taste - greater in men, but big differences between individuals.

Reason for decrease in taste: older adults produce less saliva → saliva transports chemical molecules.

Consequences for older adults - loss of taste and smell

Negative impact on quality of life and well-being → associated with higher mortality.

Less pleasure in eating food, but it’s also highly correlated to the environment.

Sensory development in infants: Touch

Skin to skin contact is important for bonding between baby and caregiver (increases chance of successful breastfeeding after birth).

Affects brain development (synaptogenesis, hormones) → Perhaps because babies become calmer and sleep better.

Sensory development in infants: Pain

Views on whether babies feel pain have changed a lot.

Late 19th and early 20th centuries: expressing pain is a reflex of babies’ underdeveloped brain.

1990: Research on hormonal and metabolic responses → Newborns and even fetuses can experience pain!

Sensory development in older adults: Touch

Reduced sensitivity in touch due to ex. reduced tactile receptors and altered timing in neural signalling due to demyelination.

Sensory development in older adults: Pain

Less sensitive to weaker levels of pain, but no difference from adults for higher levels of pain.

Consequences for older adults - loss of touch and pain

Importance of touch increases → pleasant touch becomes even nicer, perhaps because it becomes less frequent in older age.

More frequent chronic pain → adequate pain management improves functioning and well-being.

Sensory development in infants: Hearing

Hearing is important for social world and communication, more developed at birth than vision.

• Newborns (also during pregnancy): Recognise their mother’s voice and can distinguish it from foreign voices (but not their father’s voice) → greater exposure to mother’s voice.

• 1 month: Attention to speech directed to baby → begins learning.

• 7 months: No difference in response between native and other languages.

• 11-12 months: Greater response to native language, less sensitivity to sound contrasts that are unimportant in their native language.

Hearing - newborns:

Recognise their mother’s voice and can distinguish it from foreign voices (but not their father’s voice) → greater exposure to mother’s voice.

Hearing - 1 month

Attention to speech directed to baby → begins learning.

Hearing - 7 months

No difference in response between native and other languages.

Hearing - 11-12 months

Greater response to native language, less sensitivity to sound contrasts that are unimportant in their native language.

Development in older adults: Hearing

In general, deterioration in hearing.

Due to decrease of hair cells in the cochlea, hearing loss at high frequencies, typical of presbyacusis (age-related hearing loss).

Due to decrease in ganglion cells, higher threshold for pure tones.

1/3 of adults around 60 and 80% of 85+ adults have hearing loss (greater in men).

Reduced auditory threshold can lead to:

Disturbances understanding language/conversation - especially with background noise.

Tinnitus (ear ringing), hypersensitivity for noise.

No significant limitations in daily living

Limitations in leisure activities - ex. listening to radio, discussion with many people or with noise

Limitations in interpersonal activities and leisure activities can lead to higher depression.

Hearing in older age: Adaptation

Changing the environment: both social and spatial (rooms without noise, loud speaking)

Compensation tools: Hearing aids - consistent application, knowing how to use it, but often unrealistic expectations/advice in limitations

Sensory development in infants: Vision

Vision matures latest of baby’s sense, but already fetus respons to bright lights.

Vision - newborns

Sharp vision at about 30cm (distance from caregiver)

Prefers high contrast and patterns, cannot yet see sharply (low visual accomodation).

Vision - 3 months

Color vision (at birth the receptors aren’t mature yet)

Vision - 1 year

Same as adults

Form perception:

Recognition of patterns that from an object, based on motion information develops within 3 months, in months before focus on outer contours.

Face perception: Newborn can discriminate faces from non-faces

From 2/3 months: meaningful perception of a face

• 2 months: preference for speaking faces (move and make sounds)

• 8 months: fear bias = hypersensitivity to facial expressions of fear

• 9 months: less sensitive to facial differences in other ethnic groups

Why faces?

Innate preference vs faces fulfill properties of vision development (ex. contour, not too complex, top heavy)

Depth perception: Development in infants

1 month: blinking in response to looming objects

4 months: size constancy (object is of same size despite changes in distance from eyes)

6-7 months: respons fearfully to the deep side - indication of depth perception and learning that hight is scary (perhaps depth perception at 2-4 months but no fear as no crawling)

Social referencing:

Checking other’s (parent’s) emotion when confronted with a new object or situation.

Vision: Development in older age

In general, deterioration of vision in the elderly.

• Increased intraocular pressure (less light reaches the retina, reduced sharpness of vision - especially in poor lightning).

• Ocular lens: discoloration, swelling, elasticity decreases (presbyopia - aging of the eye, from +- 40 years of age)

• Higher likelihood of visual problems

Age-related decline in:

• Dynamic vision: moving objects to the location of the observer

• Contrast sensitivity: relevant for the perception of forms and shades (ex. stairs)

• Field of view decreases

Older adults have:

• Longer recovery rates for blinding events

• Slower dark adaptation

• Difficulties in weak enlightened environments

Vision in older age: Consequences for everyday life:

• Competence and procedure of activities of daily living

• Leisure activities and interests, often affects also the emotional level

• Life satisfaction

• Mobility and independence

Vision in older age: Adaptation

Changing environment:

• Better illumination of dark areas

• Bigger font size on packages, cash points, …

• Avoidance of blinding and increase of contrast

Compensation tools:

• Magnifying glasses, monitor readers

• Training how to make optimal use of the tools

• Combined visual and cognitive training in relation to car driving