Unit 2 – Infancy
Lesson 3: Physical and Cognitive Development in Infancy: the First Two Years
Learning Objectives
1. Differentiate the two primary
... [Show More] growth patterns.
- When you’re born you weigh 3.4Kg and are 48cm long. By age 2 you’re 3x your
weight and 2x your height
- There are 2 major growth processes that begin prenatally
1. Cephalocaudal pattern of growth: Growth from the head downwards (head
develops first followed by what is more down)
2. Proximodistal pattern of growth: growth from the inside of the body towards the
outside (trunk of the body develops faster than the arms or the legs)
2. Discuss infant brain development, including the concepts of synaptic pruning and
plasticity.
- Given the cephalocaudal pattern of growth, the brain develops very quickly in the 1st
2 years of life
- The brain goes form 2500 synapses @ birth 10 000 @ age 2
- Myelination also happens to increase impulse travel rates
- Synaptic connections that are constantly activated get strengthened. Those that don’t
are discarded by synaptic pruning
- The potential for systematic change w/i a person to fit their environment is called
plasticity. The human brain is extremely plastic during infancy
3. Describe the importance of experience and sleep in brain development.
- 2 processes related to early experience and brain development
1. Experience-expectant processes: brain development that occurs based on
environmental experiences that all members of the species typically encounter.
(e.g. for normal visual and auditory development one must see light and hear
sound)
2. Experience-dependent processes: brain development that occurs based on unique
environmental stimuli shared by only individuals in particular environmental
circumstances (e.g. repeated exposure to the sounds of a language helps the child
create those sounds)
- Most brain development occurs during sleep. Where infants sleep 10 – 19 hours. But
they wake up frequently most notably due to immature brain development
- Infant sleep-wake cycles are controlled by the brain-stem which needs to be trained
- Rapid eye movement (REM) sleep: sleep that aids in learning and memory
consolidation. Newborns spend 50% of sleep on REM sleep. By age 2 it’s 20-25%
- The other category of sleep is non-REM sleep (NREM).
4. Describe the newborn reflexes and development of gross and fine motor skills.
- A reflex is a quick and simple neural pathway that involves few neurons of the PNS
- Some reflexes are for survival while others disappear over time. They include
1) Planter grasp: flexing of the toes when applied pressure. Appears 28 wks
gestation and is integrated @ 9 mo
2) Babinski (planter response): Fanning out of toes when outside of the foot is
stimulated. Appears birth to 12-18 mo and is integrated after walking
3) Moro: shoulders pull back and fingers, elbows and wrists extend after head
and neck drop to the other hand. Appears 28 wks gestation and integrated at 5-
6 mo
4) Palmar grasp: Infants flex around the finger. Appears 10 wks gestation and
integrated 4-6 mos
5) Rooting and sucking: infant turns head with mouth open twds finger and
attempts to suck on finger. Appears 28 wks gestation, integrated 3 mos
6) Stepping or walking: alternating, rhythmical, coordinated steps. Appears 37
wks gestation, integrated 2 mos
7) Crawling: infant pulls legs underneath abdomen and pushes forward. Appears
at birth, integrated 3-4.
8) Tonic neck: infant adopts fencer position when on the back. Appears at birth,
integrated 6-7 months.
- Gross motor skills: skills that use the large muscle groups such as those in the legs or
arms
- Fine motor skills: skills that use smaller muscle groups such as those of the fingers
and eyes
- Most newborn movements are involuntary responses to sensory stimulation. By the
end of infancy they have developed many gross and fine motor skills due to
integration of the muscular and nervous system
5. Discuss Piaget’s sensorimotor stage and associated sub-stages.
- Sensorimotor stage: Piaget’s first stage of cognitive development, in which infants
develop from reflex-driven organisms to more complex and symbolic thinkers
- From one stage to another requires assimilation and accommodation and requires
schemes (mental structures that help us organize and process information)
- Object permanence: infants develop a concept of objects that goes beyond immediate
sensory contact (remembering a hidden toy)
- Sub-stages
1. Reflexes (birth – 1 mo)
2. Habits and repetition (1 – 4 mo) doing reflexive habits without stimulation
3. Actions with objects (4 – 8 mo) doing things with objects (e.g. Grasping)
4. Coordination of schemes and intentional behaviour (8 – 12 mo)
5. Using objects in novel ways (12 – 18 mo)
6. Symbolic thought (18 – 24 mo) e.g. think about a toy even if it’s not present.
If an infant can’t do it’s A not B error
6. Describe the development of memory and the methods used to measure memory.
- It is very difficult to measure memory in infants
- There are 2 kinds of memory
1. Implicit memory: repetition of a behaviour, such as leg movement to make an
object move, that occurs automatically and without apparent conscious effort
2. Explicit memory: repetition of a behaviour that shows a clear, observable,
conscious effort to recall an event such as when an infant imitates at a later time a
behaviour seen earlier
- Imitation requires infants to internalize a behaviour and then repeat it. They need to
learn deferred imitation which occurs at 6-7 months which is the ability to imitate
when there is a delay in imitation [Show Less]