Pre- and post-natal development

Question 1

How does pre-natal physical development differ from other stages?

Answer 1

Rather than being continuous/subtle it occurs in a sequence of stage-like changes e.g. zygote and embryo are drastically different in terms of structural form and interactions with world
Developmental stages are uneven, rate of growth varies at different times, subsystems develop at different rates and we also see periods of regression which reflect periods of reorganisation

Question 2

What is the first stage of pre-natal physical development?

Answer 2

Germinal stage (first two weeks after conception)
Sperm has penetrated egg and zygote forms which undergoes repeated cell division to form a BLASTULA (cells originally undifferentiated stem cells but by end of stage they have differentiated)
Blastula implants into wall of uterus at end of this stage

Question 3

What happens during the embryonic stage of development?

Answer 3

3-8 weeks after conception, period after implantation, during which all of the major organs and structures within the growing mammal are formed

Cells rapidly differentiate and migrate, and cell structures become more organised –> distinct qualitative change and now an embryo - major organs, heart starts to beat, eyes and limbs visible

Question 4

Why is the embryonic stage risky?

Answer 4

Rapid growth brings risk from environmental hazards which can trigger cascading consequences:
Disease - e.g. rubella can cause blindness and brain damage, but risk decreases with increasing months
Drugs e.g. Thalidomide has most severe consequences when administered in this phase
Maternal distress e.g. extreme anxiety and depression can cause low birth weight

Question 5

What is the foetal stage of development characterised by?

Answer 5

Lasts about 7 months, from 9 weeks after conception until birth
Organism is now recognisably human and starts growing in height and weight
No new development occurs but rather organs continue growing and becoming defined, and NS grows considerably - head grows to 30% of total body volume
Spontaneous movement able to be felt by mother - brain is starting to control actions but not conscious yet

Question 6

What is the period of quiescence?

Answer 6

Around week 17 activity stops - believed that brain function gets reorganised and higher centres begin controlling behaviours which were previously controlled by lower structures

At week 24 activity begins again and we can see much finer motor control now, actions such as thumb sucking which require a great deal of coordination

Question 7

How does the vestibular system develop?

Answer 7

Begins to function around 20 weeks gestational age and is fully functional at birth
Allows foetus to sense which way is “up”, and changes in mother’s position - system measures inertial forces on the head

Question 8

What is known about the development of vision?

Answer 8

Eyelids closed until week 26 but foetus can sense light on mother’s abdomen - moves and increases HR

Studies of premature babies show us that around 31 weeks it is possible for them to track a moving target side to side (foetus of same age should be able to do the same)

Question 9

What is auditory development like?

Answer 9

Can respond to sound from around 20 weeks (head and arm movements in response to sound)
Sound energy sensed as motion in fluid via cutaneous sensors - means foetus can only detect LOUD external sounds as mother’s body attenuates sounds and heart beat masks them
Speech of mother conducts well
Initially foetal responses found only to low frequencies (250-500Hz) but range expands as foetus matures
Proper functioning of auditory system at around 30 weeks

Question 10

How did Decasper and Fifer demonstrate that foetuses are able to learn?

Answer 10

Foetuses learning to recognise mother’s voice before birth - mother read story aloud frequently during final stages of pregnancy
Preferential sucking for playback of story read by mother rather than a stranger
Learning mother’s voice is arguably an innate ability

Question 11

What did Fifer and Moon demonstrate?

Answer 11

New-borns PREFER sound of mother’s voice filtered as it sounded in uterus, rather than natural voice sounds
Provides further evidence that foetuses are able to discriminate sounds

Question 12

What did Moon, Panneton-cooper and Fifer suggest regarding language?

Answer 12

Foetuses can learn the sound of their mother’s language - 2-day old infants preferred when a stranger spoke in mother’s language rather than a foreign one

Question 13

What did DeCasper and Spence find evidence of?

Answer 13

Foetus can learn speech sounds of a particular utterance - mothers read a story aloud twice a day for last 6 weeks of pregnancy
2 days after birth infant could listen to a stranger read same or different story, and showed preference for same story
Indicated that foetuses can experience and recognise their mother’s speech sounds and pre-natal auditory experiences can influence post-natal auditory preferences

Question 14

What is birth like?

Answer 14

Around 36-40 weeks, and brings major environmental changes such as potential hazards (disease, extremes of temp, lack of constant nutrients), increase in range of available stimuli and social changes

Question 15

What are 2 physical attributes of new-borns?

Answer 15

Reflexes - e.g. sucking, tonic neck reflex (fencer position - brings hands to child’s attention providing precursor to hand-eye coordination and assisting development of body ownership and sense of agency, should disappear after 6 months)
Brain - 100 billion neurons but connectivity less than in adults (connections promoted through interactions with world); feedback from activity in moving/feeling promote NS development

Question 16

What are the visual attributes of a new-born like?

Answer 16

Poor acuity compared to adults
Limited field of view (60 degrees horizontal, 20 degrees vertical)
Focal length fixed around 21cm i.e. no lens flexibility (distance from mothers face when feeding so evolutionarily advantageous)
No binocular depth perception

Question 17

Why are the limited capacities of newborns not considered deficits?

Answer 17

They are suitably adequate to meet needs of the stage - functional to keep life as simple as possible, so infant only focuses on key information

Question 18

What did Fantz demonstrate regarding newborn vision?

Answer 18

Prefer faces to other stimuli - presented with real face, scrambled face-like features, or simply a black/white control
Infants focused longer on the face - evolutionarily important to have an innate preference for faces due to relation to attachment formation

Question 19

What are 3 other aspects of newborn sensory/perceptual attributes?

Answer 19

Audition - auditory system fairly well developed and various characteristics of mothers speech has been learned in-utero
Olfaction - can differentiate smell of mother’s milk from that of others, and PREFERS mothers milk; also prefers chocolate to rotten eggs without prior experience
Gustation - can tell difference between sweet and sour, showing aversion to sour

Question 20

What are 3 necessary social interactions for a newborn?

Answer 20

Sucking (this stops crying too as silence rewards caregiver)
Orientation towards other people (faces and human speech more than generic stimuli)
Learn different social stimuli e.g. voices

Question 21

How do newborns demonstrate innate capacities for expressing and responding to emotions?

Answer 21

Universal expressions have been identified including happiness and anger
New-borns will cry in response to prolonged crying of other babies

Question 22

What was thought for a time and what studies investigated this?

Answer 22

That infants could imitate facial expressions, an effective way to learn quickly about the emotions of others and learning how to respond
Meltzoff and Moore - new-borns seemed to mirror adult faces; but things like sticking out tongue thought to be a random and natural response to general excitement rather than imitation
Oostenbroek et al - no evidence for innate facial gesture imitation, showing that new borns do act at random (Piaget believed imitation a sophisticated skill that only begins later at around 9months)

Question 23

How did Chess and Thomas classify infant temperaments?

Answer 23

Easy - Behaviour regular, cheerful, adaptable to change
Difficult - Irregular behaviour, responds negatively to change
Slow to warm up - inactive and withdrawn

Question 24

What did Thomas and Chess demonstrate regarding difficult temperaments?

Answer 24

Difficult babies were more active foetuses, and are at risk of later behavioural problems
Difficult temperaments correlated with behavioural maladjustment at 5yrs in American middle class individuals but not in immigrant working class

Question 25

What was suggested as an explanation for Thomas and Chess’s findings?

Answer 25

Cultural differences in child-rearing of difficult babies - American care-givers less likely to respond to difficult babies with sensitivity and patience