Prenatal development and infancy

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Prenatal development

Prenatal development:

  • Zygote: first 2 weeks of development prior to implantation in the uterine wall
  • Embryo: 3rd-8th week of development - aperiod of rapid growth and differentiation of structures and organs
  • Foetus: 3rd to 9th month of development. All major systems are present; these continue to grow and develop
  • Neonate: the newborn arrives into the outside world

Preformationists in the 17th century believed that the human form (body and mind) was complete before conception. Development to them was just a matter of increasing size. They argued that the full human form was specified in sperm cells.

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Teratogens

It's clear from numerous environmental influences that prenatal development is far from being a straightforward and maturational process

Teratogen: an agent or factor which causes birth defects via a toxic effect on an zygote/embryo/foetus. Examples of teratogens:

  • Drugs (legal, illegal, prescription)
  • Environmental toxins
  • Malnutrition in the mother
  • Disease

Specific teratogens have specific periods during which they have an effect. The embryonic period (during which there's particularly rapid growth) is the most vulnerable to teratogenic influence. Susceptibility to teratogens varies with the developmental stage at the time of exposure to an adverse influence. It also depends on the genotype of the embryo.

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Learning + senses in the womb

Sense of smell and taste are among the first to develop in utero. First responses are at 4-8 weeks gestation.

  • Schaal et al (2000): newborns whose mothers ate garlic during pregnancy showed less aversive responses to garlic in the first days of life
  • Menella et al (2001): infants weaned on cereal mixed with carrot juice preferred this if their mother had drunk carrot juice during pregnancy
  • As a foetus grows inside the womb, it can hear sounds from the outside world and understand them enough to retain memories of them after birth. Sound-processing parts of their brain become active in the last trimester of pregnancy
  • A 1988 study suggested that newborns recognise the theme song from their mother's favourite soap opera
  • Partanen, Kujala, Näätänen, Liitola, Sambeth & Huotilainen (2013): gave expectant mothers a recording to play several times a week during their last few months of pregnancy, which included a made up word "tatata" repeated many times interspersed with music. When the babies were tested after birth, these infants' brains recognised the word (showing enhanced brain activity) and its variations, while infants in a control group did not
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Neonates perception

William James: "the baby, assailed by eye, ear, nose, skin and entrails at once, feels it all as one great blooming, buzzing confusion"

Newborns are much more competent perceivers than William James gave them credit for. Infants and newborns perceive a somewhat coherent world through multiple senses. Despite being relatively helpless, they quickly absorb information about their physical and social environments.

Neonatal reflexes

  • sucking
  • rooting
  • respiratory occlusion
  • stepping
  • moro reflex
  • grasping
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Early social behaviours

Researchers disagree over whether all newborn behaviours are mindless reflexes, or whether purposeful behaviours exist in the first few months. Early social behaviours are similarly controversial - are they purposeful or simply reflexive?

  • Smiling: babies smile just after birth. Initial smiles are spontaneous and not always elicited by social stimuli. They typically only include the mouth, not the eyes. Later (around 3 weeks), babies learn to smile in specific situations - through a process of reward for the initial spontaneous smiles?
  • Face and gaze responses: Johnson et al (1991) - showed newborns only 30 minutes old would track face-like stimuli further than scrambled face stimuli. This orienting reflex helps infants start to learn about other people by directing them towards the relevant information. Newborn infants prefer to look at direct gazing faces than averted gaze faces (Farroni et al, 2002)
  • Early social transactions: newborns interactions are characterised by burst-pause in breastfeeding and vocalising. It is unclear whether this represents intentional turn-taking or whether its a simple adaptation which allows parents to scaffold speech
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Piaget's theory

Piaget's (1936) theory of cognitive development explains how a child constructs a mental model of the world. He regarded cognitive development as a process which occurs due to biological maturation and interaction with the environment.

Piaget's four proposed stages of cognitive development:

  • Sensorimotor stage (birth to 2 years): main achievement of this stage is object permanence - knowing an object still exists even when it is obscured. It requites the ability to form a mental representation of the object
  • Preoperational stage (2-7 years): during this stage, young children can think about things symbolically. This is the ability to make one thing - a word or an object - stand for something other than itself. Thinking is still egocentric, and the infant has difficulty taking the viewpoint of others
  • Concrete operational stage (7-11 years): marks the beginning of logical/operational thought. The child can work things out internally. Children can conserve number, mass, and weight in this stage. Conservation refers to the understanding that something stays the same in quantity even though its appearance changes
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Piaget's theory continued

  • Formal operational stage (11+ years): during this time, people develop the ability to think about abstract concepts, and logically test hypotheses

Piaget viewed intellectual growth as a process of adaptation (adjustment) to the world. This happens through:

  • Assimilation: using an existing schema (building block of a cognitive model, enabling us to form mental representations of the world) a to deal with a new object or situation
  • Accommodation: existing schema doesn't work and needs to be changed to deal with a new object or situation
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