Frontiers Ch. 12 Sep.27.12 8:27 AM
Development over the lifespan
Developmental psychology studies the process of aging. Questions about the influence of nature and
nurture, the existence of critical and sensitive periods, continuity versus discontinuity, and stability
versus change have played a major role in guiding much developmental research.
Four broad issues guide developmental research
o Nature vs.Nurture
To what extent is our developmental the product of heredity (nature)
or the product of environment (nurture)?
How do nature and nurture interact?
o Critical and sensitive periods
Are there specific experiences that are important at particular ages, or
essential to human development?
Critical Period; an age rand in which certain experiences
must occur for development to proceed normally or along a
Sensitive Period; an optimal age range for certain
experiences, but if those experiences occur at another time,
normal development will still be possible (but not according
the social norm timeline)
Is development continuous and gradual, or is it continuous and
gradual, or discontinuous, progressing through qualitatively distinct
o Stabilityvs. Change
Do our characteristics remain consistent as we change? Five different developmentalfunctions;ChangewithAge
Representing (A) abilities present at birth that remain constant across the lifespan; (B) abilities not
present or immature at birth that mature gradually over age; (C) abilities that emerge in stages; (D)
abilities that emerge after birth, peak, and then disappear with age; (E) abilities present early in life
that disappear temporarily and re-emerge later. Examples are given in the text.
A) No changean ability present at or before birth that remains relatively
constant across the lifespan (e.g., the ability to discriminate high- from low-
pitched sounds, or to see objects as distinct from their background: figure-ground
B) Continuous change (continuity)an ability not present, or very immature, at
birth that develops gradually over months or years and then remains constant
over age (e.g., certain types of intelligence). C) Stages (discontinuity)an ability that progresses in stages, with relatively
rapid shifts from a lower level of performance to a higher level (e.g., in motor
development, the shift from rolling, to crawling, to standing, to walking; in
cognitive development, the shift from non-verbal thought to symbolic thinking
D) Inverted U-shapedfunctionan ability that emerges after birth, peaks, and
disappears with age (e.g., separation anxiety; visual acuity across the lifespan).
E) U-shaped functionan ability that is present early in life, disappears
temporarily, and re-emerges later (e.g., newborns turning toward off-centered
sound and stepping with support).
Expl ain how Cross -Sectional, Longitudinal, and Sequential designs differ.
CrossSectional Design-comparing people of different ages at the same point in time
o Administer certain tasks to people of different age groups (10-, 20-, 30-, etc)
and test them only once an compare how well the different age groups
widelyused becausedatafrommay agegroups canbe collected relatively
Atthedifferent agegroups (cohorts)peoplegrewup atdifferent
historical periodsandmay not account for,thus theirknowledge
may not be relevant Longitudinal Design-repeatedly testing the same cohort as it grows older (retesting
every 10 years or so)
Time consuming; and theindividuals may move,dropout ofthestudy,or
SequentialDesign-combination of bot cross-sectional design and longitudinal
o Repeatedly test several age cohorts as they grow older and determine whether
they follow a similar developmental pattern
Mostcomprehensive;butalso themost time-consuming and costly.
Prenatal Period ;approx. 266 days from which we develop from a single-cell
organism barely larger than a pinhead into a complex newborn human
o Germinal Stage-First 2 weeks of development, beginning when one sperm
fertilizes a female egg (ovum, after fertilized it becomes a zygote)
Through repeated cell division the zygote becomes a mass of cells that
attaches to the mothers uterus about 10-14 days after conception
Embryonic Stage; extends from the second week through the eighth week after
conception, the cell mass becomes an embryo
o Located on the uterine wall, the placenta contains membranes that allow
nutrients to pass from the mothers blood to the umbilical cord
Umbilical Cord contains blood vessels that carry nutrients and oxygen
to the embryo, and waste products back from the embryo to the
8 thweek -the heart of the 2cm long embryo is beating, the brain is
forming, the facial features (eyes, etc) can be recognized.
Fetal Stage ; 9 week the fetus forms, lasts until birth
o Muscles become stronger and other bodily systems continue to develop
o 28 weeks; the fetus attains the age of viability (it is likely to survive outside
the womb in case of premature birth
o Behavioral responses and learning begin during the fetal stages.
Genetics & Sex Determination
A females eggs and a males sperm cells each have 23 chromosomes, both unite and
form the zygote which contains half of each (has 23 chromosomes)
o Last chromosome determines the sex. |Female= XX | Male = XY|