PSYC 1101 Introduction to General Psychology

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PSYC 1101Introduction to General Psychology

• Learning Unit 2D
• The Biological Subsystem
• Physical Development Through the Lifespan

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Conception
A single sperm cell (male) penetrates the outer
coating of the egg (female) and fuse to form one
fertilized cell.
Lennart Nilsson/ Albert Bonniers Publishing
Company
Lennart Nilsson/ Albert Bonniers Publishing
Company
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Stages of Prenatal Development

• Zygotic (germinal) Stage Conception to
  approximately 2 weeks
• Less than half of zygotes survive beyond 2 weeks
• Cell differentiation begins at about 1 week
• Stage ends when zygote is implanted in uterine
  wall outer cells become placenta and inner
  cells become embryo

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Prenatal Development
A zygote is a fertilized cell with 100 cells,
which become increasingly diverse. At about 14
days the zygote turns into an embryo (a -embryo
at 40 days and b embryo at 45 days ).
Lennart Nilsson/ Albert Bonniers Publishing
Company
Biophoto Associates/ Photo Researchers, Inc.
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Stages of Prenatal Development

• Embryonic Stage 14 days to Approximately 9 weeks
• Organs Begin to Form and Function
• Fetal Stage 9 Weeks to Birth
• At Approximately 6 months development sufficient
  for a chance of survival
• Fetus is responsive to sound and other
  stimulation

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Prenatal Development
At 9 weeks an embryo turns into a fetus (c fetus
at approx. 60 days and d fetus at approx. 90
days).
Lennart Nilsson/ Albert Bonniers Publishing
Company
Lennart Nilsson/ Albert Bonniers Publishing
Company
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Teratogens

• Substances that cross the placental barrier and
  adversely affect development
• Examples
• Diseases such as rubella, AIDS, syphilis
• Drugs such as heroin, nicotine, alcohol, cocaine,
  some prescription drugs
• Environmental hazards including radiation, lead

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Other Factors Affecting Prenatal Development

• Nutrition
• Stress and Emotional Condition of Mother
• Anoxia
• Delivery Complications

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The Competent Newborn
Infants are born with reflexes that aid survival,
including the rooting reflex that helps them
locate food and the sucking reflex that enables
them to obtain nourishment.
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The Competent Newborn
Crying is an important signals for parents to
provide nourishment. In animals and in humans
such cries are quickly attended to and relieved.
Carl and Ann Purcell/ Corbis
Lightscapes, Inc. Corbis
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The Competent NewbornSocial Reflexes

• Human infants are born preferring sights and
  sounds that facilitate social interaction
• They turn their heads in the direction of human
  voices
• They gaze longer at a face-like image
• They prefer to look at objects 8-12 inches away
  (the approximate distance between a nursing
  infants eyes and its mothers eyes

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Infancy and Childhood
Infancy and childhood span from birth to teenage
years. During these years the individual grows
physically, cognitively and socially.
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Physical Development
Infants psychological development depends on
their biological development. To understand
emergence of motor skills and memory we must
understand the developing brain.
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Developing Brain
The developing brain overproduces neurons.
Peaking around 28 billion at 7 months of prenatal
development, these neurons are pruned to 23
billion at birth. The greatest neuronal spurt is
in the frontal lobe enabling the individual for
rational thought.
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Maturation
The development of the brain unfolds based on
genetic instructions, leading various bodily and
mental functions to occur in sequence standing
before walking, babbling before talkingthis is
called maturation.
Maturation sets the basic course of development,
experience adjusts it . The sequence of
development is (more or less) universal, the
timing of development is affected by experience.
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Motor Development
Infants begin to roll over first followed by
sitting unsupported, crawling, and finally
walking. Experience has little effect on this
sequence.
Renee Altier for Worth Publishers
Phototake Inc./ Alamy Images
Profimedia.CZ s.r.o./ Alamy
Jim Craigmyle/ Corbis
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Maturation and Infant Memory
Earliest age of conscious memory is around 3½
years (Bauer, 2002). Memories are organized
differently after age 3-4 (related to language
development) As the cortex of the brain matures
toddlers gain a sense of self and increased
memory storage capacity. All of these
developments affect memory. Despite absence of
conscious memories there is evidence that some
memories are retained at an unconscious level
Courtesy of Carolyn Rovee-Collier
Amy Pedersen
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Maturation of the Brain

• As the child progresses from infancy through
  childhood, the brain continues to mature in
  response to experience forming new neural
  circuits enabling the child to gain control over
  psychological and physical functions
• These changes in brain structure become evident
  in advances in cognitive development and motor
  control

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Physical Development in Childhood

• During childhood the body grows rapidly and the
  child develops mastery over both psychological
  and physical functions
• This increase in mastery results from the
  interaction between experience (nurture) and
  maturation (nature)

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Physical Development in Adolescence
Adolescence (the period between childhood and
adulthood) begins with puberty (sexual
maturation). Puberty occurs earlier in females
(11 years) than males (13 years). Thus height
in females increases before males.
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Primary Sexual Characteristics
During puberty primary sexual characteristics
the reproductive organs and external genitalia
develop rapidly.
Ellen Senisi/ The Image Works
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Secondary Sexual Characteristics
Also secondary sexual characteristicsthe
nonreproductive traits such as breast and hips in
girls and facial hair and deepening of voice in
boys develop. Pubic hair and hair in armpit grow
in both sexes.
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Brain Development
Until puberty neurons increase their connections,
however, at adolescence selective pruning of the
neurons begin. Unused neuronal connections are
lost to make other pathways more efficient.
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Frontal Cortex
During adolescence neurons in the frontal cortex
grow myelin which speeds up nerve conduction.
Frontal cortex lags behind limbic system
development. Hormonal surges and limbic system
may explain teens occasional impulsiveness.
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Physical Development in Adulthood
The peak of physical performance occurs around 20
years of age, after which it declines
imperceptibly for most of us.
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Middle Adulthood
Muscular strength, reaction time, sensory
abilities and cardiac output begin to decline
after mid-twenties. Around 50, women go through
menopause and men experience decreased levels of
hormones and fertility.
Bettman/ Corbis
Willie Mays batting performance.
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Old Age Life Expectancy
Life expectancy at birth increased from 49 years
in 1950 to 67 in 2004, and to 80 and beyond today
in developed countries. Women outlive men and
outnumber them at most ages.
Gorges Gobet/ AP Photo
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Old Age Sensory Abilities
After age 70, hearing, distance perception, and
the sense of smell diminish, as do muscle
strength, reaction time and stamina. After 80,
neural processes slow down, especially for
complex tasks.
Michael Newman/ PhotoEdit
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Old Age Motor Abilities
At 70, our motor abilities also decline. A
70-year old is no match for a 20 year old
individual. Fatal accidents also increase around
this age.
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Old Age Dementia
With increasing age the risk of dementia (erosion
of mental abilities) also increases. However,
dementia is not a normal part of growing old.
Alan Oddie/ PhotoEdit
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Old Age Alzheimers Disease
Risk of Alzheimers disease also increases with
age. Individuals who are in the early stages of
this disease show more diffuse activity in the
brain than normals of the same age. Alzheimers
affects memory, reasoning, personality and
eventually control of physical functions.
Susan Bookheimer
At risk Alzheimer
Normal
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Alzheimers Disease

• Alzheimers disease is related to a loss of brain
  cells and deterioration of neurons that produce
  acetylcholine
• Active non-obese individuals and those with an
  active challenged mind including educated
  active readers are at less risk for Alzheimers
  disease