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Strengths and Weaknesses of Research Designs
Design Description Strengths Weaknesses
CorrelationalDesign
Researcher sees if changes in one variable are accompanied by systematic changes in another variable.
Researcher manipulates one of more independent variables to observe the effects on the dependent variable(s).
Experiment conducted in real-life, naturalistic settings.
Assignment of participants to groups is determined by their natural experiences
ExperimentalDesign
Quasi-experiment
Field Experiment
Useful when conditions do not permit the manipulation of variables.
Can isolate cause-and-effect relationships.
Can isolate cause-and-effect relationships; behaviors are observed in natural settings.
Takes advantage of natural separation of children into groups.
Cannot determine cause-and-effect relationships.
May not yield information about real-life behaviors.
Less control over treatment conditions.
Factors other than independent variables may be causing results.
In-depth observation of one or a few children over a period of time.
Single-CaseDesign
Do not require large pool of participants.
Ability to generalize to the larger population may be limited.
• Trust vs. Mistrust
• Autonomy vs. Shame and Doubt
• Initiative vs. Guilt
• Industry vs. Inferiority
• Identity vs. Role Confusion
• Intimacy v. Isolation
• Generativity vs. Stagnation
• Ego Integrity vs. Despair
ERIKSON’S PSYCHOSOCIAL STAGES
Birth – 1 year
1 - 3 years
3 - 6 years
6 - 12 years (Latency Period)
12 - 19 years (Adolescence)
19 – 25 years (Early Adulthood)
25 – 50 years (Adulthood)
50 years and older
PIAGET’S COGNITIVE STAGES
Sensorimotor
Preoperational
Concrete Operational
Formal Operational
Birth - 2 years
2 – 7 years
7 – 11 years
11 years - adulthood
Child develops schemes primarily through sense and motor activities
Child can think symbolically; holds egocentric view of the world
Child becomes able to manipulate logical relationships among concepts but only by generalizing from concrete experiences
Child is able to deal with abstractions, form hypotheses, solve problems systematically
The humanbody contains100 trillioncells.
There is anucleus insideeach humancell (except redblood cells).
Each nucleuscontains 46chromosomes,arranged in 23 pairs.
Onechromosomeof every pair isfrom eachparent.
Thechromosomesare filled withtightly coiledstrands ofDNA.
Genes are segmentsof DNA that containinstructions to makeproteins— thebuilding blocksof life.
Cell nucleus with a pair of chromosomes
Chromosomes split and replicate to producetwo identical pairs
The pairs separate, and the cell divides
Each daughter cell now has a pair of chromosomes that is identical to the original pair
The Process of Mitosis
The Germinal Stage of Prenatal Development
Zygote Implantation of the Embryo
Fallopian tube
Ovary
Uterus
Cervix
Vagina
Embryo joinedto uterine wall
Ovary
Blastocyst
Fallopian tube
Full termFetal period (in weeks)Embryonic period (in weeks)
3820 361612876543
Central nervous system
Heart
Period when majorabnormality occurs
Leg TeethArm
Eye
EyeHeart
Brain
Ear Palate Ear
External genitalia
Central nervous system
Heart
Arms
Eyes
Legs
Teeth
Palate
Period when minor defect orabnormality occurs
External genitalia
Ear
Spine
BladderPubic boneCervixVagina
Coccyx Rectum
Potential width of birth canal
The baby in the uterus before labor Water about to break (The baby's head now rests inside the cervix)
Transition: The baby in the birth canal
The baby about to be born The head rotates sideways after it emerges The delivery of the placenta
STAGE 1
STAGE 2 STAGE 3
InRev1The Apgar Scale
Score
0Characteristic
Heart rate
Efforts to breathe
Muscle tone
Skin color
Reflex irritability
Source: Apgar (1953)
1 2
Absent
Absent
Flaccid,limp
Body pale or blue
No response
Less than 100 beats per minute
Slow, irregular
Weak, inactive
Body pink,extremities blue
Frown, grimace
More that 100 beats per minute
Good; baby is crying
Strong, active motion
Body and extremities pink
Vigorous crying, coughing, sneezing
2 months(fetal)
5 months(fetal)
Newborn 2 years 6 years 12 years 25 years
Body Proportions, Fetal Period Through Adulthood
The Episode of the Strange Situation
Number of Episode Persons Present Duration Brief Description of Action
1
2
3
4
5
6
7
8
Mother, baby, and observer
Mother and baby
Stranger, mother, and baby
Stranger and baby
Mother and baby
Baby alone
Stranger and baby
Mother and baby
30 seconds
3 minutes
3 minutes
3 minutes or lessa
3 minutes or moreb
3 minutes or lessa
3 minutes or lessa
3 minutes
Observer introduces mother and baby to experimental room, then leaves.
Mother is non-participant while baby explores; if necessary, play is stimulated after 2 minutes.
Stranger enters. Minute 1: stranger silent. Minute 2: stranger converses with mother. Minute 3: stranger approaches baby. After 3 minutes mother leaves unobtrusively.
First separation episode. Stranger's behavior is geared to that of baby.
First reunion episode. Mother greets and comforts baby then tries to settle him again in play. Mother then leaves, saying bye-bye.
Second separation episode.
Continuation of second separation. Stranger enters and gears her behavior to that of baby.
Second reunion episode. Mother enters, greets baby, then picks him up. Meanwhile stranger leaves unobtrusively.
aEpisode is curtailed if the baby is unduly distressed.bEpisode is prolonged if more time is required for the baby to become involved in play.Source: Campos et al., 1983.