Psychology: Research Methods and Development

• When observers using the same coding scheme disagree on recorded observations, inter-rater reliability is lacking.
• Validity measures whether a test measures what it is supposed to measure.
• A relationship between extracurricular activities and higher grades does not imply causation.

Experiment on Music and Test Performance

• Independent variable: Type of music (Mozart vs. nature sounds).
• Dependent variable: Math test scores.
• A study comparing different age groups at the same time to examine depression symptoms is a cross-sectional research design.
• The habituation method tests if infants can tell the difference between two things by measuring their attention.
• In cephalocaudal development, the head develops first.
• Apoptosis is the scientific term for programmed cell death..
• Cell differentiation is when cells become more specialized.
• The embryonic stage is the most vulnerable to teratogens during prenatal development.
• The effects of teratogens depend partly on the fetus’s genes.
• A fertilized egg successfully implants in the uterus during the germinal stage.
• Newborns get more REM sleep than adults.
• Newborns develop a sense of smell before birth and recognize their own amniotic fluid.
• A newborn hearing two sounds 10ms apart but looking straight ahead indicates they haven’t developed echo suppression yet.
• Phenotype describes observable traits like hair color, eye color, and personality,.
• Heritability measures how much genetic differences explain variation in a trait.
• Greater similarity in a trait among identical twins compared to fraternal twins suggests a strong genetic influence.
• Institutionalization can result in less brain volume, abnormal neural activity, and weaker emotion/cognition skills.
• Early placement in foster care (before age 2) helps institutionalized children with language development.
• Language learning is an example of a critical period; missing early input leads to long-term delays.

Methods to Study Change Over Time

• Cross-sectional studies compare different age groups at one time.
• Longitudinal studies study the same individuals over time.

Cross-Sectional Studies

• Advantage: Quick and cost-effective.
• Disadvantage: Doesn’t track individual changes over time.

Longitudinal Studies

• Advantage: Shows individual developmental changes.
• Disadvantage: Time-consuming and expensive.
• To test if infants can distinguish between cats and dogs, use the habituation method.
• Show images of one animal repeatedly, then introduce a new one to see if infants react differently.
• A teratogen is a substance that can harm a developing fetus.
• Examples of teratogens include alcohol, nicotine, and certain prescription drugs.
• Three factors influence how harmful a teratogen is: dose, timing, and genetic susceptibility.
• An unborn child is most vulnerable to teratogens during the embryonic stage (weeks 3–8), when major organs are forming.
• Newborns preferring stories read to them in utero suggests prenatal hearing and memory.
• Newborns sleep more and spend more time in REM sleep compared to adults.
• Stimulation theory suggests newborns have more REM sleep to help develop the visual system.
• Experience-expectant plasticity is when the brain adapts to expected experiences (e.g., vision).
• Experience-dependent plasticity is when the brain adapts to unique experiences (e.g., learning an instrument).
• A child's phenotype is influenced by genetic predispositions (e.g., height potential) and environmental influences (e.g., nutrition).
• Heritability is the percentage of variation in a trait due to genetic differences among individuals.
• Behavior geneticists test whether a trait is heritable using twin and adoption studies; higher similarity in identical twins suggests a genetic basis.
• A secular trend is a long-term change in a population’s traits over generations.
• Earlier puberty onset is an example of a current secular trend, possibly due to improved nutrition.
• Centration in Piaget’s theory is focusing on one aspect of a situation while ignoring others.
• Egocentrism in Piaget’s theory is difficulty understanding others' perspectives.
• A child thinking a taller glass has more liquid, even if both glasses hold the same amount, is an example of centration.
• A child covering their own eyes and thinking others can’t see them is an example of egocentrism.
• Infants use common motion (objects moving together) and color/texture similarity as cues for object segregation.
• In Piaget’s object permanence test, he hid a toy, and if the baby didn’t search for it, he concluded they thought it disappeared.
• Studies show babies as young as 3.5 months understand objects exist even when hidden.
• The three types of depth perception cues: binocular (develops around 4 months), monocular (5-7 months), and motion-based (birth).
• Researchers test depth perception in infants using the visual cliff experiment.
• Infants hesitate at a "drop-off," showing depth awareness.

Explore inter-rater reliability, validity, and correlation vs. causation in research. Learn about experimental design, developmental psychology, and prenatal development. Understand the impact of teratogens and the processes of cell differentiation and apoptosis.