Development
Changes and continuities that occur withtin the individual between conception and death
Processes of Development
Maturation: Biologically-timed unfolding of changes within the individual according to genetic plan
- Influenced by environmental conditions
Learning: Relatively permanent changes in our thoughts, behaviours, and feelings as a result of our experiences
- Acquisition of neuronal representations of new info
Interactionist Perspective
The view that holds that maturation and learning interact during development
- Maturation restricts timeline of learning
- Learning modulates the maturation (development of vision, speech, etc.)
Habituation Procedure
A method of measuring abilities in infants in developmental studies
- Repeatedly presenting infant with same stimulus until habituated, then presenting novel stimuli to see if they react
- Habituation –> Dishabituation
- If dishabituation occurs, infant elicits a reaction that indicates they can discriminate change
Event-related Potentials (ERP)
A method of measuring abilities in infants in developmental studies
- Cap with array of electrodes placed on scalp
- Detects changes in electrical activity across neurons
- Changes in brain activity in specific areas indicate response to certain stimuli
- Visual stimulus results in changes in occipital lobe, auditory stimulus results in changes in temporal lobe
High-amplitude Sucking Method
A method of measuring abilities in infants in developmental studies
- Rate of sucking of pacifier indicates level of preference
- Baseline sucking rate determined
- Stimulus presented and sucking rate increases
- To keep preferred stimulus, infant must suck at increased rate
- To eliminate stimulus, infant must suck at baseline/decrease rate
Preference Method
A method of measuring abilities in infants in developmental studies
- Infant placed in a “looking chamber” and presented with two different stimuli
- Experimenters measure direction infant is looking to determine level of attention
CONS:
- Equal attention could indicate no preference or inability to discriminate
- Therefore, must be done AFTER ability to discriminate is determined
Competence-Performance Distinction
An individual may fail a task, not because they lack those cognitive abilities, but because they are unable to demonstrate those abilities
- Techniques that properly measure variable of interest must be selected
Longitudinal Design
Same individuals are studied repeatedly over some subset of their lifespan
- Accurate and direct comparisons over time
CONS:
- Expensive and time consuming
- Selective Attrition: When some people are more likely to drop out of a study than others making samples non-representative of the OG pop, resulting in biased samples
- Practice Effect: Changes in participants’ responses due to repeated testing rather than natural development of the skills being studied
Cross-Sectional Design
Individuals from different age groups are studied at the same point in time
PROS:
- Faster comparisons between age groups that help researcher formulate likely developmental trends
CONS:
- Cohort Effect: Cannot distinguish age effects from generational effects
- Cannot directly assess individual developmental change… Instead we are making inferences based on trends in group data
Monozygotic and Dizygotic Twins
- Monozygotic Twins: Genetically identical, same sperm and ovum
- Dizygotic Twins: Share ~50% of genes, different sperm and ovum
4 Main Patterns of Genetic Expression
- Simple dominant-recessive inheritance: Pattern of inheritance in which the expression of a trait is determined by a singe pair of alleles (specific form of a gene)
- Homozygous and Heterozygous
- Polygenetic Inheritance: Phenotype is determined by the interaction of multiple genes
- No single gene can account for most complex behaviours
- Codominance: When the expression of a trait is determined equally by two dominant alleles
- Phenotype is a compromise between the two genes
- ABO blood type in humans; A & B are dominant, O is recessive; AB blood type expresses both equally
- Sex-linked inheritance: When the expression of a trait is determined by genes on the X or Y chromosome
- Recessive genes expressed on the X chromosome responsible for colour blindness, hemophilia (a)
- Females have 2 X chr, therefore phenotype of disorder LESS COMMON (chance that other X has the dominant allele: aa or AA or Aa, 25% 75%)
- Males have 1 X chr, therefore phenotype of disorder MORE COMMON (can either be a or A , 50% 50%)
- Y-linked disorders passed from father to son
Canalization Principle
- Within a species, genotype restricts the phenotype to a small number of possible developmental outcomes
- Restricts range of phenotype on basis of species
Range-of-Reaction Principle
- Genotype establishes a range of possible phenotypes in response to different kinds of individual life experiences
- Determines where an individual falls within the range set by canlization
Passive Genotype
The environment parents choose to raise children influenced by their own genes, so it will compliment the child’s genes
- Ex: Couples who are athletic will design an active playroom meshes well with inherited athletic traits
- Most influential early in life as we cannot choose our own environment
Evocative Genotype
The traits that we have inherited affect how others react to and behave towards us
- Genes affect social environment
- Child with difficult temper evokes negative responses (natural temperament affects how others act towards you)
- Influential throughout life
Active Genotype
Genotypes influence the kinds of environment that we seek
- Person with sensation seeking temperament actively chooses environments that satisfy urges
- Most influential later in life as we can choose our own environment
Twin Studies
- Used to unveil relative contributions of genes and environment
- If monozygotic twins are more similar for a trait than dizygotic, different may be due to genetic factors
- Twins that were raised apart (diff environments)
Critical Period
Window of opportunity within develop where particular environmental stimulation is necessary in order to see permanent changes in specific abilities
Implications:
- Likely to affect parental decisions: overstimulating children even before they’re born
- Could affect decisions to adopt
- Public policy on child intervention if they are off typical course of development
The Kitten Experiment
Demonstrates critical period
- Kitten 1 who was visually deprived for the first 6 weeks of life, she is unable to discriminate visual patterns
- Kitten 2 who was visually deprived AFTER her first 6 weeks of life is still able to discriminate visual patterns
- Visual stimulation results in formation of ocular dominance columns (in visual cortex)
Experience-Expectant Brain Growth
- Brains have evolved to expect a certain amount of environmental input, allowing them to develop naturally
- Sufficient simulation of the senses promote normal brain development… no need to provide excess overwhelming stimulation to children
Experience-Dependent Brain Growth
Our brains develop according to our personal experiences
- Reflects subtle changes in brain structure across individuals based on various experiences
Sensitive Periods
Developmental periods during which a specific type of learning takes place most easily
- NOT CRITICAL PERIOD: Still possible for learning to occur after period as passed, just harder…. Less rigid!
- Brain maintains capacity for change and growth to adulthood
- Flexibility in the timing and type of stimulation required for normal development
Quasi-experiment
- Similar to traditional experimental design but lacks random assignment of individuals to groups
- Participants NOT randomly assigned to levels of independent variables
- Cannot control for extraneous variation / CF
- Weakens cause-and-effect conclusions… hence prevalence of correlational methodology in developmental psychology
For example, you are unable to randomly assign age. These types of experiments may have EVs resulting in cohort effect.
