Development I & II
Introduction to PSYCH 1XX3
- Gene environment interaction across an individual's life span
- gene-environment interactions across the evolutionary histry of a species
- the study of the nervous sytem
- and the neural basis of thought and behaviour
You will explore how these biological foundations interact with the environment to shape
your sensory systems and behaviours critical to survival.
Introduction to Development
Development = Refers to the changes and continuities that occur within the individual
between conception and death.
----> Developmental psychologists not only interested in how you change over time, but
also in how you stay the same.
2 Different Processes which lead to developmental change:
Maturation = The biologically-timed unfolding of changes within the individual: how the
plan unfolds is infulenced by specific environmenal conditions that shape the genetically-
Learning = The acquisition of neuronal representations of new information
- A lifetime of experiences leads to the development of relatively permanant enduirng
changes in your thoughts, feelings and behaviour.
- Learned processes can be controlled but can also become so practised as to become
- Ex. Crossing roads in different countries
The view that holds that maturation and learning interact during development.
Emphasizes that most of your development changes reflect the interaction of maturation
- Plays an imp role in understanding inherited traits, prenatal development, and how our
nervous system develops across a lifespan.
Maturation & Learning
It's obvious how maturation can affect learning: Some essential systems must be in
place before learning proceeds.
Less obvious that learning can affect maturation: Without some minimal level of input to
learn from the outside world, maturation will be absent or delayed. Learning allows us to acquire new thoughts, behaviours, and feelings.
Be sure to differentiate between changes caused by learning, and changes caused by
Note, development and maturation NOT the same thing.
Many researchers who study human development focus much more on changes that
occur in infancy and childhood compared to any other time in the lifespan. This is bc
changes that occur in earlier in the life are much more dramatic than those occuring later
Measuring Abilities in Infants:
1. Habituation Procedure = To detect if an infant can detect the difference between two
[Tests infant's basic sensory capabilities]
Can be used for a variety of stimuli: diff sounds, pictures, and touch sensations
Begins by repeatidly presenting the infant with the same stimulus (Ex. Tone or a picture)
while measuring changes in physiological responses, like heard rate and breathing, or
behavioural orienting responses.
When a novel stimulus is presented, an infant will initially show a burst of activity. As the
same stiumulus is repeatidly presented, the infant's responses will return to baseline
At this point, the infant has demonstrated habituation to the stimulus.
Habituation = a decrease in responsiveness to a stimulus following it's repeated
Dishabituation = an increase in the responsiveness to a stimulus that is somehow
different from the habituated stimulus
2. Event-related potentials (ERP) = A measure of the brain electrical activity evoked by
the presentation of stimuli
[Neural measures which coincide with the behaviorial events observed]
A special cap with an array of electrodes is carefully placed on the scalp.
These sensitive electrodes can detect changes in electric activity across a population of
neurons in the brain.
The particular behaviour being measured will evoke changes in various brain regions of
interest. And so, if you were presenting the infant with visual stimulus, you may expect
changes in activity in the occipital lobe of the brain, an area devoted to visual
If you were presenting an auditory stimulus, you may expect changes in activity in the
temporal lobe region, an area devoted to auditory processing.
*Together both Habituation + ERP provide complementary behavioural and neural
measures to understand an infant's sensory interactions with the environment* BUT....
how do you ask an infant what he/she likes or dislikes?
3. High-amplitude sucking method = Measures sucking behaviour of infants by a special pacifer.
[Infants can control their sucking behaviour to some extent]
You first measure the baseline sucking rate for the infant in the absence of relevant
During the shaping procedure, the infant is given control over the presentation of a
stimulus to be tested such as a series of musical notes.
If the infant sucks on the pacifer at a faster rate than baseline, a switch is activated in the
pacifer that causes the stimulus to be presented. If the infant can detect the musical
notes and likes what she she/he hears, she can keep musical notes playing for longer by
increasing he sucking rate.
But if the infant doesnt like the sounds, she can stop sucking sooner to end the
4. Preference method = Measuring what an infant likes/dislikes
The infant is put in a looking chamber to simutaneously look at two different stimuli. The
researcher can accuratly measure the direction that the infant is looking to tell if more
attention is being directed to one stimulus over the other.
Using this procedure, researchers have found that infants tend to prefer looking at big
patterns with lots of black and white contrasts and prefer looking at faces.
Inferences & Assumptions
Competence-Performance Distinction = An individual may fail a task not because they
lack those cognitive abilities, but bc they are unable to demonstrate those abilities.
Researchers may use a research technique that does not properly measure their
variable of interest, given their subject pool. Introduction to Developmental Research Methods
Developmental studies are often concerned with repeated measures over time.
2 Different Types of developmental research designs:
1) Longitudinal Design = A developmental research design in which the same
individuals are studied repeatedly over some subset of their lifespan.
Researchers examine the abilities and characteristics of the same individuals repeatidly
over a subset of their lifespan.
- Allows researchers to assess developmental change
- You can track each person over time as they develop
- And thus uncover any inks b/ween how they did early in life with how they did later in
life . Find patterns that are common to all ppl.
Example: Memory of Numbers
a) Expensive & Time consuming (Takes a looong time...)
b) Selective Attribution:
o Loss of participants (Some may quit, become unfit to continue or die) leaving a
fundamentally diff sample at diff time points. Sample ends up being non-responsive of
the population as a whole.
c) Practice Effect:
o Subjects may improve performance based on prior exposure alone, rather than
on natural development over time of the skills being studies. Changes in partipcipants'
reponses due to repeated testing.
These problems mean that the longitudinal study is used less frequently in the real
2) Cross-Sectional Design = A developmental research design in which individuals
from different age groups are studied at the same point in time.
No need to be tracked over the span of many years.
- Allows the researcher to formulate some likely developmental trends, such as memory for numbers improves into early adulthood and then decreases slowly as you age
- Relatively less time consuming and expensive; can uncover age differences
Example: Memory for numbers
- Cannot distinguish age effects from generaional effects. Different ages were exposed
and experienced to different things, everyone is different.
- Cannot directly asses individual developmental change
- Since each person is only studied at a single timepoint, you are not really observing
what happens as a person ages, and instead making inferences on trends in group data
A final alternative is to combine the longitudinal and cross-sectional designs. This
combines the strongest and weakest features of both design types in one.
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Introduction to Hereditary Transmission
Zygote = Sperm + Ovum containing 46 Chromosomes (23 from each parent)
Chromosome = Threadlike structure that is made from deoxyribonucleic acid (DNA)
Genes = segments of DNA which provide the chemical code for development
Results from the Human Genome Project have estimated that our chromosomes
contain between 30 000 to 40 000 genes, that's only about 1/3 more than the simple
roundworm C. elegans
The zygote doesn't remain a single cell for long; it quickly divides at an exponential rate,
growing from two cells to four cells, to 16 etc until you end up with billion of different cells
each with he same 46 chromosomes inherited at conception.
Each parent can produce more than 8 millin different genetic combinations from this sperm or her ova. So, this means that any given couple, could, in theory, produce 64
trillion genetically distinct offspring
Exception to this theory is when parents have identical twins:
1) Monozygotic Twins (MZ): (Identical Twins) Genetically identical bc they come from the
same sperm and the ovum which formed one zygote, and then split into two different
2) Dizygotic Twins (DZ): (Fraternal Twins) They come from two different sperm and ova,
and start off as two different zygotes from the moment of conception.
Are as genetically similar as non-twin siblings (sharing 50% of their genes, on average).
Male determines the gender of the child.
We all have 23 pairs of chromosomes, including 22 autosomes (similar in males and
It is the 23erd pair of chromosome which determines a person's gender.
A female will carry two X chromosomes, while a male will carry an X and a Y
Meaning that a mother always passes an X chromosome, whi