Psychology Midterm Review
Themes discussed in first half of course
Gene-environment interactions across an individual’s lifespan
Gene-environment interactions across the evolutionary history of a
The study of the nervous system
Development- refers to the changes and continuities that occur within the
individual between conception and death
Maturation- the biologically timed unfolding of changes within the individual
according to the individual’s genetic plan. How this plan unfolds is influence by
specific environmental conditions that shape the genetically determined processes.
Learning- refers to the relatively permanent change in our thoughts, behaviours,
and feelings, as a result of our experiences. Learning processes allow you to acquire
new information and guide optimal strategies to respond to events and stimuli in
Learning processes can be controlled but can also become so practiced as to
become automatic. For example, to look left then right when crossing the street. We
learned this as a child, but as an adult it becomes installed in us to do this before
crossing the street.
Interactionist Perspective- the view that holds that maturation and learning
interact during development. Plays important role in understanding inherited traits,
prenatal development, and how our nervous system develops across a lifespan.
Changes that occur earlier in life are much more dramatic than those occurring
later in life, therefore many researchers who study human development focus on
infancy and childhood.
4 methods of measuring abilities in infants
Habituation Procedure – determines if an infant can detect the difference
between two stimuli.
Process of Habituation Procedure- begins by repeatedly presenting the infant
with the same stimulus, such as tone or a picture, while measuring changes in
physiological responses, like heart rate and breathing, or behavioural orienting
1 responses like head or eye movements. When a novel stimulus is presented, an
infant will initially show a burst of activity. As the same stimulus is repeatedly
presented, the infant’s responses will return to baseline levels. At this point the
infant has demonstrated habituation to the stimulus.
Event related potentials- a measure of the brain electrical activity evoked by
the presentation of stimuli.
To measure event related potentials, 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 measure will evoke changes in the various brain regions of interest.
And so, if you were presenting the infant with a visual stimulus you may
expect changes in activity in the occipital lobe of the brain, an area devoted to
If you were presenting an auditory stimulus, you may expect changes in the
temporal lobe region, an area devoted to auditory processing.
Habituation and ERP provide complementary behavioural and neural measures
to understand an infants sensory interactions with the environment
High-amplitude sucking method- to determine what an infant likes or dislikes.
In this procedure you first measure the baseline-sucking rate for the infant in the
absence of relevant stimuli. During the shaping procedure, the infant is giving
control of the presentation of a stimulus to be tested such as a series of musical
notes. IF she sucks on the pacifier at a faster rate then baseline (means she likes it),
a switch is activated in the pacifier that causes the stimulus to be presented. If the
infant can detect the musical notes and likes what she hears, she can keep the
musical notes playing for longer by increasing her sucking rate & vise versa.
Preference method- another method of measuring what an infant likes &
In this method, the infant is put in a looking chamber to simultaneously look at 2
different stimuli. The researcher can accurately 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 the infants tend to prefer
looking at big patterns with lots of black and white contrasts and prefer looking at
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.
2 Longitudinal Design- a developmental research design in which the same
individuals are studied repeatedly over some subset of their lifespan. In this,
researchers examine the abilities and characteristics of the same individuals
repeatedly over a subset of their lifespan.
There are several disadvantages to longitudinal design
1. Firstly a study is very time consuming, as it covers a persons entire lifespan.
2. Selective attrition- loss of participants in a study such that the sample ends
up being non-responsive of the population as a whole.
3. Practice effects- changes in participant’s responses due to repeated testing.
Cross-Sectional Design- a developmental research design in which individuals
from different age groups are studied at the same point in time.
Advantages of Cross sectional Design:
1. Allows researchers to assess developmental change
2. Relatively less time consuming an expensive; can uncover age differences.
Disadvantages of Cross Sectional Design:
1. Cannot distinguish age effects from generational effects
2. Cannot assess developmental change
3. You are not directly tracking changes with age. Since each person is only
studied at a single time point, you are not really observing what happens as a
When a sperm penetrates an ovum a new cell is formed called a zygote, which
contains 46 chromosomes, 23 from each parent. A chromosome is a threadlike
structure that is made of DNA. Segments of DNA comprise of genes, which provide
the chemical code for development.
Each parent can produce more than 8 million different genetic combinations.
Monozygotic Twins- same sperm and ovum, which formed one zygote and then
split into 2 separate zygotes, genetically identical
Dizygotic twins- come from two different sperm and ova, and start off as two
different zygotes from the moment of conception, share ~50% of genes
Genotype- an individual’s inherited genes. The 46 identical chromosomes in each
of your cells translates into the roughly 30-40000 genes that make up your
Phenotype- the expression of an individual’s genotype in terms of observable
3 Four Patterns of Genetic Expression
Simple dominant- recessive inheritance- a patter of inheritance in which the
expression of a trait is determined by only one allele. One allele is inherited from
each parent. Together this pair of alleles determines the phenotypic expression for a
Homozygous- when two genes have the same effect on the phenotype
Heterozygous- when two genes have a different effect on the gene.
Dominant gene is expressed in the phenotype, and recessive gene is
still in genotype and can pass this gene on to children.
Polygenic Inheritance- when multiple genes are involved in the expression of a
trait. Many traits like height and weight are determined by the interaction of
multiple genes, which adds exquisite complexity.
Codominance- in this situation, two dominant alleles are both fully and equally
expressed to produce a phenotype that is a compromise between the two genes. A
good example is the ABO blood type proteins in humans, in which there are two
dominant alleles (A or B) and one recessive allele (O). When both dominant alleles
are present, instead of expressing one over the other, the offspring expresses both
equally leading to a blood type of AB.
Sex-linked Inheritance- involves genes expressed on the X chromosome.
Remember male =XY & females = XX. This becomes important when you consider
that some recessive genes expressed on the X chromosome are responsible for
disorders like colour blindness or hemophilia. Because females have two x
chromosomes, the phenotypic expression for the recessive allele occurs less
frequently in females. Thus, females rarely express sex linked recessive gene
disorders in there phenotype, but they are often genetic carriers.
One of the most hotly debated issues has been the nature vs. nurture debate- the
extent to which genetics and environmental factors contribute to how a person
At one extreme, some scientists believed that nurture was all-important, and that
a person’s development was largely independent of genetic factors. Ex. Watson
At the other extreme, some scientists believed that who you became was largely
predetermined by inherited genes & that the environment had a minimal effect.
Canalization Principle- Genotype restricts the phenotype to a small number of
possible developmental outcomes.
A classic example is infant babbling. Despite the incredible range of language
cultures that a child may be born into, all infants babble in the same way making
similar sounds; this universal phonemic sensitivity is independent of the
Range of Reaction Principle- genotype establishes a range of possible
responses to different kinds of life experiences.
4 Just as the environment influences the expression of your genes, your genes can
influence the type of environment that you seek out. Three different ways:
1. Passive Genotype/environment correlations: the environment that your
parents choose to raise you in was influenced by their own genes, and so this
environment will likely complement your genes. For example a couple that
are both athletic with good hand-eye coordination and reflexes, when
designing the environment to raise their child, they might focus on an active
playroom with many physical toys. Early in life
2. Active genotype/ environment correlations- our genotype influence the
kind of environments that you seek. For example a person with a sensation
seeking temperament may actively choose environments, which satisfies
these thrill-seeking urges. Develops in childhood and continues to adulthood
3. Evocative genotype/environmental correlations- the way that your
inherited traits affects how others respond to you & is influential throughout
your life span.
Because both types of twins normally develop in the same environment at the
same time, you can assume that if monozygotic twins are more similar for a trait,
than are dizygotic twins the difference is presumable due more to genetic factors.
Monozygotic twins have a higher IQ, which may suggest the degree to which genes,
or environment contribute to a particular trait.
Critical Period- a window of opportunity within an individuals development in
which particular environmental stimulation is necessary in order to see permanent
changes in specific abilities. For examples view slides.
Such studies suggest that without a normal level of environmental stimulation,
the brain may not fully develop some of its functioning to its full potential.
Does more early stimulation= more brain development? Unclear answer
Experience-expectant brain growth- the brain has evolved to expect a
particular level of environmental input, and with this input, our brains develop
normally. Ordinary levels of visual, auditory, and social input, ensure that the brain
Experience-dependent brain growth-which refers to the unique way in which
your brain develops according to your own personal experiences. This type of brain
growth is specific to each individual and reflects the more subtle changes in brain
structure across individuals based on their varied experiences.
Sensitive Periods- brain maintains some residual capacity for change and
growth in adulthood: the fact that our brains develop according to our own personal
experiences. Captures the idea that the brain maintains at some residual capacity for
change and growth into adulthood.
5 Adaptations- are biological traits that help an individual to survive and
reproduce in its habitat. They perform specific functions that make an organism
better suited to its environment.
Adaptations emerge in development as a result of the activation of relevant genes
in interaction with relevant aspects of the environment. They arise through natural
Natural Selection- the differential survival and reproduction of organisms as a
result of heritable differences between them. It was first discovered by Charles
Darwin, and Alfred Russel Wallace, and is one of 4 basic mechanisms of evolution,
the other being mutation, genetic drift, and migration.
Over successive generations, there will be selective transmission of heritable
parental traits. This is because the specific characteristics that are best adapted for
survival and reproduction are going to be reproduced at higher rates.
Stabilizing Selection- selection against any sort of departure from the species-
typical adaptive design… and this sort of selection tends to keep traits stable over
Darwinian Fitness- average reproductive success of a genotype relative to
alternative genotypes. About reproduction
Evolution as a change in gene frequencies over generations
Most of the organisms you typically think about reproduce sexually, as opposed
to asexually, and this involves the fusion of male and female gametes. In sexually
reproducing organism, there is often competition for mates, and natural selection
acts on mate-finding and reproductive behaviours. This is known as sexual
Sexual Selection- the component of natural selection that acts on traits that
influence an organism’s ability to obtain a mate.
For examples & mate selection= view last ten minutes of presentation
Organisms evolved to maximize their fitness and reproductive success.
Evolution acts at the level of genes and those genes that contribute to an
individual’s fitness will consequently get replicated more often, increasing in
frequency in successive generations. Often referred to as the selfish gene.
Table of social behaviors- view lecture??
Altruism- behaviour in which the actor incurs a cost to provide a benefit to a
Not Altruism-foraging/vigilance in groups. Not altruism because actor gains
A group full of altruists will thrive because individuals in that group are regularly
helping one another. But how will the individuals that make up this group do? An
individual that behaves altruistically decreases its own direct fitness by definition,
whereas an individual that behaves selfish won’t.
Eusocial Hymenoptera- includes all ants, some bees & wasps. Most individuals
spend their lives serving the colony without reproducing. How is this possible?
6 The answer comes from an amazingly crucial insight by an evolutionary biologist
named W.D Hamilton. In the 1960’s, Hamilton was troubled by the evolution of
altruism because as he saw it, standard accounts of natural selection could never
favour genes for self-sacrifice. But he realized that the solution was as simple as
recognizing that genes for altruism could be successful if they helped identical
copies of themselves. He introduced this concept in his theory of inclusive fitness.
Direct fitness- is an individuals genetic contribution through its personal
Indirect Fitness- is an individual’s genetic contribution through the
reproduction of close genetic relatives
Direct fitness + indirect fitness= inclusive fitness
This means that you can increase your fitness by helping kin to successfully raise
their offspring sometimes even when doing so has negative effects on your own
direct fitness (case for honey bees and eusocial hymenoptera)
Because of inclusive fitness, natural selection can favour not only behaviours that
increase an individual’s own reproductive success, but also behaviours that increase
the reproductive success of close genetic kin.
Hamilton’s rule- the reproductive benefit to the recipients (B) multiplied by the
probability that the recipients actually have identical copies of the same gene, or
coefficient of relatedness (r ) must be greater then the reproductive cost to the actor
An altruistic behaviour will be favour when br >c, where c is the reproductive
cost to the actor “b” is the reproductive benefit to the recipient and “r” is the degree
of relatedness between the 2 individuals.
Relatedness- probability that actor and recipient share gene in question.
Depends on how genes were inherited.
For example in humans we get 1 gene from each parent, however these copies
are not always identical. The one you inherit from mom may be the same or
different then the one you inherit from your dad.
You have a 50/50 chance of inheriting an identical gene from your parents
Relatedness- full siblings =.50. Half siblings= .25. Aunt/uncle=.25. First cousins
Phenotype matching- an evaluation of relatedness between individuals based
on an assessment of phenotypic similarity. Baboons, rhesus monkeys, golden
hamsters, and Belding’s ground squirrels use this concept.
Direct Reciprocity- refers to situations in which individuals help each other and
both benefit. In some circumstances, individuals who reciprocate acts of generosity
can have a selective advantage over others who do not.
Indirect Reciprocity- occurs when individuals help those who have helped
others. By helping another, you establish a good reputation for yourself and overall