lecture notes Flashcards
correlation
strength of the association between two variables
- vale (r) can range from -1.0 to 1.0
- value of 0.0 means its not correlated
- closer to 1 or -1 the stronger the correlation
- or - determines direction
correlation does not equal causation
- relationship may be due to a third variable
what’s the solution to determine causal relationships?
“true” experiments
- random assignment to different conditions
- pre-existing differences between people recruited for the different groups in your experiment will be randomized and “wash out” - control over what is experienced
- good experimental design will have people in different conditions experience the exact same conditions, except for a manipulation
reliability
The degree to which a given
measure is consistent with
each measurement.
- Interrater Reliability
- Test-Retest Reliability
validity
The degree to which a given
measure is capturing the
construct it is proposed to
be measuring.
- Internal Validity
- External Validity
a measure can be reliable
but not valid, but a measure can only be valid if it is reliable
contexts for collecting data
- interviews
pros
- provides insight into subjective experiences of individuals
- technological advancements making this more feasible
cons
- time consuming; less feasible to administer on larger scales
- generally low interrater reliability
- questionable utility for predicting future behaviours
contexts for collecting data
- naturalistic observation
pros
- provides insight into “real world” behaviours
- technological advancements making this more feasible
cons
- time consuming; less feasible to administer on larger scales
- experimenter presence disrupts “natural” environment
contexts for collecting data
- LENA device
- captures vocalizations in home
- special algorithms used to analyze speech patterns and non-speech vocalizations
- number of words spoken near the child
- number/length of speaking turns
- time spent in activities (TV; car rides; sleep; play)
how can we study the development of a child in a laboratory experiment?
- cross- sectional: recruit different age groups
- longitudinal: follow same individuals over time
- microgenetic: focused on studying children at developing times. - longitudinal
cross-sectional designs
- compare children from different age groups on same measure
- however, must consider validity of measure across age groups
- doesnt allow you to track individual differences over time
longitudinal designs
- get a measure from the same group of children over time
- address how individual differences change through lifespan
- difficult to follow children over time; very time consuming (may be more difficult to get grant funding over time)
longitudinal designs interventions
- leverages strengths of longitudinal design and experimental control
- randomized control trials (RCTs): randomly assign participant to a group that receives a treatment or to a control group
microgentic designs
- study a developing process at the age it is proposed to change
- similar to a longitudinal design, but shorter period
- elucidates the mechanisms of change
- allows for analyzing individual differences in change
- over shorter period of time
high-amplitude sucking
- pacifier connected to computer
Common devo. DVS (measures)
- high-amplitude sucking
- preferential looking
- normative assessments
4, neuroimaging
a) structural (MRI, DTI)
b) functional (EEG, fMRI)
High amplitude sucking
aka. non-nutritive sucking
✴Pacifier connected to computer
✴Measures changes in air pressure
that occur with sucking
✴Sucking rate reflects level of
interest in given stimuli
✴Increased sucking rate with
increased interest
✴Bored infants show much
decreased sucking rate
✴Successful method for studying
infants as young as 8-hours-old
✴Present a sound every time infant increases sucking
rate beyond a given threshold (e.g. 80% increase)
✴If sucking rate increases in order to listen to a certain
sound, infant prefers the sound (i.e., speech)preferential looking
✴Looking time at an object equated to preference
✴When presented with similar stimuli, longer looking at one than the other indicates ability to discriminate
Uses: Eye-tracking Cameras
Head-Turn Preference
✴Similar to preferential looking, but with sound stimuli
✴Assumed that children turn their heads towards
sound sources they perceive as novel
✴Used as an index of detecting a change in stimuli
Head-Turn Preference
- how to test
Light in the center blinks to get fixation
- light goes out when child looks
light starts blinking either on left/right
- when the child looks at light, a sound is played
- sound stops when child looks away
or child looks at center and play new sounds to either side
- looking to new sound indicates detection of change
Normative Assessments
Standford-Binet intelligence scales
- ages 2 to 85+ years old
- measures verbal and nonverbal abilities
- normative scores, M= 100, SD= 15
Normative assessment
subscales:
- fluid reasoning
- knowledge
- working memory
- quantitative reasoning
- visuospatial processing
Normative assessment
Wisconsin card sorting task
- “Set-shifting”- rules for sorting change throughout
- diagnostic for children and older adults
- generally measures frontal lobe function
Neuroimaging
Structural measures
- magnetic resonance imaging (MRI)
- Diffusion tensor imaging (DTI)
neuroimaging
Functional measures
- Functional MRI (fMRI)
- Electroencephalogram (EEG)
- Event-related Potentials (ERPS)
- Magnetoencephalogram (MEG)
Magnetic Resonance Imaging (MRI)
- great spatial resolution (-1mm)
- great soft tissue contrast
- white vs. gray matter - no ionizing radiation (as in x-rays)
- measure depends on magnetic
properties of hydrogen
- MRI machine creates powerful
magnetic field (teslas)
Diffusion Tensor Imagining (DTI)
- utilizes same machine as MRI (different “scan”)
- measures diffusion of water within the brain
- used to image structure of white matter connectivity
- tractography: which regions are connected and by what fibers?
functional MRI (fMRI)
- same machine as MRI but different ‘scan’ during task
- measures changes in blood flow
- BOLD: blood oxygenation level dependent signal
- more oxygen used by areas that are active
- requires contrast between conditions (task of interest vs. resting baseline)
functional MRI (fMRI) advantages / disadvantages
advantages
- great spatial resolution (-3mm)
- noninvasive and relatively child-friendly
disadvantages
- poor temporal resolution (~6-10 seconds)
- disrupted by movement
- very expensive
- very loud
Electroencephalogram (EEG)
- raw EEG from electrodes in a cap placed on my head
1) put cap on head
2) put gel in buttons
3) place electrodes
Event-related brain potentials (ERPs)
- average on-going EEG by stimulus type
- time-locked to the onset of a specific stimulus
multiple measures:
- amplitude (How much)
- latency (when)
- scalp distribution (where)
Event-related brain potentials (ERPs)
advantages/ disadvantages
advantages:
- excellent temporal resolution (ms)
- noninvasive and very kid friendly
disadvantages:
- poor spatial resolution
- disrupted by motion and eye artifact
magnetoencephalogram (MEG)
advantages/ disadvantages
advantages:
- spatial resolution ~ MRI with temporal resolution of EEG
disadvantages
- cannot image subcortical areas
- very expensive
brief history of genetics
Father of modern Genetics
- Gregor Mendel (1822-1884)
- Austrian Monk
- Studied pea plants
examined
- flower color. position
- seed color, shape
- pod color, shape
- stem length
noticed that cross-breeds did not have intermediate stages of traits
Mendel’s Theory
- pea plants can self- or cross- pollinate
- cross-pollination of purebred parents followed by self-pollination for several generations
- first generation all had the same traits
- second generation had some of one trait and some of the other.. but no mixing
Mendel’s Theory
Dominant-recessive patterns
homozygous - same two alleles present
heterozygous- two different alleles
- if heterozygous, only one of the traits will be expressed (dominant)
- but heterozygous gene could combine with a recessive gene later to produce the recessive trait
Mendelian Patterns
- few human traits follow this simple pattern; most genes= multiple traits
- both alleles/blending can be expressed
- genes inherited from mother vs. father may be expressed differently
Deoxyribose Nucleic Acid
- genes: sets of chromosomes that are the basic unit of heredity in all living things
- carry the code for proteins
- regulatory genes control activity of other genes
- genes are continually turned on/off during life
Allelic variation
- variability in certain genes exist in the population
- 5 HTT: serotonin transporter gene
- long allele: greater serotonin transporter transcription
- short allele: less transcription- may be more susceptible to pathologies, yet may offer cognitive advantage
We are family
Genetic similarity with:
other humans: 99,9% chimps/bonobos: 98.8% orangutan: 96.9% rhesus monkey: 93.0% cats: 90.0% sea sponge: 70.0% bananas: 50.0% bacteria: 25.0%
genotype vs. phenotype
genotype: inherited genetic materials
phenotype- observable characteristics of the genotype
epigenetics
- genes are modified by experience
- modifications can be inherited by offspring
mechanisms of epigenetic signaling
- methylation can alter the expression of a given gene
- changes in methylation occur with experience and are heritable
- more nurturance increases ability to dampen HPA stress response
- —– removes methyl groups from gene linked to cortisol receptors
behavioural genetics
- we know that environment affects gene expression but we typically cant manipulate environment
- different environment can lead to different outcomes for individuals with the same genes
Dominant vs recessive phenotypes
Dominant
- curly hair
- full head of hair
- dark hair
- thick lips
- cheek dimples
- farsightedness
- type A or B blood
- Rh+ blood
Recessive
- straight hair
- pattern baldness
- blonde hair
- thin lips
- no dimples
- nearsightedness
- type O blood
- Rh- blood
genetic disorders
- recessive alleles
- albinism
- cystic fibrosis
- phenylketonuria (PKU)
- Tay-Sachs disease
- Sickle-cell disease
other genetic disorders
- huntington’s disease
- dominant allele on chromosome 4 - down syndrome
- extra 21st chromosome - hemophilia
- gene carried on the X chromosome
- more prevalent in males (XY)
- females (XX) can be buffered by dominant allele
prenatal development stages
- conception
- zygote
- embryo
- fetus
conception
occurs when egg and sperm meet in the fallopian tube
- each parent provides a gamete (egg/sperm)
- 23 chromosomes each = 46 total
- only 23rd chromosome differs by gender
largest human cell
smallest human cell
the egg is the largest
the sperm is the smallest
only __ sperm survive the __ hour voyage
200
~6 hour
nuclei of egg and sperm merge into a
zygote
zygote
- a fertilized egg cell (46 chromosomes)
- rapid cell division begins to take place
- zygote tuns into blastocyst (~100 cells)
- “Germinal stage” ends when implanted into uterine wall (~ 2 weeks)
embryo
embryonic stage
weeks 3-8
embryonic stage`
- cell division
- cell migration
- cell differentiation
- cell death
- hormones
• Cell division: from 1 to trillions of cells in 38 weeks
• Cell migration: movement of newly formed cells to destination
• Cell differentiation: specialization of cells for given function
• Cell death: genetically programmed death of some cells
• Hormones: sexual differentiation; fetus regulates own development.
Embryo`
embryo formed from
inner cell mass of zygote folding into 3 layers
neural tube
one end becomes brain, other end becomes spine
ectoderm/ mesoderm/ endoderm
- ectoderm: nervous system, inner ear, eye lens, outer layer of skin, nails, teeth
- mesoderm: muscles, bones, circulatory system, inner layers of skin, internal organs
- endoderm: digestive system, lungs, urinary tract, glands
amniotic sac
placenta
umbilical chord
- amniotic sac: fluid-filled membrane around embryo and later, the fetus
- placenta: semi-permeable organ that allows exchange of materials in mother’s blood to the fetus
- umbilical chord: connection of blood vessels between mother and fetus (to/from placenta)
fetal stage weeks
weeks 9-births
cephalocaudal development
areas closer to the head develop earlier than areas farther from the head
Fetus
sensory development
- touch/ taste/ smell/ hearing
- touch: feels its own body- face, fingers, umbilical cord
- taste: amniotic fluid flavor varies with mother’s diet
- smell: amniotic fluid smell varies with mother’s diet
- hearing: fetal environment is noisy
teratogens
external agents that damage prenatal environment
- damage dependent on critical period of exposure
- dose-response relationship
- Can be stress not just substances such as drugs and alcohol
maternal factors
- age: <15 & >35 years
- nutrition: low folic acids
- disease: rubella, STDs
- emotional state: perceived stress: fetal heart rate associated with mother’s self-reported distress
prenatal brain development
- first 4 weeks after conception
outermost layer of embryonic cells -> neural plate -> neural groove -> neural tube
neural tube development
- neural tube differentiates into 3 parts
- complete by 8 weeks
neural tube defects
ex. spina bifida
- ~1 in 1000 live births in US
symptoms
- leg paralysis
- orthopedic abnormalities
- reading disabilities
- difficulties with executive function skills
- other cognitive deficits
diet rich in folic acid linked to prevention of spina bifida
major development milestones
4-8 weeks: hemispheres of cerebral cortex emerge
8-26 weeks: cerebral cortex grows to cover midbrain
~28th week: cortical surface area expands, begins to fold
- most neurons you will have are now present
28-40 weeks: gyri and sulci of the brain begin to develop
neurogenesis
- formation of new neurons - almost complete by 18 weeks gestation
neural migration
- neurons move from innermost layers of tissue outward via glial cells
- cells formed earlier stay closer to their origination
- results in layers in the brain
neuronal migration defects
- misplaced or oddly formed neurons
- childhood epilepsy
- intellectual disabilities
- schizophrenia, dyslexia, and autism may be caused by mutations in genes that control neural migration
neural differentiation
- cell type is specific to a given area of the brain
- followed by synaptogenesis and dendritic branching
myelination
- insulates the axon- faster communication
- formed by glial cells- outnumber neurons 10:1
- begins in the 3rd trimester, continues through life
synaptogenesis
- formation of synapses between neurons
- huge growth from ~prenatal week 28 to ~2 years
synaptic pruning
- “use it or lose it”
- connections maintained are experience-based
- axons withdrawal and dendritic spine it synapsed on is pruned away
- neuroplasticity
frontal lobe
parietal lobe
temporal lobe
occipital lobe
frontal: executive function (planning, attention)
parietal lobe: spatial processing, information integration, somatosensation
occipital: vision
temporal lobe: audition, memory, emotion processing
postnatal brain development
- different neural components have different developmental trajectories
- gray matter decreases with age
- white matter increases into mid-adulthood then decreases- u- shaped curve
- cerebrospinal fluid (CSF) increases with age - different brain regions have different developmental trajectories
- regions for sensory functions mature early (visual and auditory cortex: limbic regions)
- regions for higher-order functions mature later - frontal lobe (executive function); posterior parietal - high degree of individual variability in development
- interaction of genes and experiences (neuroplasticity)
- brain uses input to fine-tune neural circuitry
pros:
- reduces the number of genes needed for development
- allows or better recovery from brain injury - younger brains generally heal better
cons:
- “double-edged sword” of neuroplasticity
- systems that re most susceptible to deficit with atypical experiences
- early cataracts- pruning of visual cortex
- language deprivation in feral children
Neuroplasticity and ASL
- participants
- task
participants
- native English speakers
- deaf native american sign language signers
- control group- hearing native ASL signers
task
- reading: English sentences vs. consonant strings
- viewing: ASL sentences vs. meaningless signs.
Sensitive periods
- timing of experience is key
- neural organization of different areas occur during specific periods in development
- lack of stimulation during that period can alter brain function and may be irreversible
examples:
- vision and hearing- very early in life
- phonology- within first year of life
- language- within first 5-7 years of life
experience-dependent plasticity
- neural connections created and reorganized throughout life based on individual experiences
- types of experiences you have shape your bran structure and function
ex. music, language, motor activities.
- types of experiences you have shape your bran structure and function
infant vision
- newborns prefer to look at stuff (than not stuff)
- habituation as an indicator of change detection
infants will likely spend less and less time looking at a repeated stimulus ..
but when the stimulus changes, looking time will increase if change was detected.
- less light strikes fovea
- 2% of all light (adults, 65%)
- 20/120 vision, or worse, in 1st month
less color experienced
1st month: shades of white
2-3 months: adult-like color perception
4-5months: adult like color preference
cones approach adult functionality at what age
8 months of age
visual acuity
- lens focus better by 3 months
- approaching adult levels by 8 months
- not fully adult-like until 6 years of age
visual scanning
- infants look around from birth
- tracking difficult because eye control and coordination are poor
- tracking becomes smoother by 2-3 months (if slow object)
- in 1st 2 months: only scanning one part or outer edges
- by 2 months - begin scanning entire object/ attention to overall shape and major details
Face perception
- from birth, infants show preference for human faces
- within 12 hours of exposure, an infant prefers image of mother
- can discriminate amongst facial expressions by 4 months
- by ~ 9 months, infants develop a prototype for faces they see
- – less able to discriminate between faces of other species, unless trained
- – 3 months old prefer female faces, unless father is primary caregiver
- – perceptual narrowing by experience
infant audition
sound processing
- hearing not adult-like until 5-8 years
- newborns tend to turn towards sound (as early as 10 min old)
- head-turn procedure
infant audition
- music processing
- infants pay more attention to consonant sounds than dissonance
- by 4.5 months, listen longer to melodies with pauses inserted in natural gaps (vs. unnatural gaps)
- by 5 months, recognize melody played at higher or lower pitch- remain habituated after familiarization
infants preference for taste
sweets
infants preference for smell
two-week olds prefer smell of their mom over a different woman
intermodal perception
- oral + visual
- tactile + visual
- audio + visual
oral + visual
- newborns and 1 month olds look longer at pacifier they had sucked on but hadn’t seen
tactile + visual
- 4-month-olds recognize rings they had explored with hands but hadn’t seen
audio + visual
- 4-month-olds prefer videos that match audio track
- 5-month-olds match facial expression to emotion
motor dev.- reflexes
grasping (palmar) tonic neck rooting sucking babinski, moro, blink, stepping, and withdrawal
disappearing reflexes
- stepping reflex usually disappears by 2 months old - unless given extra practice at this age
- leg fat grows faster than muscles do, until ~7 months
- – infants step more if supported by water buoyancy
- – younger infants step less if legs weighted down
Motor Milestones
- pre-reaching
- sitting & reaching
- crawling
- walking
cliff crawl
- infants will crawl over glass floors looking like a “cliff” until they have ~1 month experience with crawling
- when first crawling and waking, infants misjudge slopes that they are able to navigate safely - also influenced by social cues from caregiver
Mothers that experience more stress also show that
the fetus has an elevated heart rate as well
Can never go wrong with having too much
folic acids- the developing brain needs this fatty acid for developing brain cells and nerves that are lined with fatty layers
Neural tube development
- follic acid
- Clinical trials have shown that increasing your diet with folic acids can prevent spina bifida (prenatal vitamins)
forebrain becomes
CNS
You have more brain cells as a
fetus than you ever will as an adult
o The white matter is what develops and grows – newborn to 2 years
Glial cells
neuron travel along the glia to get where they want to get in the cortex.
Synaptic pruning
- Happens around 5 to 6 years of age
- When pruning happens you often maintain connections that have been solidating.
o Typically skills we have expertise - The brain is most flexible around age 4 (between 5-6 years)
o Train them around then so these skills are most likely to remain past the pruning event
Different areas of the brain mature at
different time points
A fully mature profile occurs around
26- the brain is still plastic and changeable though
- Sensory functions mature faster (visual and auditory)
o Don’t want to fully develop your ability to regulate and express higher order behaviours until you have experienced more things
o But visual and auditory are necessary
- Information goes in from your eyes to the back of your brain at the occipital lobe
o Using dorsal and ventral pathways information is sent throughout the rest of the brain
Information first goes to the temporal lobe where we go through our memories to see if we recognize what we are seeing
o Visual information will also travel upwards to the parietal lobe to tell us how things are moving
Spatial processing information
Sensations on your fingers and other parts of body that have spatial sensitivity light up in the front of the parietal lobe
o Cerebellum- balance – important
Eric Courchesne Autism Brain Growth video
- Understanding causes of autism
- Discovered a phenomenon; early brain overgrowth – brain in autism grows too large too fast at a very young age
o The brain gets too big – if they can figure out why the brain does this, they can help kids
o Looked at brain cells that grow in the frontal cortex (important for social communication – doesn’t work very well In beginning stages of autism)
o There is a 67% of over abundance of brain cells in the frontal cortex –
Probably means there is excess wiring- failure for this part of the brain to help the child learn communication skills
Need to change the course of the wiring patterns
When people are speaking in sign language there is a similar neuro pattern of activation
that can be seen in the brain when people are communicating to you verbally or through writing
- Late learners of ASL do not have right hemisphere activation
- Brains wiring for language really depends on your early experience
o Areas of the brain that represents language are plastic and malleable with experience
Over time there is a phenomenon called habituation – visual processes get
maxed out from seeing something for so long. (keeps seeing screen with black dashes) – if colour changes, they get reinterested
`cones process
rods process
- Cones are the cells in the middle of the eye – process colour
- Rods- process brightness 0 develop earlier
o Start with like black and white vision
Visual acuity
- Refers to how
sharp your vision is
- You want to put your face up real close to the enfant when talking to them so they have a chance at seeing your face and smile
Visual scanning
-infants dont have the higher brain function
to control their eyes like adults do
- In 1 month they can habituate between triangle and square
- Palmar reflex (grasping):
- Tonic neck:
- Rooting:
- Sucking:
- Babinski
- Moro reflex
- Palmar reflex (grasping): if you put something straight on an infant hand, they will grab onto it
- Tonic neck: place a baby down on their back and they will typically shift their weight and their arm will stick out in the direction they are looking
o Supports the neck - Rooting: stroke and infants’ cheek or put something near their mouth and they will think it’s a nipple and root towards it
- Sucking: natural reflex’s
- Babinski: stroke bottom of foot- toes span out
- Moro reflex: holding baby and you make their weight drop a little- their arms will reach out
Crawling motor milestone is usually there by
10 months
Walking milestone occurs
11-12 months
