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
