Week 3: Inferential Goals and Brainstem and Cerebellum Function Flashcards
What is scientific inference in psychology?
Scientific validation of ideas relies on making inferences based on available evidence
Data are not all created equal! - Differences in “quality”
Inference requires judging how strongly data support a claim
What are the requirements for making an inference?
Evaluating the quality of the evidence
Does the measure assess what the researcher says it assesses?
Is the evidence reliably reproducible?
Is the evidence measured quantitatively and objectively?
Evaluating how the evidence relates to theory
Is the evidence consistent with one theory or multiple theories?
Do any theories fail to explain the evidence?
What is a quantitative measurement?
Allows us to put a numerical value on a measurement
“Tall” is no longer subjective or relative
Permits objective measurement by others
Perhaps most importantly, quantitative measurement allows for comparison
Of groups of individuals
Of the same individual through time
What do we do with samples and populations and what are the potential pitfalls?
In most cases, we measure something about a sample of people and seek to form generalized conclusions about the population at large
What is true of the sample/population need not be true of the individual
What is true of the sample need not be true of another sample (even if both are drawn from the same population)
What two factors should measures contain for valid inferences?
Measures should be both reliable and valid
What is reliability?
Refers to how “repeatable” or consistent a measure is
If you were to assess the same construct in the same way using the same method of measurement, do you tend to get the same results?
What is Validity?
Refers to the degree to which a measure assesses the thing it is purported to assess
Is the construct you seek to measure actually related to the measurement?
What was the hot topic of the 19th century that was discussed?
Racial hierarchy, tried to use cranial capacity to determine that whites were smarter. Used mustard seeds but was not repeatable and then used buckshot.
What was the problem with the cranial capacity issue in terms of reliability and validity?
Problem: Cranial capacity does not really relate to intelligence… It’s not the size, it’s how you use it
But cranial capacity does relate to overall body size
Morton’s measure is conflated with body size (and potentially nutrition, etc.)
If the measure is not a valid reflection of the construct of interest, neither are the inferences based on the measure.
What are the three measures of central tendency?
Mean (average score)
Median (the “middle” score in a distribution)
Mode (the most common score)
What are the measures of variability?
Range Measures
Standard Deviation
What can occur between the use of different measures?
Quantitative measurement provides the basis for making defensible scientific inferences that are grounded in data
However, choosing an appropriate measure is not always straightforward—measures must be reliable and valid
Even with good measures though, there is a problem that is created by variability of data across different samples
How likely would a difference be between a treatment and control group of an unsuccessful drug?
A truly ineffective treatment would mean both groups score the same
So a large difference would be very unlikely if the treatment were ineffective
If we see a large difference, conclude the treatment is effective
What can alter the values of two sample groups?
Due to variability in samples though, the groups won’t have exactly the same mean score even if the treatment is ineffective
Usually small differences, sometimes positive, sometimes negative …but sometimes a very large difference will occur due to chance
Why are multiple studies needed?
False positives, cause the wrong effect to be accounted for.
What is the difference between practical significance and statistical significance?
Differences that are larger than would be expected by chance are considered to be “statistically significant”
This is a separate issue from “practical significance” (useful result).
What are some of the issues relating evidence to theory?
Issues when evaluating scientific claims based on statistical evidence
Can another theory explain the same data?
Are there theories that cannot explain the data?
If other theories can explain the same data, future work will need to try and distinguish between those theories!
If there are theories that are unable to explain the current data, they may need to be modified, or potentially abandoned
What is the brainstem/ANS associated with?
States of consciousness
What is the Cerebellum/Motor System associated with?
Feedback control of movement
What comprises the central nervous system (CNS)
Brain and spinal cord
What comprises the peripheral nervous system (PNS)
Somatic Nervous System
– Voluntary
– Motor and Sensory
Autonomic Nervous System
– Involuntary
– Heart-rate, respiration, sweating
– Stress, arousal, “fight-or-flight”
What are the two divisions of the ANS? (autonomic nervous system)
Sympathetic Nervous System – Emotional arousal, stress, fear – “Fight or Flight” response – Increases heart-rate, respiration, perspiration, pupils dilate.
Parasympathetic Nervous System – “Rest and digest” – Lowers heart-rate, respiration – Increases stomach, intestine activity (digestion) – “opposes” the sympathetic nervous system
What are some functions of the Brainstem
Autonomic nervous system functions
Relay between cortex and spinal cord cortex and cerebellum
What comprises the Brainstem?
Medulla oblongata, pons, and midbrain
What is the function of the Medulla?
Autonomic nervous system functions
Controls heart-rate, respiration, regulation of blood pressure, body temperature
Reflex centres for coughing, sneezing, swallowing, vomiting
What are the two discussed disorders of consciousness?
Persistent Vegetative State and “Locked-in” Syndrome
What occurs during a persistent vegetative state?
Severe damage to upper brain (hemispheres and cortex)
If brainstem is not damaged, autonomic nervous system functions can remain
sometimes normal respiration, control of heart rate, some face and eye movements remain
Patients have no conscious awareness
What occurs during a “Locked in syndrome” state? What causes this?
Amyotrophic Lateral Sclerosis (ALS) or Motor Neuron disease – Loss of motor neurons to spinal cord
or Brain injury (following accident)
Intact cerebrum and brainstem, but
“disconnected” from spinal cord
Normal cognitive function, vision, and
hearing, but patients cannot move
Patients may be fully conscious and
aware, but totally unresponsive
How can Persistent Vegetative State and “Locked-in” Syndrome be distinguished?
“Locked-in” patients appear the same as those with persistent vegetative state
Cortex is fully functioning in Locked-in patients
What is their conscious awareness?
Functional MRI to detect brain activity
and allow some communication
What are the functions of the Cerebellum
Hind brain (latin for little brain)
Sense of balance and co-ordination of complex movement
Motor learning – fine adjustment of movement based on feedback
What does primary motor cortex activity lead to?
Movement (muscle contraction), found anterior to central sulcus
Remember Homunculus distribution.
What does sensory cortex cortex activity lead to?
Leads to sensation, found posterior to central sulcus
Remember Homunculus distribution.
What are motor programs for movement?
Movements planned and “programmed” in the brain before initiation, like a computer program (theory from 1960’s)
Brain creates program just before movement.
OR
Brain retrieves program for learnt skilled actions – eg signature, tennis swing, etc
What is the feedback loop for a planned action?
Vision/Proprioception/sensation is compared to the desired and expected result, learning occurs
What are the three levels of the brain and their functions?
Going from Lower to higher
- Brainstem, Cerebellum Autonomic nervous system functions (heart-rate, respiration, blood pressure) Movement co-ordination (Low Level)
- Limbic System Fear/threat learning (amygdala) memory, navigation through environment (hippocampus) (Higher Level)
- Cerebral Hemispheres – Cortex Planning, reasoning, problem-solving (frontal lobe)
Language (temporal lobe)
Visual Perception and Action – perceiving complex world and interacting within it. (occipital and parietal lobe; motor cortex) (Highest Level)
What did the Stroop experiment show?
Reading seems to be an autonomic process which are hard to override.
