Tuesday, February 14, 2012
382: Stress and Health: Your Heart
- Hypertension
- Terms
- Sympathetic tone
- Vasodilation
- Vasoconstriction
- Vagal tone
- The Cause
- Chronic stress leads to chronic elevations in blood pressure which leads to increased stress on blood vessels which respond by increasing cell wall muscles which decreases vessel diameter and makes vessel walls more rigid which leads to permanent hypertension.
- 90% of cases of hypertension are 'primary hypertension' which means that we don't know what is causing these cases
- 10% are 'secondary hypertension' which means secondary to physical disease process such as kidney disease
- Dr. Lancet Donnison 1929
- Discovered that blood pressure does not have to rise with age
- Hypertension is a function of a 'high pressure existence'
- This was the beginning of the understanding of stress and blood pressure
- Circulatory System
- Movement of blood to feed tissue and remove waste
- Left Ventricular Hypertrophy
- Inflammation
- Tends to happen at points of Bifurcation
- Hypertension contribues to cell wall damage
- Inflammation response is body's way to heal damage (cholesterol used in healing process)
- Atherosclerosis
- Disease characterized by the build up of fatty deposits in the arteries
- Can block blood flow
- Lack of blood flow can result in ischemia
- Macaque Video Clip
- It's not just diet that leads to this plaque buildup but also stress as seen in the social hierarchy of the macaques
- Ischemia
- Heart muscle is not fed by blood moving through it
- Cardiac ischemia
- lack of oxygen to heart muscle
- results from blocked coronary vessels
- Ambulatory studies: ischemia is very common
- Angina
- This is where someone has heart pain
- SNS/PNS Balance
- Optimal health requires the sns and pns to work together in a balanced way
- Chronic stress leads to increased sns activation and decreased pns activation
- PNS in heart health is currently a hot topic
- Voodoo Death
Monday, February 13, 2012
304: Validity
- Validity "the degree to which a test actually measures what it purports to measure"
- Gave an example of the GARS and how it is not a sensitive enough measure of autism yet is still used in most public schools in this area probably because it has good marketing
- Reliability
- Essential for validity but not all inclusive
- Face Validity
- Not a true measure of validity since a measure can look ok but not actually measure what it purports to measure
- Often it is important to have a low face validity so participant's answers can remain unaffected
- However, there are still instances where high face validity can be useful
- Why?
- It may increase the risk of measurement error
- It may also help motivate because the test appears relevant to the subject
- Content-Related Validity
- Definition
- The degree to which a test or measure adequately represents the conceptual domain (universe) it is designed to measure
- CVR
- Uses a panel of judges to rate items on a 3-point scale
- > 50% of judges consider it essential then it has validity
- Criterion-Related Validity
- Sub-types
- Predictive Validity
- The accuracy with which a test predicts a criterion obtained at a later time. SAT is the predictor and college GPA is the criterion
- Concurrent Validity
- At the same time. Give you a test now and I'll interview your supervisor and see how well those match up
- Postdictive Validity
- Score predicts a previously obtained criterion. I'll take a bunch of prisoners, give them a test, and I will be able to guess what kinds of crimes they committed in the past
- Validity coefficient
- Relationship between a test and a criterion
- Validity coefficient squared (interested in this rather than just the validity coefficient)
- The percentage of variation in the criterion we can expect to know in advance because of our knowledge of the test score
- Most of the time a low validity coefficient will mean the results are not worthwhile. What are some situation with a low validity but they still may be completely necessary and worth it?
- Concerns with interpreting validity coefficients
- Has the cause of relationships changed?
- What does the criterion mean?
- Nothing if it is not valid and reliable
- Was a representative subject population used in the validity study?
- The GARS was useful for the population studied but has low external validity to other populations
- Is the sample size adequate?
- Never confuse the criterion with the predictor
- Remember you want successful graduate students and not successful GRE scores
- Is there restricted range on both the predictor and the criterion?
- Review evidence for validity generalization
- Consider differential prediction
370: Perceiving Depth and Size: Monocular Cues
- One Eye vs Two Eyes
- We know some basic reasons why two eyes help the brain assume a 3D world but what if you only have one eye?
- You do lose some depth perception but not all of it
- Oculomotor Cues
- Oculomotor: cues based on sensing the position of the eyes and muscle tension. As you converge/diverge your eyes it indicates things are getting closer/further away.
- Accommodation: change in the shape of the lens when we focus on objects at different distances
- One can't diverge beyond parallel vision
- Lens
- Things that are closer the lens will be thicker
- Things further away the lens will be thinner
- Monocular Cues
- Monocular: cues that come from one eye
- Pictorial cues: sources of depth information that come from static 2D images
- Familiar size: this is a weak cue
- Atmospheric perspective: things get bluish as they get further away
- Texture grading: things closer have more detail and texture
- Shadows: can reveal height but necessarily distance from us
- Occlusion: occluded objects are further away
- Relative height: closer to the horizon = further away
- Relative size:
- Perspective convergence: parellel lines tend to converge in the distance
- Motion Cues: sources of depth info requiring...
- Objects closer than fixation point "move backward" relative to moving observer
- Objects further away will "move along" with the moving observer
- Motion Parallax
- one eye, moving from left to right, fixated at infinity showing how the images of a nearby tree and a faraway house move, the image of the tree will move more than the image of the house.
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