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MEDIATION
1. History: S R explanations do not address full range of psychological phenomena. In many cases, SOR makes more sense. 2. Function: Mediational analyses designed to test for SOR causal paths. 3. Mediation Defined: “the effects of stimuli on behavior are mediated by various transformations internal to the organism.” 4. Utility: Mediators directly explain why events occur (but can also provide clues to how and when they occur). 5. Character: Mediators are latent variables, or latent constructs.
Attributes of Mediators
1. IV predicts DV
2. Changes in IV account for changes in mediator 3. Changes in mediator account for changes in DV. 4. When links between IV to Mediator, and between Mediator to DV are established, the link between IV and DV becomes non-significant, or becomes significantly decreased
IV
Mediator
DV
Stress
Immuno-compromise
Illness
Mediational Model
IV
Mediator
DV
a b
c
When Mediation is present:
r (a) is significantr (b) is significantr ( c ), which was significant before the mediator was included, is either not significant or is much weaker after mediator is included.
Mediational Model and Feedback Studies
Race of Recipient
Self-Image Concerns
Positive Bias
a b
c
IV?
DV?
Mediator?
"a" is significant. Mediation shown?
What shows mediation here?
Race of recipient
Positive bias
Self-image concerns
No. "b" must also be sig, AND...
When "a" and "b" considered, "c" no longer significant.
Moderator to mediator: Knowing how external variables affect outcomes can imply the existence of mediators. Mediator to Moderator: Knowing why underlying mechanism affects outcomes can suggest ways of addressing, remedying, altering the outcome.
RELATION BETWEEN MODERATORS AND MEDIATORS
Scary Movie
Fitness
Movie X Fitness
Fear
Pos. Mediator: Physio. reactivity
Scary Movie
Scary Movie
Physio. reactivity
Fear
Pos. Moder:ator: Fitness
Why Do People Need Self Esteem? Converging Evidence that Self Esteem Provides an
Anxiety-Buffering Function
Greenberg, et al., 2000
Three studies assessed the proposition that self-esteem serves an anxiety-buffering function. In Study 1, it was hypothesized that raising self-esteem would reduce anxiety in response to vivid images of death or neutral images. In support of this hypothesis, subjects who received positive personality feedback reported less anxiety in response to a video about death than did neutral feedback subjects.
____Moderator ____MediatorX
Greenberg, et al. 2000
Scary Images
Self Esteem
Scary Images X Self Esteem
Anxiety
+
0
+++
Anxiety as a Function of Threat Salience and Level of Self Esteem
Greenberg, et al., 2000
0
10
20
30
40
50
60
Neutral Video Death Video
Anx
iety
Neutral Esteem
Positive Esteem
Visceral Perception and Nonconscious Fear Conditioning
Katkin, Wiens, & Öhman, 2001
Previous research shows that people conditioned to fear certain kinds of stimuli such as snakes or spiders are subsequently better able to detect hidden images of these stimuli compared to people who are not conditioned. The current research predicts that this heightened sensitivity is restricted to people who are good at detecting their own heartbeats (good heartbeat monitors). This prediction was confirmed; when good heartbeat monitors are excluded from analysis the effect of fear conditioning on stimuli sensitivity disappears. [ABSTRACT MODIFIED ]
____Moderator ____MediatorX
Conditioned Fear
Heartbeat Monitors
Stimuli Sensitivity
a b
c
Katkin, Wiens, & Öhman, 2001
Path Analyses and Causal Models
Attend. in 21st Century program improved performance by minority students.
21st Century program based on theory of stereotype-threat. When threat is high, minority students do less well.
Stereotype threat is itself a problem because it causes minority students to disidentify with academics.
What is the causal model? What would be strong and weak correlational links in this model?
First Semester Grades as Predicted by Stereotype Threat, Identification with School, and Participation in 21st Century Program
Stereo. Threat
Grades
ID with School
21st Cent. Prog.
Task: What are IVs, DVs?
What are moderators (if any)?
What mediators (if any)?
Put these in correct path
Estimate relations between variables, outcome
21st Century Program, Stereotype Threat, and Identification with School
Ultimate Mediation? The Epistemological Challenge of Science
Multiple underlying causes: Disclosure --> Emotional resolution --> less stress --> immune boost --> health Race of recipient --> egalitarian concerns --> self-image concerns --> bias Ultimate underlying causes: Disclosure ---> coping (Pennebaker, 1989)Disclosure --> [????] --> copingDisclosure --> self-affirmation --> coping (Cresswell, et al., 2007)Disclosure --> self-affirmation --> [????] --> coping
Independent Variables
Class 08
IV: Conceptual vs. Experimental
Conceptual IV: General class of causes relevant to underlying theory.
Examples: “Insult”, “Fear”, “Perceived Control”
Experimental IV: Specific operations used to represent the conceptual IV. Examples: “Bumped and sworn at by confed”, handling a live
snake, given “stop button” to stop stressful event.
Independent Variable: Conceptual and Empirical Forms
Conceptual IV Empirical Realization
Poorly executed performance Poorly written essay
Authority commanding obedience Experimenter saying “give shocks”
Demeaning clothes, ankle chains, numbers rather than names.
Prisoner experience
Fate of Ghakistani boyEthical dilemma
Race of essay writer Writer’s Description Sheet
Experimental IV, continuedExperimental IV typically of no theoretical value
However, Expt’l IV can be of great PRACTICAL value.
1. “Stop button” on pain manipulation affects pain tolerance: Practical Value?
2. Writing thoughts and feelings reduces hostility: Practical Value?
Subset of IVs that can be of both conceptual and experimental:
1. Demographics: Gender, race, nationality
2. Personality: Attachment style, self-esteem, etc.
Experimental IV May Change,
Conceptual IV is Constant
Insult, 1715: Your mother shops without a handmaid!
Insult, 1815: Your mother is a free thinker!
Insult, 1915: Your mother wears army boots!
Insult, 2015: Your mother is a junk-bonds trader!
Goals in Designing IV
Select IV that represents conceptual IV
1. Good IV is a good metaphor (Hurry to talk on Good Samaritanbefore encountering stranger in need.)
2. But, may also have direct practical value (Consider own virtuesbefore dealing with threat)
Present IV in a way that maximizes effect
1. For subjectsa. To induce interest (e.g. “you will receive shocks.”)b. To keep true purpose of study hidden from Ss
2. For outside audience: Want to tell good story
(“holding spouses hand, experimenter’s hand… “)
Instructions Form of IV
Written, verbal info. that conveys the IV Advantage:
1. High control 2. Work with populations un-suited for event manipulations3. Convenience, ease of use, economical
Success depends upon:1. Commanding Attention2. Comprehension of instructions
a. Keep design simpleb. Keep language simple
Prospect Theory: Kahneman & Tversky, 1984Demonstration of "Instructions" IV)
Newark is preparing for the outbreak of an unusual air-borne disease, which is expected to kill 600 people. Two alternative programs are available to combat the disease, but they cannot be used simultaneously. Which do you choose?
Loss Condition
Gain Condition
If Program A is adopted, 400 people will die.
If Program A is adopted, 200 people will live.
If Program B is adopted, there is a one-third probability that nobody will die and a two-thirds probability that 600 people will die.
If Program B is adopted, there is a one-third probability that 600 people will be saved, and a two-thirds probability that no people will be saved.
I pick: ____ Program A ____ Program B
Prospect Theory: Kahneman & Tversky, 1984Demonstration of "Instructions" IV)
Newark is preparing for the outbreak of an unusual air-borne disease, which is expected to kill 600 people. Two alternative programs are available to combat the disease, but they cannot be used simultaneously. Which do you choose?
Loss Condition
Gain Condition
If Program A is adopted, 400 people will die.
If Program A is adopted, 200 people will live.
If Program B is adopted, there is a one-third probability that nobody will die and a two-thirds probability that 600 people will die.
If Program B is adopted, there is a one-third probability that 600 people will be saved, and a two-thirds probability that no people will be saved.
I pick: ____ Program A ____ Program B
Vignette as Within-Subjects Manipulation
Adapted from Adler-Russell, 1983
Situation 1: Officer Clements is a third year patrol officer. HE/SHE responded to a domestic violence report, found husband threatening his wife due to over-draft. Officer Clements first confirmed that the wife was not injured nor feared injury, and informed her of protections and rights. Officer Clements then told husband, in front of wife, that further threats may lead to arrest.
How effectively did Clements respond to this situation?
Situation 2: Officer Williams is a third years patrol officer. HE/SHE responded to an armed robbery at a local convenience store. HE/SHE saw suspect waving a pistol at the clerk, while backing out of store. Officer Williams waited until suspect cleared the doorway and the clerk was out of danger. However, this provided suspect an opportunity to flee, and suspect is still at large.
How effectively did Clements respond to this situation?
Problems with Instructions Forms of IV
1. Lack external validity (e.g., Kahneman & Tversky)
2. Too abstracted (Joshua Greene moral choices)
3. Enlists subjects from the neck up
Event Form of IV Event: Actual situation that conveys the conceptual IV Advantages 1. Absorbing
2. Can approximate real world IV3. Tell a more compelling story
Problems 1. Not clear it exclusively conveys IV
2. Not easy to standardize3. Not economical, difficult to run
Common Forms of Event IV
1. Accident, unplanned occurrence
a. Smoke from vent
b. Person collapses in next room
2. Confederate
a. Culture of Honor (Cohen & Nisbett)
3. Whole experiment as manipulation (ethical problems here)
a. “Failed” egalitarian, then meet panhandler (Dutton & Lake)
4. Experiment w/n experiment
a . Self affirmation and lab coat (Steele)
5. Real world events:
War of Worlds, Y2K, Gulf War I, Movies, etc.
Standardization: Procedural and Psychological
Stimulus Event
This is event we can standardize
Stimulus Perception
This is event we ultimately want to standardize, but can’t directly control
Response
This is event intended to reflect only intended stimulus, and not any unintended stimulus.
Standardization: Procedural and Psychological
Stimulus Event
Stimulus Perception
Response
Standardization of IV
Goal: All subjects experience the IV in the same way. Procedural standardization: Standardize IV as given by E Flexibility in IV presentation: Standardize IV as experienced by S
Problems with flexibility?
Eine kleine “knock-knock” music
Pilot Testing of IV
Purpose: ID problems before experiment begins
1. Power of manipulation
2. Clarity: Alternative interpretations?
3. Presentation a. Believable? b. Production value?
4. Artifacts: Expt'l IV introduces unintended stimuli
5. Ways to bolster IV
Methods of Piloting
1. Interview subjects
a. Subs are great info sourceb. Highly motivated to helpc. Probe after IV, NOT at end of study (WHY?)d. Problems with interviewing?
2. Test against objective criterion a. Stress IV – bio measuresb. Use experts: Feedback task, professional tutors
Pilot Testing Using Objective Criteria
Prediction: Distress will lead urbanites, but not rural folk, to disclose personal feelings.
Conceptual IV: Distress
Empirical Realization of IV: Disturbing movie (e.g., Titanic sinks)
Pilot Test Goal: Is movie upsetting?
Post-Expt. Interviews: Limited value; if prediction is true, rural folk might not provide reliable info.
Objective Criteria: Non-verbal reactions (HR, GSR)
Internal Analysis
Purpose: To find out why experiment didn't work Tools:
a. Manipulation Checksb. Post hoc data analyses
Limits to conclusions from internal analyses Internal analyses valuable even when experiments "work"
Subliminal Priming: Special Class of IV
Purpose: Short cut to psyche; direct path into black box
* Get past conscious editor* Activate otherwise inaccessible mental processes
Nature: Exist between “instruction” and “event” manipulations. Examples:
* “Mommy and I are one”: Silverstein lower psych. symptoms Improve learning
* Happy/sad faces: Winkielman Ratings of Kool-aid Consumption of Kool-aid