MEDIATION 1. History: S R explanations do not address full range of psychological phenomena. In many cases, S O R makes more sense. 2. Function:

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