Moderators and Mediators

Moderators and Mediators Class 9

Class Business Class Business Class Business 1. Quiz 1: Returned end of class 2. Midterm: Rescheduled to Oct. 22.

Breaking News: Mud Improves Memory!!! FLASH! Explorers in the Amazon have discovered an amazing “memory mud”. When smeared on the forehead it vastly improves short term memory. However, it appears that “mem-mud” works only for certain kinds of people in certain places at certain times. The mud appears to have its powerful effects because ……[SIGNAL LOST]. What questions arise? Who does it work for? Under what conditions? At what times? Moderators Mediators Why does it work?

Moderators, Mediators, and Mem-mud Moderator:What are the conditions under which Mem-mud works, and for whom does it work? Mediator:Why does Mem-mud work Moderator: The limiting conditions that determine an effect or an outcome (e.g., when, with what, or for whom). Mediator: The underlying cause; Why something occurs.

MODERATOR DEFINED A moderator is a variable that affects the direction or strength of the relationship between a predictor (IV) and an outcome (DV). A  B, if C is a moderator model. A = Predictor = B = Outcome = C = Moderator = Changes in the moderator will affect the relation between IV and DV. Moderators directly explain how and when events occur (but can also indirectly indicate why they occur). Moderator can be: * qualitative variable (race, sex, etc.) * quantitative variable (perceived risk, mood, temperature) Memory Mud Memory Temperature

MODERATOR DEFINED, Cont. Moderator is always an Independent Variable Moderators sought when there is weak or inconsistent relationship between IV and DV. Moderator confirmed only if interaction between moderator and main IV is significant F [mud * Temp] = 8.54, p < .05. Moderator should be un-correlated to DV ST M STM = Short Term Memory LTM = Long Term Memory

Problem when Moderator Correlates to DV Amount of Domestic Violence Amount of Drinking Amount of drinking and being an alcoholic are highly correlated r = .70, p < .001. Why is this a problem? Is the entire story simply about proximity to liquor store?

Uncontrollable Bad Event (World Economy Fails) Controllable Bad Event (Made Bad Investment) Major Event and illness r = .56 * Major Event and illness r = .12 Moderation: Correlation Between IV and DV is High in One Condition But Not in Another. These two results say what about bad events and illness? Major life events  increased illness, IF event is uncontrollable. Moderator is? CONTROLLABILITY

Perceived Distance to Scary Object How close is the object? Distance Dependent Variable? Perceived Distance Primary Independent Variable? Object Type (scary / neutral) Self-Worth (high / low) Moderator? NOTE: Moderator is ALWAYS IV. Identifications of Primary IV and Moderator are arbitrary

MODERATOR MODEL Predictor (IV) Moderator (IV) Outcome Variable (DV) Predictor X Moderator P X M Interaction Must be significant Object scariness(IV) Self-worth (IV) Distance Perception (DV) Scariness X Self-worth p < .05

Positive Feedback Bias With and Without Content/Mechanics as Moderator Feedback Positivity Feedback Positivity Shows how moderation can be explored when there is weak relation between IV and DV

Moderator “Recipes” a. IV is qualitative (dichotomous, polychotomous, Mod. is qualitatitve (dichotomous, polychotomous) b. IV is qualitative, Mod. is quantitative c. IV is quantitative, Mod. is qualitative d. IV is quantitative, Mod. is quantitative

Social Contact, Disclosure, and Ratings of Baby Cries Primary IV? Social Contact Moderator Disclosure DV? Distress Rating Recipe? IV is Qualitative, and Moderator is Qualitative

Height Perception as Function of Social ContactAdapted from Schnall, Harber, Stefanucci, & Proffitt, 2008Results amplified for purposes of illustration “How long have you known Person?” Primary IV? Social Contact Moderator Duration DV? Hill slant Recipe? IV is Qualitative, and Moderator is Quantitative

Primary IV? Depression Moderator Gender DV? Endorsement of Directive Support Recipe? IV is Quantitative, and Moderator is Qualitative

Self Esteem and the Use of Affect as Information (Harber, 2005) Mild upset = 1 SD < mean, Moderate upset = mean, Extreme upset = 1 SD > mean. Primary IV? Upset Moderator Esteem DV? Baby Cry Ratings Recipe? IV is Quantitative and Moderator is Quantitative

Moderators Indirectly Indicate Underlying Causes Children are aggressive mainly when: a. Teachers do not pay attention to them b. Their parents are rarely at home c. They have few friends Underlying cause? Lack of belonging, Isolation People show low empathy when: a. They have many deadlines b. They have mounting bills c. They have many work demands Underlying cause? Stress

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: Mediational analyses designed to test for SOR 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. What we see. What rat sees.

Mediational Model Mediator a b DV IV c When Mediation is present: r (a) is significant r (b) is significant r ( c ), which was significant before the mediator was considered, is either not significant or is much weaker after accounting for mediator (i.e., subtracting mediator effect from a  c effect). NOTE: r = correlation coefficient

Attributes of Mediators Mediator 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 DV Immuno- compromise Latent variable: Lower T Cell, Lower immunoglobulin, higher cortisol. Stress Illness

Self-Image Concerns a b c Race of Recipient Positive Bias Mediational Model and Feedback Studies IV? Race of recipient DV? Positive bias Self-image concerns Mediator? No. "b" must also be sig, AND... "a" is significant. Mediation shown? When "a" and "b" considered, "c" no longer significant. What shows mediation here?

Why Do People Need Self Esteem? Converging Evidence that Self Esteem Provides an Anxiety-Buffering Function Greenberg, et al., 2000 It was hypothesized that raising self-esteem would reduce anxiety in response to vivid images of death. In support of this hypothesis, subjects viewed either a neutral movie or a disturbing movie, and had their self-worth boosted or unchanged. As predicted, scary movies led to greater anxiety but not among boosted self-worth subjects. X ____Moderator ____Mediator

Greenberg, et al. 2000 Scary Images + Self Esteem 0 Anxiety +++ Scary Images X Self Esteem

Anxiety as a Function of Threat Salience and Level of Self Esteem Greenberg, et al., 2000

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 ] X ____Moderator ____Mediator

Katkin, Wiens, & Öhman, 2001 Heartbeat Monitors a b c Stimuli Sensitivity Conditioned Fear

Mediators Indirectly Suggest Moderation (Limiting Conditions) Isolation leads to conformity because of need to belong. How is conformity affected by: Age? Transfer student or long-term resident? Experienced ostracism? Frustration leads to hostility because of elevated heart rate. How is hostility affected by: Amount of coffee consumed? Daily stress? Beta blockers? Having a “high reactivity” personality?

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 --> [????] --> coping Disclosure --> self-affirmation --> coping (Cresswell, et al., 2007) Disclosure --> self-affirmation --> [????] --> coping

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. 21st Century is expected to reduce Stereotype threat, leading to improved grades. • Stereotype threat is itself a problem because it causes minority students to dis-identify 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 ID with School Stereo. Threat 21st Cent. Prog. Grades 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

Moderators and Mediators