**Manipulation Check**
We ran an ANOVA on how difficult participants found it to list things about themselves that had changed with easy/difficult as one factor and highschool/4-8 years as the second factor. This was done with the following code:
BOOTSTRAP
/SAMPLING METHOD=SIMPLE
/VARIABLES TARGET=manipcheck INPUT=hs difficult
/CRITERIA CILEVEL=95 CITYPE=PERCENTILE NSAMPLES=10000
/MISSING USERMISSING=EXCLUDE.
UNIANOVA manipcheck BY hs difficult
/METHOD=SSTYPE(3)
/INTERCEPT=INCLUDE
/EMMEANS=TABLES(OVERALL)
/EMMEANS=TABLES(hs) COMPARE ADJ(LSD)
/EMMEANS=TABLES(difficult) COMPARE ADJ(LSD)
/EMMEANS=TABLES(hs*difficult)
/PRINT=DESCRIPTIVE
/CRITERIA=ALPHA(.05)
/DESIGN=hs difficult hs*difficult.
We found that the manipulation was successful at increasing difficulty of memory, participants in the recall 12 items found it more difficult to do so M = 3.652, SD = 1.843) than 3 items (M = 2.538, SD = 1.808; *F* (1, 1496) = 140.79, *p* < .001). This effect was also magnified in the high school group (*F* (1, 1496) = 4.034, *p* < .045) most likely because high school was further in the past for participants in this sample than the original study which used college students.
As we replicated the manipulation check in both high school and 4-8 years ago conditions, we pursued follow-up testing on the primary dependent variable of observing change.
Primary Dependent Measures
Given that the manipulation worked, we combined the four dependent variables into a summary score, consistent with the original study.
We then ran separate-variance t-tests on both the high school and the 4-8 years ago samples.
We found no evidence that making it appear that more or less change has occurred (using the easy vs. hard recall manipulation) led to changes in the beliefs that the world has changed (both *p*s > .45).
In the high school sample, participants who were randomly assigned to try and recall 12 ways they had change thought the world had changed just as much (M = 13.598, SD = 5.46) than if they had been asked to recall 3 ways they had changed (M = 13.755, SD = 5.107, *t*(732.883) = .405, *p* = .685).
In the 4-8 years ago sample, participants who were randomly assigned to try and recall 12 ways they had change thought the world had changed just as much (M = 16.69, SD = 4.463) than if they had been asked to recall 3 ways they had changed (M = 16.932, SD = 4.35, *t*(745.782) = .752, *p* = .452).
