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Memory and Belief Formation
Initial registration date
October 27, 2020
March 08, 2021 12:42 PM EST
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Other Primary Investigator(s)
University of Oxford
Additional Trial Information
We investigate the role of memory in how individuals form probabilistic beliefs. In particular, we present subjects with a series of images with multiple features (content vs color). We measure how beliefs about the distribution of these features vary depending on both normatively relevant and normatively irrelevant features of the distribution of images. We plan to connect these results to a model of memory to explain why sometimes people hold too extreme of beliefs, while at other times beliefs appear to be too conservative.
Intervention Start Date
Intervention End Date
Primary Outcomes (end points)
Our primary outcome variable is respondents' beliefs about the probability that a randomly drawn image has a certain content (word vs number) conditional on receiving information (or not) about whether the image is a certain color (blue vs orange).
[Added after first set of experiments]: In the second part of the experiments, our primary outcome variable is respondent's beliefs about the probability that a randomly drawn word belongs to a certain category.
Primary Outcomes (explanation)
Secondary Outcomes (end points)
We have several secondary outcomes. We measure how confident subjects are (on a likert scale) that their probabilistic answers are correct. We also have two separate memory tasks. First, respondents are given a series of four words, and are ask "Was X (in C) among the images you were shown?" where C is a color and the word X is displayed in that color font. The correct answer to this question is always "no", and we are measuring how frequently respondents incorrectly believe that they saw the word. Our second memory task simply asks them to list all the orange words they remember having been shown.
[Added after first set of experiments]: In the second part of the experiments, we also have certainty measurements, as well as recall measurements for each category.
Secondary Outcomes (explanation)
We present subjects with a series of images with multiple features (content vs color). We measure how beliefs about the distribution of these features vary depending on both normatively relevant and normatively irrelevant features of the dsitribution.
Experimental Design Details
We use qualtrics' randomization function.
Treatment is randomized at the individual level. The order of images, conditional on treatment, is randomized as well.
Was the treatment clustered?
Sample size: planned number of clusters
[Second wave of experiments]: Also 1200 individuals
Sample size: planned number of observations
Sample size (or number of clusters) by treatment arms
150 respondents per treatment group.
[Second wave of experiments]: 240 respondents per treatment group
Minimum detectable effect size for main outcomes (accounting for sample design and clustering)
This sample size is sufficient to detect a 7pp difference in mean posteriors between treatments with 80% power and significance level p < 0.05. The standard deviation of these outcomes (from pilot data) is about 20pp.
INSTITUTIONAL REVIEW BOARDS (IRBs)
Bocconi Research Ethics Committee
IRB Approval Date
IRB Approval Number