Experimental Design Details
Respondents are shown 40 images. Each image is either a word or a number, and appears in either blue or orange font. Our primary outcome of interest is respondents answer to the following question: "Suppose the computer randomly chose an image from the images you just saw. It is orange. What is the percent chance that it is a word?" We have eight total treatments, which differ only in the distribution of words, numbers, and colors. We will certainly run the first six treatments, but we may decide against running the final two if maximum possible sample sizes at the lab are smaller than we hope.
Treatment 1: 10 orange words, 10 orange numbers, 0 blue words, 20 blue numbers.
Treatment 2: 10 orange words, 10 orange numbers, 10 blue words, 10 blue numbers.
Treatment 3: 10 orange words, 10 orange numbers, 20 blue words, 0 blue numbers.
Treatment 4: 14 orange words, 6 orange numbers, 0 blue words, 20 blue numbers.
Treatment 5: 14 orange words, 6 orange numbers, 6 blue words, 14 blue numbers.
Treatment 6: 14 orange words, 6 orange numbers, 20 blue words, 0 blue numbers.
Treatment 7: 11 orange words, 9 orange numbers, 20 blue words, 0 blue numbers.
Treatment 8: 9 orange words, 11 orange numbers, 0 blue words, 20 blue numbers.
Our theory predicts both a bias towards 50-50 and that, when there are more blue words, subjects will believe that a randomly chosen orange image is less likely to be a word, and vice versa. We first ask the probability of being a world conditional on the randomly chosen image being orange, then conditional on it being blue, then supposing they do not know it's color. Our primary outcome is the first question, and the other two are secondary. After each of these questions, respondents are asked how certain they are of their answers.
After this, respondents answer the memory questions described above.
[Added after first set of experiments]:
Respondents are shown 40 words. Each word will belong to a certain category, which will be described below (except for the random treatment). Our primary outcome of interest is respondents answer to the following question: "Suppose the computer randomly chose a word. What is the percent chance that it is a [Category]?" We have 5 total treatments, which differ in either the distribution of the categories, or the way the above question is asked, which can vary between asking about two categories (e.g. [Animals vs Others]) or three categories (e.g. [Animals, Men's names, and Women's names].
Treatment 1: 16 Land Animals, 12 Men's names, 12 Women's names, ask P(Animals vs Other)
Treatment 2: 8 Land Animals, 16 Men's names, 16 Women's names, ask P(Animals vs Other)
Treatment 3: 16 Land Animals, 12 Men's names, 12 Women's names, ask P(Animals) vs P(Men's name) vs P(Women's name)
Treatment 4: 16 Land Animals, 12 Men's names, 12 Sea Animals, ask P(Land Animals vs Other)
Treatment 5: 16 Land Animals, 24 Random Words, ask P(Land Animals vs Other)
Our primary outcome of interest is P(Land Animals), the primary category being asked. Our theory motivates the role of two forces: the way the question is asked (in terms of the precise hypothesis being cued: Treatment 1 vs 3), as well as the similarity across the elements within and across categories (Treatments 1, 4, 5: We predict Treatment 5 to be the biggest, while treatments 1&4 are ambiguous). Also, our theory implies a dampening of sensitivity to true probabilities (Treatment 1 vs 2). Furthermore, our theory in general predicts a link between recall (the number of words recalled for each category) and the probabilistic beliefs, as well as the fact that in recall, the presence of similar (but irrelevant) elements inhibits the recall of the category at hand, impacting probability beliefs.