Moses, money, and multiple-choice: The Moses illusion in a multiple-choice format with high incentives.

When people answer the question "How many animals of each kind did Moses take on the Ark?", they usually respond with "two," although Moses does not appear in the biblical story of the Ark. We investigated this "Moses illusion" in a multiple-choice format and tested the influence of monetary incentives on the illusion's strength. Thereby, we addressed the role of a cooperative communication context for the illusion's emergence, as well as the role of participants' motivation. In four experiments (total N = 914), we found that the Moses illusion persists in a multiple-choice format. As the multiple-choice format realizes a cooperative context in which the correct answer is always available, we exclude a cooperative context explanation for the illusion. Monetary incentives reduced the strength of the illusion. However, the reduction was numerically and statistically small. We thereby show that the illusion is not due to violations of cooperative communications, and not due to a lack of motivation. The multiple-choice approach will facilitate further research on the Moses illusion and the data provide additional evidence for the Moses illusion's empirical robustness and constrain its theoretical explanations.